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Brightly WH, Crifò C, Gallaher TJ, Hermans R, Lavin S, Lowe AJ, Smythies CA, Stiles E, Wilson Deibel P, Strömberg CAE. Palms of the past: can morphometric phytolith analysis inform deep time evolution and palaeoecology of Arecaceae? ANNALS OF BOTANY 2024; 134:263-282. [PMID: 38687211 PMCID: PMC11232524 DOI: 10.1093/aob/mcae068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 04/29/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND AND AIMS Palm fossils are often used as evidence for warm and wet palaeoenvironments, reflecting the affinities of most modern palms. However, several extant palm lineages tolerate cool and/or arid climates, making a clear understanding of the taxonomic composition of ancient palm communities important for reliable palaeoenvironmental inference. However, taxonomically identifiable palm fossils are rare and often confined to specific facies. Although the resolution of taxonomic information they provide remains unclear, phytoliths (microscopic silica bodies) provide a possible solution because of their high preservation potential under conditions where other plant fossils are scarce. We thus evaluate the taxonomic and palaeoenvironmental utility of palm phytoliths. METHODS We quantified phytolith morphology of 97 modern palm and other monocot species. Using this dataset, we tested the ability of five common discriminant methods to identify nine major palm clades. We then compiled a dataset of species' climate preferences and tested if they were correlated with phytolith morphology using a phylogenetic comparative approach. Finally, we reconstructed palm communities and palaeoenvironmental conditions at six fossil sites. KEY RESULTS Best-performing models correctly identified phytoliths to their clade of origin only 59 % of the time. Although palms were generally distinguished from non-palms, few palm clades were highly distinct, and phytolith morphology was weakly correlated with species' environmental preferences. Reconstructions at all fossil sites suggested that palm communities were dominated by Trachycarpeae and Areceae, with warm, equable climates and high, potentially seasonal rainfall. However, fossil site reconstructions had high uncertainty and often conflicted with other climate proxies. CONCLUSIONS While phytolith morphology provides some distinction among palm clades, caution is warranted. Unlike prior spatially restricted studies, our geographically and phylogenetically broad study indicates phytolith morphology may not reliably differentiate most palm taxa in deep time. Nevertheless, it reveals distinct clades, including some likely to be palaeoenvironmentally informative.
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Affiliation(s)
- W H Brightly
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
- Department of Plant and Animal Sciences, University of Sheffield, SheffieldS10 2TN, UK
| | - C Crifò
- Conservatoire d'espaces naturels de Provence-Alpes Côte d' Azur - Maison de la Crau, 13310 Saint-Martin de Crau, France
| | - T J Gallaher
- Bernice Pauahi Bishop Museum, Honolulu, HI 96817, USA
| | - R Hermans
- Archaeology, Environmental Changes and Geo-Chemistry (AMGC), Vrije Universiteit Brussel, Brussels 1050, Belgium
| | - S Lavin
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY 11794, USA
| | - A J Lowe
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - C A Smythies
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - E Stiles
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - P Wilson Deibel
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - C A E Strömberg
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
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Lloyd BA, Barclay RS, Dunn RE, Currano ED, Mohamaad AI, Skersies K, Punyasena SW. CuticleTrace: A toolkit for capturing cell outlines from leaf cuticle with implications for paleoecology and paleoclimatology. APPLICATIONS IN PLANT SCIENCES 2024; 12:e11566. [PMID: 38369978 PMCID: PMC10873815 DOI: 10.1002/aps3.11566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/25/2023] [Accepted: 11/01/2023] [Indexed: 02/20/2024]
Abstract
Premise Leaf epidermal cell morphology is closely tied to the evolutionary history of plants and their growth environments and is therefore of interest to many plant biologists. However, cell measurement can be time consuming and restrictive with current methods. CuticleTrace is a suite of Fiji and R-based functions that streamlines and automates the segmentation and measurement of epidermal pavement cells across a wide range of cell morphologies and image qualities. Methods and Results We evaluated CuticleTrace-generated measurements against those from alternate automated methods and expert and undergraduate hand tracings across a taxonomically diverse 50-image data set of variable image qualities. We observed ~93% statistical agreement between CuticleTrace and expert hand-traced measurements, outperforming alternate methods. Conclusions CuticleTrace is a broadly applicable, modular, and customizable tool that integrates data visualization and cell shape measurement with image segmentation, lowering the barrier to high-throughput studies of epidermal morphology by vastly decreasing the labor investment required to generate high-quality cell shape data sets.
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Affiliation(s)
- Benjamin A. Lloyd
- Department of Earth and Space SciencesUniversity of WashingtonJohnson Hall Rm‐070, Box 351310, 4000 15th Ave. NESeattleWashington98195‐1310USA
- Smithsonian Environmental Research CenterSmithsonian Institution647 Contees Wharf Rd.EdgewaterMaryland21037‐0028USA
| | - Richard S. Barclay
- Department of Paleobiology, National Museum of Natural HistorySmithsonian Institution1000 Madison Dr. NWWashingtonD.C.20560USA
| | - Regan E. Dunn
- La Brea Tar Pits and MuseumNatural History Museums of Los Angeles County5801 S. Wilshire Blvd.Los AngelesCalifornia90036USA
- Department of Earth SciencesUniversity of Southern California3551 Trousdale ParkwayLos AngelesCalifornia90089USA
| | - Ellen D. Currano
- Department of BotanyUniversity of Wyoming1000 E. University Ave.LaramieWyoming82071USA
| | - Ayuni I. Mohamaad
- Department of BotanyUniversity of Wyoming1000 E. University Ave.LaramieWyoming82071USA
- Department of Geological SciencesUniversity of Florida241 Williamson Hall, P.O. Box 112120GainesvilleFlorida32611‐2120USA
| | - Kymbre Skersies
- Department of BotanyUniversity of Wyoming1000 E. University Ave.LaramieWyoming82071USA
| | - Surangi W. Punyasena
- Department of Plant BiologyUniversity of Illinois Urbana‐Champaign139 Morrill Hall, 505 South Goodwin Ave.UrbanaIllinois61801USA
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Guo WY, Serra-Diaz JM, Eiserhardt WL, Maitner BS, Merow C, Violle C, Pound MJ, Sun M, Slik F, Blach-Overgaard A, Enquist BJ, Svenning JC. Climate change and land use threaten global hotspots of phylogenetic endemism for trees. Nat Commun 2023; 14:6950. [PMID: 37907453 PMCID: PMC10618213 DOI: 10.1038/s41467-023-42671-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 10/18/2023] [Indexed: 11/02/2023] Open
Abstract
Across the globe, tree species are under high anthropogenic pressure. Risks of extinction are notably more severe for species with restricted ranges and distinct evolutionary histories. Here, we use a global dataset covering 41,835 species (65.1% of known tree species) to assess the spatial pattern of tree species' phylogenetic endemism, its macroecological drivers, and how future pressures may affect the conservation status of the identified hotspots. We found that low-to-mid latitudes host most endemism hotspots, with current climate being the strongest driver, and climatic stability across thousands to millions of years back in time as a major co-determinant. These hotspots are mostly located outside of protected areas and face relatively high land-use change and future climate change pressure. Our study highlights the risk from climate change for tree diversity and the necessity to strengthen conservation and restoration actions in global hotspots of phylogenetic endemism for trees to avoid major future losses of tree diversity.
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Affiliation(s)
- Wen-Yong Guo
- Research Center for Global Change and Complex Ecosystems & Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, 200241, Shanghai, P. R. China.
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) & Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, 8000, Aarhus C, Denmark.
- Section for Ecoinformatics & Biodiversity, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark.
| | - Josep M Serra-Diaz
- Eversource Energy Center and Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
- Université de Lorraine, AgroParisTech, INRAE, Silva, Nancy, France
| | - Wolf L Eiserhardt
- Section for Ecoinformatics & Biodiversity, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
| | - Brian S Maitner
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Cory Merow
- Eversource Energy Center and Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Cyrille Violle
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Matthew J Pound
- Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, United Kingdom
| | - Miao Sun
- Section for Ecoinformatics & Biodiversity, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Ferry Slik
- Environmental and Life Sciences, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Gadong, Brunei Darussalam
| | - Anne Blach-Overgaard
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) & Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
- Section for Ecoinformatics & Biodiversity, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
| | - Brian J Enquist
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
- The Santa Fe Institute, 1399 Hyde Park Rd, Santa Fe, NM, 87501, USA
| | - Jens-Christian Svenning
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) & Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
- Section for Ecoinformatics & Biodiversity, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
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Andruchow-Colombo A, Rossetto-Harris G, Brodribb TJ, Gandolfo MA, Wilf P. A new fossil Acmopyle with accessory transfusion tissue and potential reproductive buds: Direct evidence for ever-wet rainforests in Eocene Patagonia. AMERICAN JOURNAL OF BOTANY 2023; 110:e16221. [PMID: 37598386 DOI: 10.1002/ajb2.16221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/03/2023] [Accepted: 05/05/2023] [Indexed: 08/22/2023]
Abstract
PREMISE Acmopyle (Podocarpaceae) comprises two extant species from Oceania that are physiologically restricted to ever-wet rainforests, a confirmed fossil record based on leaf adpressions and cuticles in Australia since the Paleocene, and a few uncertain reports from New Zealand, Antarctica, and South America. We investigated fossil specimens with Acmopyle affinities from the early Eocene Laguna del Hunco site in Patagonia, Argentina. METHODS We studied 42 adpression leafy-shoot fossils and included them in a total evidence phylogenetic analysis. RESULTS Acmopyle grayae sp. nov. is based on heterophyllous leafy shoots with three distinct leaf types. Among these, bilaterally flattened leaves uniquely preserve subparallel, linear features that we interpret as accessory transfusion tissue (ATT, an extra-venous water-conducting tissue). Some apical morphologies of A. grayae shoots are compatible with the early stages of ovuliferous cone development. Our phylogenetic analysis recovers the new species in a polytomy with the two extant Acmopyle species. We report several types of insect-herbivory damage. We also transfer Acmopyle engelhardti from the middle Eocene Río Pichileufú flora to Dacrycarpus engelhardti comb. nov. CONCLUSIONS We confirm the biogeographically significant presence of the endangered West Pacific genus Acmopyle in Eocene Patagonia. Acmopyle is one of the most drought-intolerant genera in Podocarpaceae, possibly due to the high collapse risk of the ATT, and thus the new fossil species provides physiological evidence for the presence of an ever-wet rainforest environment at Laguna del Hunco during the Early Eocene Climatic Optimum.
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Affiliation(s)
- Ana Andruchow-Colombo
- Museo Paleontológico Egidio Feruglio, Av. Fontana 140, Trelew, Chubut, 9100, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
- LH Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, New York, 14853, USA
| | - Gabriella Rossetto-Harris
- Department of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Timothy J Brodribb
- School of Biological Sciences, University of Tasmania, Sandy Bay, Tasmania, 7001, Australia
| | - María A Gandolfo
- Museo Paleontológico Egidio Feruglio, Av. Fontana 140, Trelew, Chubut, 9100, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
- LH Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, New York, 14853, USA
| | - Peter Wilf
- Department of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
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Wilf P, Kooyman RM. Do Southeast Asia's paleo-Antarctic trees cool the planet? THE NEW PHYTOLOGIST 2023. [PMID: 37369251 DOI: 10.1111/nph.19067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/23/2023] [Indexed: 06/29/2023]
Abstract
Many tree genera in the Malesian uplands have Southern Hemisphere origins, often supported by austral fossil records. Weathering the vast bedrock exposures in the everwet Malesian tropics may have consumed sufficient atmospheric CO2 to contribute significantly to global cooling over the past 15 Myr. However, there has been no discussion of how the distinctive regional tree assemblages may have enhanced weathering and contributed to this process. We postulate that Gondwanan-sourced tree lineages that can dominate higher-elevation forests played an overlooked role in the Neogene CO2 drawdown that led to the Ice Ages and the current, now-precarious climate state. Moreover, several historically abundant conifers in Araucariaceae and Podocarpaceae are likely to have made an outsized contribution through soil acidification that increases weathering. If the widespread destruction of Malesian lowland forests continues to spread into the uplands, the losses will threaten unique austral plant assemblages and, if our hypothesis is correct, a carbon sequestration engine that could contribute to cooler planetary conditions far into the future. Immediate effects include the spread of heat islands, significant losses of biomass carbon and forest-dependent biodiversity, erosion of watershed values, and the destruction of tens of millions of years of evolutionary history.
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Affiliation(s)
- Peter Wilf
- Department of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, 16802, USA
| | - Robert M Kooyman
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
- Research Centre for Ecosystem Resilience, Royal Botanic Gardens and Domain Trust, Sydney, NSW, 2000, Australia
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6
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Wilf P, Iglesias A, Gandolfo MA. The first Gondwanan Euphorbiaceae fossils reset the biogeographic history of the Macaranga-Mallotus clade. AMERICAN JOURNAL OF BOTANY 2023; 110:e16169. [PMID: 37128981 DOI: 10.1002/ajb2.16169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 05/03/2023]
Abstract
PREMISE The spurge family Euphorbiaceae is prominent in tropical rainforests worldwide, particularly in Asia. There is little consensus on the biogeographic origins of the family or its principal lineages. No confirmed spurge macrofossils have come from Gondwana. METHODS We describe the first Gondwanan macrofossils of Euphorbiaceae, represented by two infructescences and associated peltate leaves from the early Eocene (52 Myr ago [Ma]) Laguna del Hunco site in Chubut, Argentina. RESULTS The infructescences are panicles bearing tiny, pedicellate, spineless capsular fruits with two locules, two axile lenticular seeds, and two unbranched, plumose stigmas. The fossils' character combination only occurs today in some species of the Macaranga-Mallotus clade (MMC; Euphorbiaceae), a widespread Old-World understory group often thought to have tropical Asian origins. The associated leaves are consistent with extant Macaranga. CONCLUSIONS The new fossils are the oldest known for the MMC, demonstrating its Gondwanan history and marking its divergence by at least 52 Ma. This discovery makes an Asian origin of the MMC unlikely because immense oceanic distances separated Asia and South America 52 Ma. The only other MMC reproductive fossils so far known are also from the southern hemisphere (early Miocene, southern New Zealand), far from the Asian tropics. The MMC, along with many other Gondwanan survivors, most likely entered Asia during the Neogene Sahul-Sunda collision. Our discovery adds to a substantial series of well-dated, well-preserved fossils from one undersampled region, Patagonia, that have changed our understanding of plant biogeographic history.
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Affiliation(s)
- Peter Wilf
- Department of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, 16802, USA
| | - Ari Iglesias
- Instituto de Investigaciones en Biodiversidad y Medioambiente, Universidad Nacional del Comahue, Consejo Nacional de Investigaciones Científicas y Tecnológicas, San Carlos de Bariloche, Río Negro, R8400FRF, Argentina
| | - María A Gandolfo
- L. H. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
- Museo Paleontológico Egidio Feruglio, Consejo Nacional de Investigaciones Científicas y Técnicas, Trelew, Chubut, 9100, Argentina
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Brown MJM, Jordan GJ. No cell is an island: characterising the leaf epidermis using epidermalmorph, a new R package. THE NEW PHYTOLOGIST 2023; 237:354-366. [PMID: 36205061 PMCID: PMC10098627 DOI: 10.1111/nph.18519] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
The leaf epidermis is the interface between a plant and its environment. The epidermis is highly variable in morphology, with links to both phylogeny and environment, and this diversity is relevant to several fields, including physiology, functional traits, palaeobotany, taxonomy and developmental biology. Describing and measuring leaf epidermal traits remains challenging. Current approaches are either extremely labour-intensive and not feasible for large studies or limited to measurements of individual cells. Here, we present a method to characterise individual cell size, shape (including the effect of neighbouring cells) and arrangement from light microscope images. We provide the first automated characterisation of cell arrangement (from traced images) as well as multiple new shape characteristics. We have implemented this method in an R package, epidermalmorph, and provide an example workflow using this package, which includes functions to evaluate trait reliability and optimal sampling effort for any given group of plants. We demonstrate that our new metrics of cell shape are independent of gross cell shape, unlike existing metrics. epidermalmorph provides a broadly applicable method for quantifying epidermal traits that we hope can be used to disentangle the fundamental relationships between form and function in the leaf epidermis.
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Affiliation(s)
- Matilda J. M. Brown
- Biological SciencesUniversity of TasmaniaHobart7000Tas.Australia
- Royal Botanic Gardens KewRichmondTW9 3AEUK
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Andermann T, Strömberg CAE, Antonelli A, Silvestro D. The origin and evolution of open habitats in North America inferred by Bayesian deep learning models. Nat Commun 2022; 13:4833. [PMID: 35977931 PMCID: PMC9385654 DOI: 10.1038/s41467-022-32300-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 07/25/2022] [Indexed: 11/21/2022] Open
Abstract
Some of the most extensive terrestrial biomes today consist of open vegetation, including temperate grasslands and tropical savannas. These biomes originated relatively recently in Earth's history, likely replacing forested habitats in the second half of the Cenozoic. However, the timing of their origination and expansion remains disputed. Here, we present a Bayesian deep learning model that utilizes information from fossil evidence, geologic models, and paleoclimatic proxies to reconstruct paleovegetation, placing the emergence of open habitats in North America at around 23 million years ago. By the time of the onset of the Quaternary glacial cycles, open habitats were covering more than 30% of North America and were expanding at peak rates, to eventually become the most prominent natural vegetation type today. Our entirely data-driven approach demonstrates how deep learning can harness unexplored signals from complex data sets to provide insights into the evolution of Earth's biomes in time and space.
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Affiliation(s)
- Tobias Andermann
- Department of Organismal Biology, SciLifeLab, Uppsala University, Uppsala, Sweden.
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
- Gothenburg Global Biodiversity Centre, Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
| | - Caroline A E Strömberg
- Department of Biology & Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
| | - Alexandre Antonelli
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
- Gothenburg Global Biodiversity Centre, Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
- Department of Plant Sciences, University of Oxford, Oxford, UK
- Royal Botanic Gardens, Kew, Richmond, Surrey, UK
| | - Daniele Silvestro
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
- Gothenburg Global Biodiversity Centre, Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
- Department of Biology, University of Fribourg, Fribourg, Switzerland.
- Swiss Institute of Bioinformatics, Fribourg, Switzerland.
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Li N, Yu F, Sack D, Huang Z, Tian G, Liu S. Phytolith Assemblages as a Promising Tool for Quantitative Canopy Coverage Reconstruction in Subtropical Forests, China. FRONTIERS IN PLANT SCIENCE 2022; 13:912627. [PMID: 35795347 PMCID: PMC9251495 DOI: 10.3389/fpls.2022.912627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
This study investigates the reliability of phytolith assemblage analysis for characterizing subtropical vegetation and explores the potential for using these modern phytolith-vegetation relationships for paleoenvironmental interpretation in southeastern China. The samples were collected from five common subtropical vegetation communities in the Daiyun Mountains, southeastern China, with the above-ground vegetation recorded at each plot. Constrained ordination analysis was used to determine the most important factor governing the variations in phytolith assemblages that could be quantitatively reconstructed with weighted averaging partial least squares regression (WAPLS). The relationship between modern phytolith assemblages and the parent vegetation, as well as production, dispersal, and taphonomic processes, was discussed. Results demonstrated that the main subtropical biomes in southeastern China could be well distinguished by soil phytolith assemblages. In particular, the overall amount of tree coverage was well represented by topsoil phytolith assemblages. Grass silica short cell phytoliths (GSSCP) tended to occur in higher proportions in open habitats (shrub-meadow) at higher elevations, whereas non-grass phytolith morphotypes attained higher frequencies under mixed and broadleaf forests at lower elevations. Human-induced deforestation might increase the frequency of GSSCP within the bulk phytolith assemblage. Our results constitute the primary phytolith reference data for the subtropical zone in southeastern Asia where vegetation change during the Holocene period, particularly forest shifts, anthropogenic deforestation, and early agriculture are poorly documented.
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Affiliation(s)
- Nannan Li
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Fengling Yu
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Dorothy Sack
- Department of Geography, Ohio University, Athens, OH, United States
| | - Zhaoquan Huang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Ganghua Tian
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Shengtao Liu
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
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Fraser D, Kim SL, Welker JM, Clementz MT. Pronghorn ( Antilocapra americana) enamel phosphate δ 18O values reflect climate seasonality: Implications for paleoclimate reconstruction. Ecol Evol 2021; 11:17005-17021. [PMID: 34938488 PMCID: PMC8668790 DOI: 10.1002/ece3.8337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 11/26/2022] Open
Abstract
Stable oxygen isotope (δ18O) compositions from vertebrate tooth enamel are widely used as biogeochemical proxies for paleoclimate. However, the utility of enamel oxygen isotope values for environmental reconstruction varies among species. Herein, we evaluate the use of stable oxygen isotope compositions from pronghorn (Antilocapra americana Gray, 1866) enamel for reconstructing paleoclimate seasonality, an elusive but important parameter for understanding past ecosystems. We serially sampled the lower third molars of recent adult pronghorn from Wyoming for δ18O in phosphate (δ18OPO4) and compared patterns to interpolated and measured yearly variation in environmental waters as well as from sagebrush leaves, lakes, and rivers (δ18Ow). As expected, the oxygen isotope compositions of phosphate from pronghorn enamel are enriched in 18O relative to environmental waters. For a more direct comparison, we converted δ18Ow values into expected δ18OPO4* values (δ18OW-PO4*). Pronghorn δ18OPO4 values from tooth enamel record nearly the full amplitude of seasonal variation from Wyoming δ18OW-PO4* values. Furthermore, pronghorn enamel δ18OPO4 values are more similar to modeled δ18OW-PO4* values from plant leaf waters than meteoric waters, suggesting that they obtain much of their water from evaporated plant waters. Collectively, our findings establish that seasonality in source water is reliably reflected in pronghorn enamel, providing the basis for exploring changes in the amplitude of seasonality of ancient climates. As a preliminary test, we sampled historical pronghorn specimens (1720 ± 100 AD), which show a mean decrease (a shift to lower values) of 1-2‰ in δ18OPO4 compared to the modern specimens. They also exhibit an increase in the δ18O amplitude, representing an increase in seasonality. We suggest that the cooler mean annual and summer temperatures typical of the 18th century, as well as enhanced periods of drought, drove differences among the modern and historical pronghorn, further establishing pronghorn enamel as excellent sources of paleoclimate proxy data.
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Affiliation(s)
- Danielle Fraser
- PalaeobiologyCanadian Museum of NatureOttawaONCanada
- Department of BiologyCarleton UniversityOttawaONCanada
- Department of Earth SciencesCarleton UniversityOttawaONCanada
- Department of PaleobiologySmithsonian InstitutionNational Museum of Natural HistoryWashingtonDistrict of ColumbiaUSA
- Department of Geology and GeophysicsUniversity of WyomingLaramieWyomingUSA
| | - Sora L. Kim
- Department of Geology and GeophysicsUniversity of WyomingLaramieWyomingUSA
- Department of Life and Environmental SciencesUniversity of CaliforniaMercedCaliforniaUSA
| | - Jeffrey M. Welker
- Department of Biological SciencesUniversity of Alaska AnchorageAnchorageAlaskaUSA
- Department of Ecology and GeneticsUniversity of OuluOuluFinland
- UArcticOuluFinland
| | - Mark T. Clementz
- Department of Geology and GeophysicsUniversity of WyomingLaramieWyomingUSA
- Program in EcologyUniversity of WyomingLaramieWyomingUSA
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Milligan JN, Flynn AG, Wagner JD, Kouwenberg LL, Barclay RS, Byars BW, Dunn RE, White JD, Zechmann B, Peppe DJ. Quantifying the effect of shade on cuticle morphology and carbon isotopes of sycamores: present and past. AMERICAN JOURNAL OF BOTANY 2021; 108:2435-2451. [PMID: 34636420 PMCID: PMC9306692 DOI: 10.1002/ajb2.1772] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 09/16/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Reconstructing the light environment and architecture of the plant canopy from the fossil record requires the use of proxies, such as those derived from cell wall undulation, cell size, and carbon isotopes. All approaches assume that plant taxa will respond predictably to changes in light environments. However, most species-level studies looking at cell wall undulation only consider "sun" or "shade" leaves; therefore, we need a fully quantitative taxon-specific method. METHODS We quantified the response of cell wall undulation, cell size, and carbon isotopes of Platanus occidentalis using two experimental setups: (1) two growth chambers at low and high light and (2) a series of outdoor growth experiments using green and black shade cloth at different densities. We then developed and applied a proxy for daily light integral (DLI) to fossil Platanites leaves from two early Paleocene floras from the San Juan Basin in New Mexico. RESULTS All traits responded to light environment. Cell wall undulation was the most useful trait for reconstructing DLI in the geological record. Median reconstructed DLI from early Paleocene leaves was ~44 mol m-2 d-1 , with values from 28 to 54 mol m-2 d-1 . CONCLUSIONS Cell wall undulation of P. occidentalis is a robust, quantifiable measurement of light environment that can be used to reconstruct the paleo-light environment from fossil leaves. The distribution of high DLI values from fossil leaves may provide information on canopy architecture; indicating that either (1) most of the canopy mass is within the upper portion of the crown or (2) leaves exposed to more sunlight are preferentially preserved.
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Affiliation(s)
- Joseph N. Milligan
- Terrestrial Paleoclimatology Research Group, Department of GeosciencesBaylor UniversityWacoTXUSA
| | - Andrew G. Flynn
- Terrestrial Paleoclimatology Research Group, Department of GeosciencesBaylor UniversityWacoTXUSA
| | - Jennifer D. Wagner
- Department of Integrative BiologyUniversity of California Berkeley, and UC Museum of PaleontologyBerkeleyCAUSA
| | | | - Richard S. Barclay
- Department of PaleobiologyNational Museum of Natural History, Smithsonian Institution, 10th & Constitution Avenue NWWashingtonD.C.USA
| | | | - Regan E. Dunn
- Natural History Museums of Los Angeles County, La Brea Tar PitsLos AngelesCAUSA
| | | | - Bernd Zechmann
- Center for Microscopy and ImagingBaylor UniversityWacoTXUSA
| | - Daniel J. Peppe
- Terrestrial Paleoclimatology Research Group, Department of GeosciencesBaylor UniversityWacoTXUSA
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12
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Freeze tolerance influenced forest cover and hydrology during the Pennsylvanian. Proc Natl Acad Sci U S A 2021; 118:2025227118. [PMID: 34635589 DOI: 10.1073/pnas.2025227118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2021] [Indexed: 11/18/2022] Open
Abstract
The distribution of forest cover alters Earth surface mass and energy exchange and is controlled by physiology, which determines plant environmental limits. Ancient plant physiology, therefore, likely affected vegetation-climate feedbacks. We combine climate modeling and ecosystem-process modeling to simulate arboreal vegetation in the late Paleozoic ice age. Using GENESIS V3 global climate model simulations, varying pCO2, pO2, and ice extent for the Pennsylvanian, and fossil-derived leaf C:N, maximum stomatal conductance, and specific conductivity for several major Carboniferous plant groups, we simulated global ecosystem processes at a 2° resolution with Paleo-BGC. Based on leaf water constraints, Pangaea could have supported widespread arboreal plant growth and forest cover. However, these models do not account for the impacts of freezing on plants. According to our interpretation, freezing would have affected plants in 59% of unglaciated land during peak glacial periods and 73% during interglacials, when more high-latitude land was unglaciated. Comparing forest cover, minimum temperatures, and paleo-locations of Pennsylvanian-aged plant fossils from the Paleobiology Database supports restriction of forest extent due to freezing. Many genera were limited to unglaciated land where temperatures remained above -4 °C. Freeze-intolerance of Pennsylvanian arboreal vegetation had the potential to alter surface runoff, silicate weathering, CO2 levels, and climate forcing. As a bounding case, we assume total plant mortality at -4 °C and estimate that contracting forest cover increased net global surface runoff by up to 6.1%. Repeated freezing likely influenced freeze- and drought-tolerance evolution in lineages like the coniferophytes, which became increasingly dominant in the Permian and early Mesozoic.
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Almeida FC, Porzecanski AL, Cracraft JL, Bertelli S. The evolution of tinamous (Palaeognathae: Tinamidae) in light of molecular and combined analyses. Zool J Linn Soc 2021. [DOI: 10.1093/zoolinnean/zlab080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
The Neotropical tinamous are of particular interest in our efforts to understand the evolution of modern birds. They inhabit both forested and open environments and, although volant, have limited flight capabilities. Numerous studies have recognized the monophyly of tinamous and their relationships either as sister to the flightless ratites (ostriches, emus and their relatives) or within the ratites themselves. Despite the numerous bird phylogenies published recently, modern investigations of relationships within the tinamous themselves have been limited. Here, we present the first detailed phylogenetic analysis and divergence-date estimation including a significant number of tinamou species, both extant and fossil. The monophyly of most currently recognized polytypic genera is recovered with high support, with the exception of the paraphyletic Nothura and Nothoprocta. The traditional subdivision between those tinamous inhabiting open areas (Nothurinae) and forest environments (Tinaminae) is also confirmed. A temporal calibration of the resultant phylogeny estimates that the basal divergence of crown Tinamidae took place between 31 and 40 Mya.
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Affiliation(s)
- Francisca C Almeida
- Instituto de Ecología, Genética y Evolución (IEGEBA), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET)/ Universidad de Buenos Aires (UBA), Ciudad Autónoma de Buenos Aires, Argentina
| | - Ana L Porzecanski
- American Museum of Natural History, 200 Central Park West, New York, NY, 10024-5102, USA
| | - Joel L Cracraft
- American Museum of Natural History, 200 Central Park West, New York, NY, 10024-5102, USA
| | - Sara Bertelli
- American Museum of Natural History, 200 Central Park West, New York, NY, 10024-5102, USA
- Fundación Miguel Lillo (FML), Miguel Lillo 251, 4000 San Miguel de Tucumán, Argentina
- Unidad Ejecutora Lillo (UEL) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), San Miguel de Tucumán, Tucumán, Argentina
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Croft DA, Lorente M. No evidence for parallel evolution of cursorial limb adaptations among Neogene South American native ungulates (SANUs). PLoS One 2021; 16:e0256371. [PMID: 34403434 PMCID: PMC8370646 DOI: 10.1371/journal.pone.0256371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/04/2021] [Indexed: 11/24/2022] Open
Abstract
During the Neogene, many North American ungulates evolved longer limbs. Presumably, this allowed them to move more efficiently or quickly in open habitats, which became more common during this interval. Evidence suggests that open habitats appeared even earlier in South America, but no study to date has investigated whether the ungulate-like mammals of South America (South American native ungulates or SANUs) evolved similar limb adaptations. We analyzed limb elongation in the two predominant SANU groups, notoungulates and litopterns, by compiling genus-level occurrences from the late Oligocene to the Pleistocene and calculating metatarsal/femur ratio (Mt:F). None of the groups or subgroups we analyzed show a pronounced increase in Mt:F across this interval, with the possible exception of proterotheriid litopterns. Proterotheriids are thought to have inhabited forested environments rather than open ones, which raises questions about the selective forces responsible for limb elongation in ungulates. Conversely, notoungulates, which are traditionally thought to have lived in open habitats, show no strong trend of increasing Mt:F across this interval. Our study suggests that the macroevolutionary trend of limb elongation in ungulate-like mammals is not universal and is highly influenced by the evolutionary affinities of the groups being analyzed.
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Affiliation(s)
- Darin A. Croft
- Department of Anatomy, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
| | - Malena Lorente
- Conicet-División Paleontología Vertebrados, Museo de La Plata (UNLP), La Plata, Argentina
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15
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Rasia LL, Candela AM, Cañón C. Comprehensive total evidence phylogeny of chinchillids (Rodentia, Caviomorpha): Cheek teeth anatomy and evolution. J Anat 2021; 239:405-423. [PMID: 33721329 PMCID: PMC8273581 DOI: 10.1111/joa.13430] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 11/30/2022] Open
Abstract
Rodents are the most diverse order of extant mammals, and caviomorph rodents, or New World hystricognaths, have a remarkable morphological disparity and a long fossil record that begins in the Eocene. Chinchilloidea is a poorly understood clade within Caviomorpha, from an evolutionary and phylogenetic perspective. It includes the extant families Chinchillidae and Dinomyidae, the extinct Neoepiblemidae and Cephalomyidae, and several extinct chinchilloids without a clear phylogenetic position, like Eoincamys, Borikenomys, Chambiramys, Ucayalimys, Incamys, Saremmys, Garridomys and Scotamys. The family Chinchillidae includes the extant Chinchilla and Lagidium, grouped in Chinchillinae, and the only living Lagostominae, Lagostomus maximus. Among extinct chinchillids, Eoviscaccia (early Oligocene-early Miocene of Argentina, Bolivia and Chile), Prolagostomus (early-middle Miocene of Argentina, Bolivia and Chile) and Pliolagostomus (early-middle Miocene of Argentina) are the only genera originally described as members of the family. Based on the study of specimens with unworn or little-worn cheek teeth, belonging to extinct and extant taxa, we propose homologies of the cheek teeth structures and perform a combined molecular and morphological phylogenetic analysis including extinct and extant taxa of all families of Chinchilloidea and all genera of Chinchillidae. Our phylogenetic analysis recovered three major lineages in the evolutionary history of Chinchilloidea. The first major lineage is composed of the extant taxa Chinchilla, Lagidium and Lagostomus, and the extinct genera Eoviscaccia, Prolagostomus, Pliolagostomus, Garridomys, Incamys, Loncolicu and Saremmys. Cephalomyid (Banderomys, Cephalomys, Litodontomys, Soriamys) and neoepiblemid (Neoepiblema, Perimys, Phoberomys, Scotamys) genera are part of the second major lineage, while dinomyids such as Dinomys, Drytomomys, Scleromys, 'Scleromys' and Tetrastylus constitute the third major lineage within Chinchilloidea. The phylogenetic position of some taxa previously considered as incertae sedis chinchilloids or without a clear suprageneric group (i.e. Incamys, Saremmys, Garridomys and Loncolicu) show that they belong to pan-Chinchillidae and conform the stem Chinchillidae along with Eoviscaccia. The euhypsodont crown Chinchillidae includes the living subfamilies Chinchillinae and Lagostominae. Dinomyidae and Eoincamys pascuali are recovered as the sisters of a major clade composed by 'Cephalomyidae'+Neopiblemidae and pan-Chinchillidae, and Chambiramys sylvaticus occupies a basal position to the same clade. Four major radiation events are identified in the evolutionary history of Chinchilloidea. The analysis of new morphological characters linked with molecular evidence as well as the addition of taxa of uncertain or unstable phylogenetic position or not considered in previous studies allowed us resolve part of the relationships within Chinchilloidea, particularly that of Chinchillidae, supporting preceding morphological hypotheses.
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Affiliation(s)
- Luciano L. Rasia
- División Paleontología VertebradosMuseo de La Plata, La PlataBuenos AiresArgentina
- CONICETArgentina
| | - Adriana M. Candela
- División Paleontología VertebradosMuseo de La Plata, La PlataBuenos AiresArgentina
- CONICETArgentina
| | - Carola Cañón
- Instituto de Diversidad y Evolución Austral (IDEAus‐CONICETPuerto MadrynArgentina
- Parque Real 6SantiagoChile
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Effects of experimental warming on Betula nana epidermal cell growth tested over its maximum climatological growth range. PLoS One 2021; 16:e0251625. [PMID: 34010344 PMCID: PMC8133401 DOI: 10.1371/journal.pone.0251625] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 04/29/2021] [Indexed: 11/19/2022] Open
Abstract
Numerous long-term, free-air plant growth facilities currently explore vegetation responses to the ongoing climate change in northern latitudes. Open top chamber (OTC) experiments as well as the experimental set-ups with active warming focus on many facets of plant growth and performance, but information on morphological alterations of plant cells is still scarce. Here we compare the effects of in-situ warming on leaf epidermal cell expansion in dwarf birch, Betula nana in Finland, Greenland, and Poland. The localities of the three in-situ warming experiments represent contrasting regions of B. nana distribution, with the sites in Finland and Greenland representing the current main distribution in low and high Arctic, respectively, and the continental site in Poland as a B. nana relict Holocene microrefugium. We quantified the epidermal cell lateral expansion by microscopic analysis of B. nana leaf cuticles. The leaves were produced in paired experimental treatment plots with either artificial warming or ambient temperature. At all localities, the leaves were collected in two years at the end of the growing season to facilitate between-site and within-site comparison. The measured parameters included the epidermal cell area and circumference, and using these, the degree of cell wall undulation was calculated as an Undulation Index (UI). We found enhanced leaf epidermal cell expansion under experimental warming, except for the extremely low temperature Greenland site where no significant difference occurred between the treatments. These results demonstrate a strong response of leaf growth at individual cell level to growing season temperature, but also suggest that in harsh conditions other environmental factors may limit this response. Our results provide evidence of the relevance of climate warming for plant leaf maturation and underpin the importance of studies covering large geographical scales.
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MacPhee R, Del Pino SH, Kramarz A, Forasiepi AM, Bond M, Sulser RB. Cranial Morphology and Phylogenetic Relationships of Trigonostylops wortmani, an Eocene South American Native Ungulate. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2021. [DOI: 10.1206/0003-0090.449.1.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- R.D.E. MacPhee
- Department of Mammalogy/Vertebrate Zoology and Richard Gilder Graduate School, American Museum of Natural History
| | | | - Alejandro Kramarz
- Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales Bernardino Rivadavia, CONICET, Buenos Aires, Argentina
| | | | - Mariano Bond
- Departamento Científico de Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina
| | - R. Benjamin Sulser
- Department of Mammalogy/Vertebrate Zoology and Richard Gilder Graduate School, American Museum of Natural History
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18
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Jud NA, Gandolfo MA. Fossil evidence from South America for the diversification of Cunoniaceae by the earliest Palaeocene. ANNALS OF BOTANY 2021; 127:305-315. [PMID: 32860407 PMCID: PMC7872129 DOI: 10.1093/aob/mcaa154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/27/2020] [Indexed: 06/01/2023]
Abstract
BACKGROUND AND AIMS Cunoniaceae are woody plants with a distribution that suggests a complex history of Gondwanan vicariance, long-distance dispersal, diversification and extinction. Only four out of ~27 genera in Cunoniaceae are native to South America today, but the discovery of extinct species from Argentine Patagonia is providing new information about the history of this family in South America. METHODS We describe fossil flowers collected from early Danian (early Palaeocene, ~64 Mya) deposits of the Salamanca Formation. We compare them with similar flowers from extant and extinct species using published literature and herbarium specimens. We used simultaneous analysis of morphology and available chloroplast DNA sequences (trnL-F, rbcL, matK, trnH-psbA) to determine the probable relationship of these fossils to living Cunoniaceae and the co-occurring fossil species Lacinipetalum spectabilum. KEY RESULTS Cunoniantha bicarpellata gen. et sp. nov. is the second species of Cunoniaceae to be recognized among the flowers preserved in the Salamanca Formation. Cunoniantha flowers are pentamerous and complete, the anthers contain in situ pollen, and the gynoecium is bicarpellate and syncarpous with two free styles. Phylogenetic analysis indicates that Cunoniantha belongs to crown-group Cunoniaceae among the core Cunoniaceae clade, although it does not have obvious affinity with any tribe. Lacinipetalum spectabilum, also from the Salamanca Formation, belongs to the Cunoniaceae crown group as well, but close to tribe Schizomerieae. CONCLUSIONS Our findings highlight the importance of West Gondwana in the evolution of Cunoniaceae during the early Palaeogene. The co-occurrence of C. bicarpellata and L. spectabilum, belonging to different clades within Cunoniaceae, indicates that the diversification of crown-group Cunoniaceae was under way by 64 Mya.
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Affiliation(s)
- Nathan A Jud
- Department of Biology, William Jewell College, Liberty, MO, USA
| | - Maria A Gandolfo
- L. H. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
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Deanna R, Wilf P, Gandolfo MA. New physaloid fruit-fossil species from early Eocene South America. AMERICAN JOURNAL OF BOTANY 2020; 107:1749-1762. [PMID: 33247843 DOI: 10.1002/ajb2.1565] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 08/19/2020] [Indexed: 06/12/2023]
Abstract
PREMISE Solanaceae is a scientifically and economically important angiosperm family with a minimal fossil record and an intriguing early evolutionary history. Here, we report a newly discovered fossil lantern fruit with a suite of features characteristic of Physalideae within Solanaceae. The fossil comes from the early Eocene Laguna del Hunco site (ca. 52 Ma) in Chubut, Argentina, which previously yielded the only other physaloid fruit fossil, Physalis infinemundi. METHODS The fruit morphology and calyx venation pattern of the new fossil were compared with P. infinemundi and extant species of Solanaceae. RESULTS Physalis hunickenii sp. nov. is clearly distinct from P. infinemundi in its fruiting calyx with wider primary veins, longer and thinner lobes, and especially in its venation pattern with high density, transverse tertiary veins; these features support its placement in a new species. In comparison with extant physaloid genera, the calyx venation pattern and other diagnostic traits reinforce placement of the new fossil, like P. infinemundi, within the tribe Physalideae of Solanaceae. CONCLUSIONS Both species of fossil nightshades from Laguna del Hunco represent crown-group Solanaceae but are older than all prior age estimates of the family. Although at least 20 transoceanic dispersals have been proposed as the driver of range expansion of Solanaceae, the Patagonian fossils push back the diversification of the family to Gondwanan times. Thus, overland dispersal across Gondwana is now a likely scenario for at least some biogeographic patterns, in light of the ancient trans-Antarctic land connections between South America and Australia.
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Affiliation(s)
- Rocío Deanna
- Instituto Multidisciplinario de Biología Vegetal, IMBIV (CONICET-UNC), CC 495, Córdoba, 5000, Argentina
- Departamento de Ciencias Farmacéuticas, Facultad de Ciencias Químicas (FCQ, UNC), Medina Allende s.n., Córdoba, 5000, Argentina
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, 80305, USA
| | - Peter Wilf
- Department of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Maria A Gandolfo
- L.H. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York, 14853, USA
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Brightly WH, Hartley SE, Osborne CP, Simpson KJ, Strömberg CAE. High silicon concentrations in grasses are linked to environmental conditions and not associated with C 4 photosynthesis. GLOBAL CHANGE BIOLOGY 2020; 26:7128-7143. [PMID: 32897634 DOI: 10.1111/gcb.15343] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
The uptake and deposition of silicon (Si) as silica phytoliths is common among land plants and is associated with a variety of functions. Among these, herbivore defense has received significant attention, particularly with regard to grasses and grasslands. Grasses are well known for their high silica content, a trait which has important implications ranging from defense to global Si cycling. Here, we test the classic hypothesis that C4 grasses evolved stronger mechanical defenses than C3 grasses through increased phytolith deposition, in response to extensive ungulate herbivory ("C4 -grazer hypothesis"). Despite mixed support, this hypothesis has received broad attention, even outside the realm of plant biology. Because C3 and C4 grasses typically dominate in different climates, with the latter more abundant in hot, dry regions, we also investigated the effects of water availability and temperature on Si deposition. We compiled a large dataset of grasses grown under controlled environmental conditions. Using phylogenetically informed generalized linear mixed models and character evolution models, we evaluated whether photosynthetic pathway or growth condition influenced Si concentration. We found that C4 grasses did not show consistently elevated Si concentrations compared with C3 grasses. High temperature treatments were associated with increased concentration, especially in taxa adapted to warm regions. Although the effect was less pronounced, reduced water treatment also promoted silica deposition, with slightly stronger response in dry habitat species. The evidence presented here rejects the "C4 -grazer hypothesis." Instead, we propose that the tendency for C4 grasses to outcompete C3 species under hot, dry conditions explains previous observations supporting this hypothesis. These findings also suggest a mechanism via which anthropogenic climate change may influence silica deposition in grasses and, by extension, alter the important ecological and geochemical processes it affects.
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Affiliation(s)
- William H Brightly
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
| | - Sue E Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Colin P Osborne
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Kimberley J Simpson
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Caroline A E Strömberg
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
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Persistent biotic interactions of a Gondwanan conifer from Cretaceous Patagonia to modern Malesia. Commun Biol 2020; 3:708. [PMID: 33239710 PMCID: PMC7689466 DOI: 10.1038/s42003-020-01428-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 10/22/2020] [Indexed: 11/09/2022] Open
Abstract
Many plant genera in the tropical West Pacific are survivors from the paleo-rainforests of Gondwana. For example, the oldest fossils of the Malesian and Australasian conifer Agathis (Araucariaceae) come from the early Paleocene and possibly latest Cretaceous of Patagonia, Argentina (West Gondwana). However, it is unknown whether dependent ecological guilds or lineages of associated insects and fungi persisted on Gondwanan host plants like Agathis through time and space. We report insect-feeding and fungal damage on Patagonian Agathis fossils from four latest Cretaceous to middle Eocene floras spanning ca. 18 Myr and compare it with damage on extant Agathis. Very similar damage was found on fossil and modern Agathis, including blotch mines representing the first known Cretaceous-Paleogene boundary crossing leaf-mine association, external foliage feeding, galls, possible armored scale insect (Diaspididae) covers, and a rust fungus (Pucciniales). The similar suite of damage, unique to fossil and extant Agathis, suggests persistence of ecological guilds and possibly the component communities associated with Agathis since the late Mesozoic, implying host tracking of the genus across major plate movements that led to survival at great distances. The living associations, mostly made by still-unknown culprits, point to previously unrecognized biodiversity and evolutionary history in threatened rainforest ecosystems.
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Cheesman AW, Duff H, Hill K, Cernusak LA, McInerney FA. Isotopic and morphologic proxies for reconstructing light environment and leaf function of fossil leaves: a modern calibration in the Daintree Rainforest, Australia. AMERICAN JOURNAL OF BOTANY 2020; 107:1165-1176. [PMID: 32864740 DOI: 10.1002/ajb2.1523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 04/28/2020] [Indexed: 06/11/2023]
Abstract
PREMISE Within closed-canopy forests, vertical gradients of light and atmospheric CO2 drive variations in leaf carbon isotope ratios, leaf mass per area (LMA), and the micromorphology of leaf epidermal cells. Variations in traits observed in preserved or fossilized leaves could enable inferences of past forest canopy closure and leaf function and thereby habitat of individual taxa. However, as yet no calibration study has examined how isotopic, micro- and macromorphological traits, in combination, reflect position within a modern closed-canopy forest or how these could be applied to the fossil record. METHODS Leaves were sampled from throughout the vertical profile of the tropical forest canopy using the 48.5 m crane at the Daintree Rainforest Observatory, Queensland, Australia. Carbon isotope ratios, LMA, petiole metric (i.e., petiole-width2 /leaf area, a proposed proxy for LMA that can be measured from fossil leaves), and leaf micromorphology (i.e., undulation index and cell area) were compared within species across a range of canopy positions, as quantified by leaf area index (LAI). RESULTS Individually, cell area, δ13 C, and petiole metric all correlated with both LAI and LMA, but the use of a combined model provided significantly greater predictive power. CONCLUSIONS Using the observed relationships with leaf carbon isotope ratio and morphology to estimate the range of LAI in fossil floras can provide a measure of canopy closure in ancient forests. Similarly, estimates of LAI and LMA for individual taxa can provide comparative measures of light environment and growth strategy of fossil taxa from within a flora.
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Affiliation(s)
- Alexander W Cheesman
- College of Science and Engineering and Centre for Tropical Environmental and Sustainability Science, James Cook University, Cairns, Australia
- University of Exeter, CEMPS, Exeter EX4 4QE, Devon, England
| | - Heather Duff
- Sprigg Geobiology Centre and Department of Earth Sciences, The University of Adelaide, Adelaide, Australia
| | - Kathryn Hill
- Department of Ecology and Evolutionary Biology, The University of Adelaide, Adelaide, Australia
| | - Lucas A Cernusak
- College of Science and Engineering and Centre for Tropical Environmental and Sustainability Science, James Cook University, Cairns, Australia
| | - Francesca A McInerney
- Sprigg Geobiology Centre and Department of Earth Sciences, The University of Adelaide, Adelaide, Australia
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Li Y, Reich PB, Schmid B, Shrestha N, Feng X, Lyu T, Maitner BS, Xu X, Li Y, Zou D, Tan Z, Su X, Tang Z, Guo Q, Feng X, Enquist BJ, Wang Z. Leaf size of woody dicots predicts ecosystem primary productivity. Ecol Lett 2020; 23:1003-1013. [PMID: 32249502 PMCID: PMC7384143 DOI: 10.1111/ele.13503] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 01/20/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023]
Abstract
A key challenge in ecology is to understand the relationships between organismal traits and ecosystem processes. Here, with a novel dataset of leaf length and width for 10 480 woody dicots in China and 2374 in North America, we show that the variation in community mean leaf size is highly correlated with the variation in climate and ecosystem primary productivity, independent of plant life form. These relationships likely reflect how natural selection modifies leaf size across varying climates in conjunction with how climate influences canopy total leaf area. We find that the leaf size-primary productivity functions based on the Chinese dataset can predict productivity in North America and vice-versa. In addition to advancing understanding of the relationship between a climate-driven trait and ecosystem functioning, our findings suggest that leaf size can also be a promising tool in palaeoecology for scaling from fossil leaves to palaeo-primary productivity of woody ecosystems.
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Affiliation(s)
- Yaoqi Li
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
| | - Peter B. Reich
- Department of Forest ResourcesUniversity of MinnesotaSt. PaulMN55108USA
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSW2751Australia
| | - Bernhard Schmid
- Department of GeographyRemote Sensing LaboratoriesUniversity of ZurichWinterthurerstrasse 1908057ZurichSwitzerland
| | - Nawal Shrestha
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
- Institute of Innovation EcologyLanzhou UniversityLanzhou730000China
| | - Xiao Feng
- Institute of the EnvironmentUniversity of ArizonaTucsonArizona85721USA
| | - Tong Lyu
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
| | - Brian S. Maitner
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonAZ85721USA
| | - Xiaoting Xu
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
- Key Laboratory of Bio‐Resource and Eco‐Environment of Ministry of EducationCollege of Life SciencesSichuan UniversityChengdu610065SichuanChina
| | - Yichao Li
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
| | - Dongting Zou
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
| | - Zheng‐Hong Tan
- College of Environment and EcologyHainan UniversityHaikouHainan570228China
| | - Xiangyan Su
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
| | - Zhiyao Tang
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
| | - Qinghua Guo
- State Key Laboratory of Vegetation and Environmental ChangeInstitute of BotanyChinese Academy of SciencesBeijing100093China
| | - Xiaojuan Feng
- State Key Laboratory of Vegetation and Environmental ChangeInstitute of BotanyChinese Academy of SciencesBeijing100093China
| | - Brian J. Enquist
- Institute of the EnvironmentUniversity of ArizonaTucsonArizona85721USA
- The Santa Fe InstituteSanta FeNM87501USA
| | - Zhiheng Wang
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China
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Li P, Morse PE, Kay RF. Dental topographic change with macrowear and dietary inference in Homunculus patagonicus. J Hum Evol 2020; 144:102786. [PMID: 32402847 DOI: 10.1016/j.jhevol.2020.102786] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 03/15/2020] [Accepted: 03/16/2020] [Indexed: 11/24/2022]
Abstract
Homunculus patagonicus is a stem platyrrhine from the late Early Miocene, high-latitude Santa Cruz Formation, Argentina. Its distribution lies farther south than any extant platyrrhine species. Prior studies on the dietary specialization of Homunculus suggest either a mixed diet of fruit and leaves or a more predominantly fruit-eating diet. To gain further insight into the diet of Homunculus, we examined how the occlusal surfaces of the first and second lower molars of Homunculus change with wear by using three homology-free dental topographic measures: Dirichlet normal energy (DNE), orientation patch count rotated (OPCR), and relief index (RFI). We compared these data with wear series of three extant platyrrhine taxa: the folivorous Alouatta, and the frugivorous Ateles and Callicebus (titi monkeys now in the genus Plecturocebus). Previous studies found Alouatta and Ateles exhibit distinctive patterns of change in occlusal morphology with macrowear, possibly related to the more folivorous diet of the former. Based on previous suggestions that Homunculus was at least partially folivorous, we predicted that changes in dental topographic metrics with wear would follow a pattern more similar to that seen in Alouatta than in Ateles or Callicebus. However, wear-induced changes in Homunculus crown sharpness (DNE) and complexity (OPCR) are more similar to the pattern observed in the frugivorous Ateles and Callicebus. Based on similar wear modalities of the lower molars between Homunculus and Callicebus, we infer that Homunculus had a primarily frugivorous diet. Leaves may have provided an alternative dietary resource to accommodate fluctuation in seasonal fruiting abundance in the high-latitude extratropical environment of late Early Miocene Patagonia.
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Affiliation(s)
- Peishu Li
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago IL, USA; Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, USA; Department of Biology, Duke University, Durham, NC, USA.
| | - Paul E Morse
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA; Florida Museum of Natural History, University of Florida, Gainesville, FL, USA
| | - Richard F Kay
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, USA; Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
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Holland BR, Ketelaar-Jones S, O'Mara AR, Woodhams MD, Jordan GJ. Accuracy of ancestral state reconstruction for non-neutral traits. Sci Rep 2020; 10:7644. [PMID: 32376845 PMCID: PMC7203120 DOI: 10.1038/s41598-020-64647-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 04/09/2020] [Indexed: 12/05/2022] Open
Abstract
The assumptions underpinning ancestral state reconstruction are violated in many evolutionary systems, especially for traits under directional selection. However, the accuracy of ancestral state reconstruction for non-neutral traits is poorly understood. To investigate the accuracy of ancestral state reconstruction methods, trees and binary characters were simulated under the BiSSE (Binary State Speciation and Extinction) model using a wide range of character-state-dependent rates of speciation, extinction and character-state transition. We used maximum parsimony (MP), BiSSE and two-state Markov (Mk2) models to reconstruct ancestral states. Under each method, error rates increased with node depth, true number of state transitions, and rates of state transition and extinction; exceeding 30% for the deepest 10% of nodes and highest rates of extinction and character-state transition. Where rates of character-state transition were asymmetrical, error rates were greater when the rate away from the ancestral state was largest. Preferential extinction of species with the ancestral character state also led to higher error rates. BiSSE outperformed Mk2 in all scenarios where either speciation or extinction was state dependent and outperformed MP under most conditions. MP outperformed Mk2 in most scenarios except when the rates of character-state transition and/or extinction were highly asymmetrical and the ancestral state was unfavoured.
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Affiliation(s)
- Barbara R Holland
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia.
| | - Saan Ketelaar-Jones
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia
| | - Aidan R O'Mara
- School of Health Sciences, University of Tasmania, Private Bag 121, Hobart, Tas, 7001, Australia
| | - Michael D Woodhams
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia
| | - Gregory J Jordan
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia
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26
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Rossetto-Harris G, Wilf P, Escapa IH, Andruchow-Colombo A. Eocene Araucaria Sect. Eutacta from Patagonia and floristic turnover during the initial isolation of South America. AMERICAN JOURNAL OF BOTANY 2020; 107:806-832. [PMID: 32388874 DOI: 10.1002/ajb2.1467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/12/2020] [Indexed: 06/11/2023]
Abstract
PREMISE Eocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genus Araucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to Australasian Araucaria Sect. Eutacta usually are represented by isolated organs, making diagnosis difficult. Araucaria pichileufensis E.W. Berry, from the middle Eocene Río Pichileufú (RP) site in Argentine Patagonia, was originally placed in Sect. Eutacta and later reported from the early Eocene Laguna del Hunco (LH) locality. However, the relationship of A. pichileufensis to Sect. Eutacta and the conspecificity of the Araucaria material among these Patagonian floras have not been tested using modern methods. METHODS We review the type material of A. pichileufensis alongside large (n = 192) new fossil collections of Araucaria from LH and RP, including multi-organ preservation of leafy branches, ovuliferous complexes, and pollen cones. We use a total evidence phylogenetic analysis to analyze relationships of the fossils to Sect. Eutacta. RESULTS We describe Araucaria huncoensis sp. nov. from LH and improve the whole-plant concept for Araucaria pichileufensis from RP. The two species respectively resolve in the crown and stem of Sect. Eutacta. CONCLUSIONS Our results confirm the presence and indicate the survival of Sect. Eutacta in South America during early Antarctic separation. The exceptionally complete fossils significantly predate several molecular age estimates for crown Eutacta. The differentiation of two Araucaria species demonstrates conifer turnover during climate change and initial South American isolation from the early to middle Eocene.
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Affiliation(s)
| | - Peter Wilf
- Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Ignacio H Escapa
- Museo Paleontológico Egidio Feruglio, Consejo Nacional de Investigaciones Científicas y Técnicas, Trelew, 9100, Chubut, Argentina
| | - Ana Andruchow-Colombo
- Museo Paleontológico Egidio Feruglio, Consejo Nacional de Investigaciones Científicas y Técnicas, Trelew, 9100, Chubut, Argentina
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27
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Silicon and Plant-Animal Interactions: Towards an Evolutionary Framework. PLANTS 2020; 9:plants9040430. [PMID: 32244583 PMCID: PMC7238073 DOI: 10.3390/plants9040430] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 12/16/2022]
Abstract
Herbivory is fundamental in ecology, being a major driver of ecosystem structure and functioning. Plant Si and phytoliths play a significant antiherbivory role, the understanding of which and of its evolutionary context will increase our understanding of this phenomenon, its origins, and its significance for past, extant, and future ecosystems. To achieve this goal, we need a superdisciplinary evolutionary framework connecting the role of Si in plant–herbivore interactions, in global processes, and in plant and herbivore evolution. To do this properly, we should acknowledge and incorporate into our work some basic facts that are too often overlooked. First, there is great taxonomic variance both in plant Si contents, forms, and roles, but also in herbivore responses, dietary preferences, and in fossil evidence. Second, species and their traits, as well as whole ecosystems, should be seen in the context of their entire evolutionary history and may therefore reflect not only adaptations to extant selective factors but also anachronistic traits. Third, evolutionary history and evolutionary transitions are complex, resulting in true and apparent asynchronisms. Fourth, evolution and ecology are multiscalar, in which various phenomena and processes act at various scales. Taking these issues into consideration will improve our ability to develop this needed theoretical framework and will bring us closer to gaining a more complete understanding of one of the most exciting and elusive phenomena in plant biology and ecology.
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28
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Ge Y, Lu H, Zhang J, Wang C, Gao X. Phytoliths in Inflorescence Bracts: Preliminary Results of an Investigation on Common Panicoideae Plants in China. FRONTIERS IN PLANT SCIENCE 2020; 10:1736. [PMID: 32153596 PMCID: PMC7044271 DOI: 10.3389/fpls.2019.01736] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 12/10/2019] [Indexed: 06/10/2023]
Abstract
Phytoliths in the inflorescence of Poaceae plants can be of high taxonomic value in some archaeological contexts and provide insight into plant taxonomy and crop domestication processes. In this study, phytoliths in every inflorescence bract of 38 common Panicoideae weeds and minor crops in China were studied. Based on dissection of the inflorescence into different bracts using a treatment that retained the phytoliths anatomical position, observations of inflorescence phytoliths types and distribution were described in detail. We found that Interdigitating, Blocky amoeboid, Rectangular dentate, and Elongate dendritic with multi tent-like arch tops were of higher taxonomic value than the other types in our studied species. Both morphological and morphometric traits of the Interdigitating were summarized and compared with previous studies; the findings suggested that genus level discrimination of some Paniceae species could be reliable, and tribe/species level discrimination might be feasible. The phytoliths in the involucre of domesticated and wild type Coix lacryma-jobi provided insight into the domestication process of this plant. Our data also indicated that phytolith production in the inflorescence bracts might be under the genetic and molecular control of inflorescence development. Thus, the findings of this study could assist future studies in plant taxonomy and archaeobotany.
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Affiliation(s)
- Yong Ge
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
| | - Houyuan Lu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Tibetan Plateau Earth Science, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jianping Zhang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Tibetan Plateau Earth Science, Chinese Academy of Sciences, Beijing, China
| | - Can Wang
- Department of Archaeology, School of History and Culture, Shandong University, Jinan, China
| | - Xing Gao
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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29
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Jordan GJ, Carpenter RJ, Holland BR, Beeton NJ, Woodhams MD, Brodribb TJ. Links between environment and stomatal size through evolutionary time in Proteaceae. Proc Biol Sci 2020; 287:20192876. [PMID: 31992170 DOI: 10.1098/rspb.2019.2876] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The size of plant stomata (adjustable pores that determine the uptake of CO2 and loss of water from leaves) is considered to be evolutionarily important. This study uses fossils from the major Southern Hemisphere family Proteaceae to test whether stomatal cell size responded to Cenozoic climate change. We measured the length and abundance of guard cells (the cells forming stomata), the area of epidermal pavement cells, stomatal index and maximum stomatal conductance from a comprehensive sample of fossil cuticles of Proteaceae, and extracted published estimates of past temperature and atmospheric CO2. We developed a novel test based on stochastic modelling of trait evolution to test correlations among traits. Guard cell length increased, and stomatal density decreased significantly with decreasing palaeotemperature. However, contrary to expectations, stomata tended to be smaller and more densely packed at higher atmospheric CO2. Thus, associations between stomatal traits and palaeoclimate over the last 70 million years in Proteaceae suggest that stomatal size is significantly affected by environmental factors other than atmospheric CO2. Guard cell length, pavement cell area, stomatal density and stomatal index covaried in ways consistent with coordinated development of leaf tissues.
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Affiliation(s)
- Gregory J Jordan
- Discipline of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Raymond J Carpenter
- Discipline of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.,School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Barbara R Holland
- ARC Centre of Excellence for Plant Success, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.,Discipline of Mathematics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia
| | - Nicholas J Beeton
- Discipline of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.,Discipline of Mathematics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia.,CSIRO, Castray Esplanade, Battery Point, Tasmania 7004, Australia
| | - Michael D Woodhams
- Discipline of Mathematics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia
| | - Timothy J Brodribb
- Discipline of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.,ARC Centre of Excellence for Plant Success, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
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30
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Álvarez A, Ercoli MD, Verzi DH. Integration and diversity of the caviomorph mandible (Rodentia: Hystricomorpha): assessing the evolutionary history through fossils and ancestral shape reconstructions. Zool J Linn Soc 2019. [DOI: 10.1093/zoolinnean/zlz071] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractCaviomorph rodents constitute a highly diverse clade of Neotropical mammals. They are recorded since at least the late Middle Eocene and have a long and complex evolutionary history. Using geometric morphometric data, we analysed the variation in mandibular shape of this clade through integration analyses, allometry and shape optimizations onto a phylogenetic tree of 104 extant and extinct species. The analyses of shape variation revealed a strong influence of phylogenetic structure and life habits. A remarkable allometric effect was observed for specific mandibular traits. Morphological changes occurring in the alveolar and muscular functional units were moderately associated. Interestingly, the coordinated evolution of these two functional units was decoupled in the clade of extant abrocomids. A sequential and nearly synchronic acquisition of convergent traits has occurred in chinchillids and derived cavioids since at least the early Middle Oligocene, probably derived from grass-feeding habits or similar adaptations to other abrasive items. Convergences between fossorial taxa evolved in two main events through the Oligocene and middle Late Miocene. Morphological analysis of the fossil representatives allowed a better understanding of the timing of trait acquisitions during the evolutionary history of caviomorphs and its relationship with global and regional palaeoenvironmental changes.
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Affiliation(s)
- Alicia Álvarez
- Instituto de Ecorregiones Andinas (INECOA), Universidad Nacional de Jujuy, CONICET, IdGyM, San Salvador de Jujuy, Jujuy, Argentina
| | - Marcos D Ercoli
- Instituto de Ecorregiones Andinas (INECOA), Universidad Nacional de Jujuy, CONICET, IdGyM, San Salvador de Jujuy, Jujuy, Argentina
| | - Diego H Verzi
- Sección Mastozoología, Museo de La Plata, CONICET, La Plata, Buenos Aires, Argentina
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31
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Acuña Castillo R, Luebert F, Henning T, Weigend M. Major lineages of Loasaceae subfam. Loasoideae diversified during the Andean uplift. Mol Phylogenet Evol 2019; 141:106616. [PMID: 31520779 DOI: 10.1016/j.ympev.2019.106616] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 12/14/2022]
Abstract
The Loasoideae is the largest clade in the Loasaceae. This subfamily is widespread throughout the Neotropics and centered in the Andes, presenting an excellent opportunity to study diversification across much of temperate and mid to high-elevation areas of South America. Despite that, no studies have addressed the historical biogeography of the Loasoideae to date, leaving an important knowledge gap in this plant group. Here, we used four plastid markers (i.e., trnL-trnF, matK, trnS-trnG, and rps16) and sequenced 170 accessions (134 ingroup taxa) to infer the phylogeny of Loasoideae. We then used this phylogeny as basis to estimate divergence times using an uncorrelated relaxed molecular clock approach and seven fossils as primary calibration points. We employed the Dispersal-Extinction-Cladogenesis (DEC) approach to reconstruct the ancestral ranges of the subfamily. Our results indicate that stem Loasoideae diverged from its sister group in the Late Cretaceous to Early Paleocene (ca. 83-62 Ma). The crown node of the whole clade goes back to the Middle Paleocene to Middle Eocene (ca. 60-45 Ma), corresponding to the earliest diversification events of the extant groups, prior to most of the Andean orogeny and roughly coinciding with the Paleocene-Eocene Thermal Maximum. On the other hand, the crown nodes of most genera appear to have originated in the Oligocene and Miocene (median ages: 28-10 Ma). The diversification of some extant lineages appears to have happened in parallel to Andean uplift pulses that seem to have had an effect on the orogeny and concomitant establishment of new habitats and latitudinal corridors. The most likely ancestral areas retrieved for crown Loasoideae, are the tropical Andes and Pacific arid coast. Most of the extant clades have remained restricted to their ancestral areas. Transoceanic Long Distance Dispersal appears to have been involved in the arrival of Loasoid ancestors to South America, and in the distribution of the small clades Kissenia in Africa and Plakothira on the Marquesas Archipelago. The results presented here suggest that the historical biogeography of the continental scale radiation of Loasoideae, follows the sequence and timing of the development of temperate and mid to high-elevation habitats across South America during the Tertiary.
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Affiliation(s)
- Rafael Acuña Castillo
- Universität Bonn, Nees-Institut für Biodiversität der Pflanzen, Meckenheimer Allee 170, 53115 Bonn, Germany; Universidad de Costa Rica, Escuela de Biología, Apdo. Postal: 11501-2060 San Pedro de Montes de Oca, Costa Rica.
| | - Federico Luebert
- Universität Bonn, Nees-Institut für Biodiversität der Pflanzen, Meckenheimer Allee 170, 53115 Bonn, Germany; Universidad de Chile, Departamento de Silvicultura y Conservación de la Naturaleza, Santiago, Chile
| | - Tilo Henning
- Freie Universität Berlin, Botanischer Garten Botanisches Museum, Königin-Luise-Straße 6-8, 14195 Berlin, Germany
| | - Maximilian Weigend
- Universität Bonn, Nees-Institut für Biodiversität der Pflanzen, Meckenheimer Allee 170, 53115 Bonn, Germany
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32
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Delsuc F, Kuch M, Gibb GC, Karpinski E, Hackenberger D, Szpak P, Martínez JG, Mead JI, McDonald HG, MacPhee RDE, Billet G, Hautier L, Poinar HN. Ancient Mitogenomes Reveal the Evolutionary History and Biogeography of Sloths. Curr Biol 2019; 29:2031-2042.e6. [PMID: 31178321 DOI: 10.1016/j.cub.2019.05.043] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/18/2019] [Accepted: 05/15/2019] [Indexed: 12/20/2022]
Abstract
Living sloths represent two distinct lineages of small-sized mammals that independently evolved arboreality from terrestrial ancestors. The six extant species are the survivors of an evolutionary radiation marked by the extinction of large terrestrial forms at the end of the Quaternary. Until now, sloth evolutionary history has mainly been reconstructed from phylogenetic analyses of morphological characters. Here, we used ancient DNA methods to successfully sequence 10 extinct sloth mitogenomes encompassing all major lineages. This includes the iconic continental ground sloths Megatherium, Megalonyx, Mylodon, and Nothrotheriops and the smaller endemic Caribbean sloths Parocnus and Acratocnus. Phylogenetic analyses identify eight distinct lineages grouped in three well-supported clades, whose interrelationships are markedly incongruent with the currently accepted morphological topology. We show that recently extinct Caribbean sloths have a single origin but comprise two highly divergent lineages that are not directly related to living two-fingered sloths, which instead group with Mylodon. Moreover, living three-fingered sloths do not represent the sister group to all other sloths but are nested within a clade of extinct ground sloths including Megatherium, Megalonyx, and Nothrotheriops. Molecular dating also reveals that the eight newly recognized sloth families all originated between 36 and 28 million years ago (mya). The early divergence of recently extinct Caribbean sloths around 35 mya is consistent with the debated GAARlandia hypothesis postulating the existence at that time of a biogeographic connection between northern South America and the Greater Antilles. This new molecular phylogeny has major implications for reinterpreting sloth morphological evolution, biogeography, and diversification history.
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Affiliation(s)
- Frédéric Delsuc
- Institut des Sciences de l'Evolution de Montpellier (ISEM), CNRS, IRD, EPHE, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.
| | - Melanie Kuch
- McMaster Ancient DNA Centre, Departments of Anthropology and Biochemistry, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada
| | - Gillian C Gibb
- Institut des Sciences de l'Evolution de Montpellier (ISEM), CNRS, IRD, EPHE, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France; Wildlife and Ecology Group, School of Agriculture and Environment, Massey University, Centennial Drive, Hokowhitu, Palmerston North 4410, New Zealand
| | - Emil Karpinski
- McMaster Ancient DNA Centre, Departments of Anthropology and Biochemistry, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada; Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada
| | - Dirk Hackenberger
- McMaster Ancient DNA Centre, Departments of Anthropology and Biochemistry, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada
| | - Paul Szpak
- Department of Anthropology, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada
| | - Jorge G Martínez
- Instituto Superior de Estudios Sociales, CONICET-Instituto de Arqueología y Museo, Universidad Nacional de Tucumán, San Martín 1545, CP4000 San Miguel de Tucumán, Argentina
| | - Jim I Mead
- The Mammoth Site, Hot Springs, Hot Springs, SD 57747, USA; East Tennessee State University Natural History Museum, 1212 Suncrest Drive, Johnson City, TN 37615, USA
| | - H Gregory McDonald
- Bureau of Land Management, Utah State Office, 440 West 200 South #500, Salt Lake City, UT 84101, USA
| | - Ross D E MacPhee
- Division of Vertebrate Zoology/Mammalogy, American Museum of Natural History, Central Park West & 79th Street, New York, NY 10024, USA
| | - Guillaume Billet
- Centre de Recherche en Paléontologie - Paris (CR2P), UMR CNRS 7207, Sorbonne Université, Muséum National d'Histoire Naturelle, 57 Rue Cuvier, 75005 Paris, France
| | - Lionel Hautier
- Institut des Sciences de l'Evolution de Montpellier (ISEM), CNRS, IRD, EPHE, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France; Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
| | - Hendrik N Poinar
- McMaster Ancient DNA Centre, Departments of Anthropology and Biochemistry, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada.
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Evolutive Implications of Megathericulus patagonicus (Xenarthra, Megatheriinae) from the Miocene of Patagonia Argentina. J MAMM EVOL 2019. [DOI: 10.1007/s10914-019-09469-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Eldridge MDB, Beck RMD, Croft DA, Travouillon KJ, Fox BJ. An emerging consensus in the evolution, phylogeny, and systematics of marsupials and their fossil relatives (Metatheria). J Mammal 2019. [DOI: 10.1093/jmammal/gyz018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Mark D B Eldridge
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Robin M D Beck
- School of Environment and Life Sciences, University of Salford, Manchester, United Kingdom
| | - Darin A Croft
- School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | | | - Barry J Fox
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia
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35
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Modeling the Stereoscopic Features of Mountainous Forest Landscapes for the Extraction of Forest Heights from Stereo Imagery. REMOTE SENSING 2019. [DOI: 10.3390/rs11101222] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Spaceborne stereoscopic systems have been growing in recent years, and the point cloud extracted from spaceborne stereo imagery has been used to measure forest spatial structures. These systems work on different viewing angles and image spatial resolutions, which are two critical factors determining the quality of the derived point cloud. In addition, the complex terrain is also a great challenge for the regional mapping of forest spatial structures using spaceborne stereo imagery. Although several theoretical models for simulating multi-view spectral features of forest canopies have been developed, there is hardly any report of a stereoscopic analysis using these models due to the limited size of the simulated forest scenes and the lack of a geometric sensory model (i.e., physical relationship between two-dimensional image coordinates and three-dimensional georeferenced coordinates). The stereoscopic features (i.e., parallax) are, as important as the spectral features contained in the multi-view images of a targeted area, the basis for the extraction of a point cloud. In this study, a new model, referred to as LandStereo model, has been proposed, which is capable of simulating the stereoscopic features of forest canopies over mountainous areas at landscape scales. The model comprised five parts, including defining the mountainous forest landscapes, setting the sun-senor observation geometry, simulating images, generating ground control points, and building geometric sensor models. The LandStereo model was validated over three different scenes, including flat forest landscapes, bare mountain landscapes, and mountainous forest landscapes. The results clearly demonstrated that the LandStereo model worked well on simulating stereoscopic features of both terrains and forest canopies at landscape scales. The extracted height of a forest canopy top from simulated stereo imagery was highly correlated to the truth (R2 = 0.96 and RMSE = 0.99 m) over the flat terrains and (R2 = 0.92 and RMSE = 1.15 m) over the mountainous areas. The LandStereo model provided a powerful tool to further our understanding of the relationships between forest spatial structures and point cloud extracted from stereo imagery acquired from different view angles and spatial resolutions under complex terrain conditions.
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36
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Ecological and hydroclimate responses to strengthening of the Hadley circulation in South America during the Late Miocene cooling. Proc Natl Acad Sci U S A 2019; 116:9747-9752. [PMID: 31036635 DOI: 10.1073/pnas.1810721116] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Near-modern ecosystems were established as a result of rapid ecological adaptation and climate change in the Late Miocene. On land, Late Miocene aridification spread in tandem with expansion of open habitats including C4 grassland ecosystems. Proxy records for the central Andes spanning the Late Miocene cooling (LMC) show the reorganization of subtropical ecosystems and hydroclimate in South America between 15 and 35°S. Continental pedogenic carbonates preserved in Neogene basins record a general increase of δ18O and δ13C values from pre-LMC to post-LMC, most robustly occurring in the subtropics (25 to 30°S), suggesting aridification and a shift toward a more C4-plant-dominated ecosystem. These changes are closely tied to the enhancement of the Hadley circulation and moisture divergence away from the subtropics toward the Intertropical Convergence Zone as revealed by climate model simulations with prescribed sea-surface temperatures (SSTs) reflecting different magnitudes of LMC steepening of equator-to-pole temperature gradient and CO2 decline.
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37
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Semprebon GM, Rivals F, Janis CM. The Role of Grass vs. Exogenous Abrasives in the Paleodietary Patterns of North American Ungulates. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00065] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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38
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Evolutionary and Functional Implications of Incisor Enamel Microstructure Diversity in Notoungulata (Placentalia, Mammalia). J MAMM EVOL 2019. [DOI: 10.1007/s10914-019-09462-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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39
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Vőfély RV, Gallagher J, Pisano GD, Bartlett M, Braybrook SA. Of puzzles and pavements: a quantitative exploration of leaf epidermal cell shape. THE NEW PHYTOLOGIST 2019; 221:540-552. [PMID: 30281798 PMCID: PMC6585845 DOI: 10.1111/nph.15461] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 08/21/2018] [Indexed: 05/18/2023]
Abstract
Epidermal cells of leaves are diverse: tabular pavement cells, trichomes, and stomatal complexes. Pavement cells from the monocot Zea mays (maize) and the eudicot Arabidopsis thaliana (Arabidopsis) have highly undulate anticlinal walls. The molecular basis for generating these undulating margins has been extensively investigated in these species. This has led to two assumptions: first, that particular plant lineages are characterized by particular pavement cell shapes; and second, that undulatory cell shapes are common enough to be model shapes. To test these assumptions, we quantified pavement cell shape in epidermides from the leaves of 278 vascular plant taxa. We found that monocot pavement cells tended to have weakly undulating margins, fern cells had strongly undulating margins, and eudicot cells showed no particular undulation degree. Cells with highly undulating margins, like those of Arabidopsis and maize, were in the minority. We also found a trend towards more undulating cell margins on abaxial leaf surfaces; and that highly elongated leaves in ferns, monocots and gymnosperms tended to have highly elongated cells. Our results reveal the diversity of pavement cell shapes, and lays the quantitative groundwork for testing hypotheses about pavement cell form and function within a phylogenetic context.
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Affiliation(s)
- Róza V. Vőfély
- The Sainsbury LaboratoryUniversity of CambridgeBateman StreetCambridgeCB1 2LRUK
| | - Joseph Gallagher
- Department of BiologyUniversity of Massachusetts611 North Pleasant StreetAmherstMA01003‐9297USA
| | - Grace D. Pisano
- Department of BiologyUniversity of Massachusetts611 North Pleasant StreetAmherstMA01003‐9297USA
| | - Madelaine Bartlett
- Department of BiologyUniversity of Massachusetts611 North Pleasant StreetAmherstMA01003‐9297USA
| | - Siobhan A. Braybrook
- The Sainsbury LaboratoryUniversity of CambridgeBateman StreetCambridgeCB1 2LRUK
- Department of Molecular, Cell and Developmental BiologyUniversity of California at Los Angeles610 Charles E Young Dr. SouthLos AngelesCA90095USA
- Molecular Biology InstituteUniversity of California at Los Angeles611 Charles E. Young Drive EastLos AngelesCA90095‐1570USA
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40
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Calamari ZT, Kuang-Hsien Hu J, Klein OD. Tissue Mechanical Forces and Evolutionary Developmental Changes Act Through Space and Time to Shape Tooth Morphology and Function. Bioessays 2018; 40:e1800140. [PMID: 30387177 PMCID: PMC6516060 DOI: 10.1002/bies.201800140] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/06/2018] [Indexed: 12/24/2022]
Abstract
Efforts from diverse disciplines, including evolutionary studies and biomechanical experiments, have yielded new insights into the genetic, signaling, and mechanical control of tooth formation and functions. Evidence from fossils and non-model organisms has revealed that a common set of genes underlie tooth-forming potential of epithelia, and changes in signaling environments subsequently result in specialized dentitions, maintenance of dental stem cells, and other phenotypic adaptations. In addition to chemical signaling, tissue forces generated through epithelial contraction, differential growth, and skeletal constraints act in parallel to shape the tooth throughout development. Here recent advances in understanding dental development from these studies are reviewed and important gaps that can be filled through continued application of evolutionary and biomechanical approaches are discussed.
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Affiliation(s)
- Zachary T. Calamari
- Department of Natural Sciences, Baruch College, City University of New York, New York City, New York, 10010, USA
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, California, 94143, USA
| | - Jimmy Kuang-Hsien Hu
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, California, 94143, USA
| | - Ophir D. Klein
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, California, 94143, USA
- Department of Pediatrics and Institute for Human Genetics, University of California, San Francisco, San Francisco, California, 94143, USA
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41
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Croft DA. Evolution of teeth in South America. Science 2018; 362:533. [DOI: 10.1126/science.aav6745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Darin A. Croft
- Department of Anatomy, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4930, USA
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42
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Phytoliths indicate significant arboreal cover at Sahelanthropus type locality TM266 in northern Chad and a decrease in later sites. J Hum Evol 2018; 106:66-83. [PMID: 28434541 DOI: 10.1016/j.jhevol.2017.01.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 01/12/2017] [Accepted: 01/18/2017] [Indexed: 11/21/2022]
Abstract
We analyzed phytolith and diatom remains preserved at 45 Miocene and Pliocene localities dated between 8 and 1 Ma in northern Chad (16-17°N). Some of these localities yielded cranial remains, lower jaws, and teeth of the hominin species Australopithecus bahrelghazali (∼3.6 Ma) and Sahelanthropus tchadensis (∼7 Ma). Of the 111 sediment samples analyzed, 41 yielded phytoliths, 20 yielded diatoms, and seven yielded both phytoliths and diatoms. Freshwater planktonic and tychoplanktonic diatom species, indicative of lacustrine conditions, are dominant (>91%) in the samples. The phytolith assemblages indicate an opening of the vegetation and a general trend toward an expansion of grass-dominated environments during the time spanning the two hominin occurrences in Chad. The phytoliths suggest the presence of a mosaic environment, including closed forest patches, palm groves, and mixed/grassland formations, between 7.5 and 7 Ma, the replacement by palm grove-like vegetation at approximately 6.5-5 Ma, and the presence of exclusive grass-dominated formations after 4.5 Ma. The type-locality of S. tchadensis (TM266) was likely similar to modern palm grove formations with an arboreal cover percentage ≥40%. The type locality of A. bahrelghazali (KT12) was a grass-dominated ecosystem (likely savanna) with an unrated percentage of arboreal cover. Furthermore, the grass phytolith data support the existence of a (recurrent) Sahelian-like dry climate in northern Chad since at least 8 Ma. Therefore the local closed vegetation formations in the Djurab region at 7.5-7 Ma were sustained by aquatic systems (such as lakes or related rivers, marshes) rather than by extensive annual precipitation.
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Phytoliths in Paleoecology: Analytical Considerations, Current Use, and Future Directions. VERTEBRATE PALEOBIOLOGY AND PALEOANTHROPOLOGY 2018. [DOI: 10.1007/978-3-319-94265-0_12] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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44
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Gomes Rodrigues H, Cornette R, Clavel J, Cassini G, Bhullar BAS, Fernández-Monescillo M, Moreno K, Herrel A, Billet G. Differential influences of allometry, phylogeny and environment on the rostral shape diversity of extinct South American notoungulates. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171816. [PMID: 29410874 PMCID: PMC5792951 DOI: 10.1098/rsos.171816] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 12/21/2017] [Indexed: 05/15/2023]
Abstract
Understanding the mechanisms responsible for phenotypic diversification, and the associated underlying constraints and ecological factors represents a central issue in evolutionary biology. Mammals present a wide variety of sizes and shapes, and are characterized by a high number of morphological convergences that are hypothesized to reflect similar environmental pressures. Extinct South American notoungulates evolved in isolation from northern mammalian faunas in highly disparate environments. They present a wide array of skeletal phenotypes and convergences, such as ever-growing dentition. Here, we focused on the origins of the rostral diversity of notoungulates by quantifying the shape of 26 genera using three-dimensional geometric morphometric analysis. We tested the influence of allometry and phylogeny on rostral shape and evaluated rates of evolutionary change in the different clades. We found strong allometric and phylogenetic signals concerning the rostral shape of notoungulates. Despite convergent forms, we observed a diffuse diversification of rostral shape, with no significant evidence of influence by large-scaled environmental variation. This contrasts with the increase in dental crown height that occurred in four late-diverging families in response to similar environmental pressures. These results illustrate the importance of considering both biological components and evolutionary rates to better understand some aspects of phenotypic diversity.
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Affiliation(s)
- Helder Gomes Rodrigues
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), UMR CNRS 7207, CP38, Muséum National d'Histoire Naturelle, Univ Paris 6, 8 rue Buffon, 75005 Paris, France
- Mécanismes adaptatifs et évolution (MECADEV), UMR 7179, CNRS, Funevol team, Muséum National d'Histoire Naturelle, 55 rue Buffon, Bat. Anatomie Comparée, CP 55, 75005, Paris Cedex 5, France
- Author for correspondence: Helder Gomes Rodrigues e-mail:
| | - Raphaël Cornette
- Institut de Systématique, Evolution, Biodiversité (ISYEB UMR 7205), MNHN, CNRS, UPMC, CP26, Sorbonne Universités, 57 rue Cuvier, 75005 Paris, France
| | - Julien Clavel
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), CNRS UMR 8197, INSERM U1024, Ecole Normale Supérieure, Paris Sciences et Lettres (PSL), Research University, 75005 Paris, France
| | - Guillermo Cassini
- División Mastozoología, Museo Argentino de Ciencias Naturales ‘‘Bernardino Rivadavia’’(MACN), Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Ciencias Básicas, Universidad Nacional de Luján (UNLu), Luján, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Yale University, PO Box 208109, New Haven, CT 06520, USA
| | - Bhart-Anjan S. Bhullar
- Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, CT 06520, USA
- Peabody Museum of Natural History, Yale University, 170 Whitney Avenue, New Haven, CT 06511, USA
| | - Marcos Fernández-Monescillo
- Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT–CONICET–Mendoza, Avenida Ruiz Leal s/n, Parque Gral, San Martín 5500, Mendoza, Argentina
| | - Karen Moreno
- Instituto de Ciencias de la Tierra, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Anthony Herrel
- Mécanismes adaptatifs et évolution (MECADEV), UMR 7179, CNRS, Funevol team, Muséum National d'Histoire Naturelle, 55 rue Buffon, Bat. Anatomie Comparée, CP 55, 75005, Paris Cedex 5, France
| | - Guillaume Billet
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), UMR CNRS 7207, CP38, Muséum National d'Histoire Naturelle, Univ Paris 6, 8 rue Buffon, 75005 Paris, France
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45
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Gomes Rodrigues H, Lefebvre R, Fernández-Monescillo M, Mamani Quispe B, Billet G. Ontogenetic variations and structural adjustments in mammals evolving prolonged to continuous dental growth. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170494. [PMID: 28791172 PMCID: PMC5541567 DOI: 10.1098/rsos.170494] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/29/2017] [Indexed: 06/07/2023]
Abstract
Studying dental ontogeny in mammals can provide valuable insight on the evolution of their masticatory apparatus and their related adaptations. The multiple acquisitions of a prolonged to continuous growth of teeth in herbivorous mammals in response to high abrasion represent an intensively investigated issue. However, the ontogenetic and architectural patterns associated with these repeated dental innovations remain poorly known. Here, we focused on two case studies corresponding to distant mammalian clades, the extinct Mesotheriidae (Notoungulata), which shared some striking dental features with the extant Ctenodactylidae (Rodentia). We studied the impact of prolonged to continuous growth of molars on their occlusal complexity, their relative size and their dynamics in the jaw. We found that variations of occlusal complexity patterns are the result of paedomorphic or peramorphic heterochronic processes impacting dental crown. We showed that variations in both upper and lower molar proportions generally follow the inhibitory developmental cascade model. In that context, prolonged dental growth implies transitory adjustments due to wear, and also involves dental migration and loss when combined with molar lengthening. Interestingly, these features may be present in many mammals having prolonged dental growth, and emphasize the crucial need of considering these aspects in future evolutionary and developmental studies.
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Affiliation(s)
- Helder Gomes Rodrigues
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), UMR CNRS 7207, CP38, Muséum national d'Histoire naturelle, Univ Paris 6, 8 rue Buffon, 75005 Paris, France
- Mécanismes adaptatifs et évolution (MECADEV), UMR 7179, CNRS, Funevol team, Muséum National d'Histoire Naturelle, 55 rue Buffon, Bat. Anatomie Comparée, CP 55, 75005, Paris Cedex 5, France
| | - Rémi Lefebvre
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), UMR CNRS 7207, CP38, Muséum national d'Histoire naturelle, Univ Paris 6, 8 rue Buffon, 75005 Paris, France
| | - Marcos Fernández-Monescillo
- Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT–CONICET–Mendoza, Avda. Ruiz Leal s/n, Parque Gral, San Martín 5500, Mendoza, Argentina
| | - Bernardino Mamani Quispe
- Departamento de Paleontología, Museo Nacional de Historia Natural, Calle 26 s/n, Cota Cota, La Paz, Bolivia
| | - Guillaume Billet
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), UMR CNRS 7207, CP38, Muséum national d'Histoire naturelle, Univ Paris 6, 8 rue Buffon, 75005 Paris, France
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46
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Pound MJ, Salzmann U. Heterogeneity in global vegetation and terrestrial climate change during the late Eocene to early Oligocene transition. Sci Rep 2017; 7:43386. [PMID: 28233862 PMCID: PMC5324063 DOI: 10.1038/srep43386] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/20/2017] [Indexed: 11/29/2022] Open
Abstract
Rapid global cooling at the Eocene – Oligocene Transition (EOT), ~33.9–33.5 Ma, is widely considered to mark the onset of the modern icehouse world. A large and rapid drop in atmospheric pCO2 has been proposed as the driving force behind extinctions in the marine realm and glaciation on Antarctica. However, the global terrestrial response to this cooling is uncertain. Here we present the first global vegetation and terrestrial temperature reconstructions for the EOT. Using an extensive palynological dataset, that has been statistically grouped into palaeo-biomes, we show a more transitional nature of terrestrial climate change by indicating a spatial and temporal heterogeneity of vegetation change at the EOT in both hemispheres. The reconstructed terrestrial temperatures show for many regions a cooling that started well before the EOT and continued into the Early Oligocene. We conclude that the heterogeneous pattern of global vegetation change has been controlled by a combination of multiple forcings, such as tectonics, sea-level fall and long-term decline in greenhouse gas concentrations during the late Eocene to early Oligocene, and does not represent a single response to a rapid decline in atmospheric pCO2 at the EOT.
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Affiliation(s)
- Matthew J Pound
- Department of Geography, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK
| | - Ulrich Salzmann
- Department of Geography, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK
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47
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Gomes Rodrigues H, Herrel A, Billet G. Ontogenetic and life history trait changes associated with convergent ecological specializations in extinct ungulate mammals. Proc Natl Acad Sci U S A 2017; 114:1069-1074. [PMID: 28096389 PMCID: PMC5293108 DOI: 10.1073/pnas.1614029114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Investigating life history traits in mammals is crucial to understand their survival in changing environments. However, these parameters are hard to estimate in a macroevolutionary context. Here we show that the use of dental ontogenetic parameters can provide clues to better understand the adaptive nature of phenotypic traits in extinct species such as South American notoungulates. This recently extinct order of mammals evolved in a context of important geological, climatic, and environmental variations. Interestingly, notoungulates were mostly herbivorous and acquired high-crowned teeth very early in their evolutionary history. We focused on the variations in crown height, dental eruption pattern, and associated body mass of 69 notoungulate taxa, placed in their phylogenetic and geological contexts. We showed that notoungulates evolved higher crowns several times between 45 and 20 Ma, independently of the variation in body mass. Interestingly, the independent acquisitions of ever-growing teeth were systematically accompanied by eruption of molars faster than permanent premolars. These repeated associations of dental innovations have never been documented for other mammals and raise questions on their significance and causal relationships. We suggest that these correlated changes could originate from ontogenetic adjustments favored by structural constraints, and may indicate accelerated life histories. Complementarily, these more durable and efficient dentitions could be selected to cope with important ingestions of abrasive particles in the context of intensified volcanism and increasing aridity. This study demonstrates that assessing both life history and ecological traits allows a better knowledge of the specializations of extinct mammals that evolved under strong environmental constraints.
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Affiliation(s)
- Helder Gomes Rodrigues
- Sorbonne Universités, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, UMR CNRS 7207, CP 38, Muséum National d'Histoire Naturelle, 75005 Paris, France;
- Mécanismes Adaptatifs et Evolution, UMR CNRS 7179, Bâtiment Anatomie Comparée, CP 55, Muséum National d'Histoire Naturelle, 75005 Paris, France
| | - Anthony Herrel
- Mécanismes Adaptatifs et Evolution, UMR CNRS 7179, Bâtiment Anatomie Comparée, CP 55, Muséum National d'Histoire Naturelle, 75005 Paris, France
| | - Guillaume Billet
- Sorbonne Universités, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, UMR CNRS 7207, CP 38, Muséum National d'Histoire Naturelle, 75005 Paris, France
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48
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Merceron G, Ramdarshan A, Blondel C, Boisserie JR, Brunetiere N, Francisco A, Gautier D, Milhet X, Novello A, Pret D. Untangling the environmental from the dietary: dust does not matter. Proc Biol Sci 2016; 283:20161032. [PMID: 27629027 PMCID: PMC5031653 DOI: 10.1098/rspb.2016.1032] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/17/2016] [Indexed: 11/12/2022] Open
Abstract
Both dust and silica phytoliths have been shown to contribute to reducing tooth volume during chewing. However, the way and the extent to which they individually contribute to tooth wear in natural conditions is unknown. There is still debate as to whether dental microwear represents a dietary or an environmental signal, with far-reaching implications on evolutionary mechanisms that promote dental phenotypes, such as molar hypsodonty in ruminants, molar lengthening in suids or enamel thickening in human ancestors. By combining controlled-food trials simulating natural conditions and dental microwear textural analysis on sheep, we show that the presence of dust on food items does not overwhelm the dietary signal. Our dataset explores variations in dental microwear textures between ewes fed on dust-free and dust-laden grass or browse fodders. Browsing diets with a dust supplement simulating Harmattan windswept environments contain more silica than dust-free grazing diets. Yet browsers given a dust supplement differ from dust-free grazers. Regardless of the presence or the absence of dust, sheep with different diets yield significantly different dental microwear textures. Dust appears a less significant determinant of dental microwear signatures than the intrinsic properties of ingested foods, implying that diet plays a critical role in driving the natural selection of dental innovations.
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Affiliation(s)
- Gildas Merceron
- Institut de Paléoprimatologie et Paléontologie Humaine: Evolution et Paléoenvironnements UMR 7262, CNRS and Université de Poitiers, 86073 Poitiers Cedex 9, France
| | - Anusha Ramdarshan
- Institut de Paléoprimatologie et Paléontologie Humaine: Evolution et Paléoenvironnements UMR 7262, CNRS and Université de Poitiers, 86073 Poitiers Cedex 9, France
| | - Cécile Blondel
- Institut de Paléoprimatologie et Paléontologie Humaine: Evolution et Paléoenvironnements UMR 7262, CNRS and Université de Poitiers, 86073 Poitiers Cedex 9, France
| | - Jean-Renaud Boisserie
- Institut de Paléoprimatologie et Paléontologie Humaine: Evolution et Paléoenvironnements UMR 7262, CNRS and Université de Poitiers, 86073 Poitiers Cedex 9, France Centre Français des Études Éthiopiennes USR 3137, CNRS and Ministère des Affaires Étrangères, Ambassade de France en Ethiopie, PO Box 5554, Addis Ababa, Ethiopia
| | - Noël Brunetiere
- Institut Pprime UPR 3346, CNRS, ENSMA and Université de Poitiers, 86962 Futuroscope Chasseneuil Cedex, France
| | - Arthur Francisco
- Institut Pprime UPR 3346, CNRS, ENSMA and Université de Poitiers, 86962 Futuroscope Chasseneuil Cedex, France
| | - Denis Gautier
- Ferme Expérimentale du Mourier, Institut de l'Elevage, 87800 St Priest Ligoure, France Centre Interrégional d'Information et de Recherche en Production Ovine, Ferme Expérimentale du Mourier, 87800 St Priest Ligoure, France
| | - Xavier Milhet
- Institut Pprime UPR 3346, CNRS, ENSMA and Université de Poitiers, 86962 Futuroscope Chasseneuil Cedex, France
| | - Alice Novello
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - Dimitri Pret
- IC2MP UMR 7285, CNRS and Université de Poitiers, 86073 Poitiers Cedex 9, France
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Strömberg CAE, Di Stilio VS, Song Z. Functions of phytoliths in vascular plants: an evolutionary perspective. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12692] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Caroline A. E. Strömberg
- Department of Biology University of Washington Seattle WA 98195 USA
- Burke Museum of Natural History & Culture University of Washington Seattle WA 98195 USA
| | | | - Zhaoliang Song
- Department of Biology University of Washington Seattle WA 98195 USA
- Institute of the Surface‐Earth System Science Research Tianjin University Tianjin 300072 China
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50
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Urban MA, Barclay RS, Sivaguru M, Punyasena SW. Cuticle and subsurface ornamentation of intact plant leaf epidermis under confocal and superresolution microscopy. Microsc Res Tech 2016; 81:129-140. [PMID: 27111826 DOI: 10.1002/jemt.22667] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/15/2016] [Accepted: 03/19/2016] [Indexed: 11/07/2022]
Abstract
Plant cuticle micromorphology is an invaluable tool in modern ecology and paleoecology. It has expanded our knowledge of systematic relationships among diverse plant groups and can be used to identify fossil plants. Furthermore, fossil plant leaf micromorphology is used for reconstructing past environments, most notably for estimating atmospheric CO2 concentration. Here we outline a new protocol for imaging plant cuticle for archival and paleoecological applications. Traditionally, both modern reference and fossil samples undergo maceration with subsequent imaging via environmental SEM, widefield fluorescence, or light microscopy. In this paper, we demonstrate the capabilities of alternative preparation and imaging methods using confocal and superresolution microscopy with intact leaf samples. This method produces detailed three-dimensional images of surficial and subsurface structures of the intact leaf. Multiple layers are captured simultaneously, which previously required independent maceration and microtome steps. We compared clearing agents (chloral hydrate, KOH, and Visikol); mounting media (Eukitt and Hoyer's); fluorescent stains (periodic acid Schiff, propidium iodide); and confocal vs. superresolution microscopes. We conclude that Eukitt is the best medium for long-term preservation and imaging. Because of nontoxicity and ease of procurement, Visikol made for the best clearing agent. Staining improves contrast and under most circumstances PAS provided the clearest images. Supperresolution produced higher clarity images than traditional confocal, but the information gained was minimal. This new protocol provides the botanical and paleobotanical community an alternative to traditional techniques. Our proposed workflow has the net benefit of being more efficient than traditional methods, which only capture the surface of the plant epidermis. Microsc. Res. Tech. 81:129-140, 2018. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Michael A Urban
- Department of Plant Biology, University of Illinois, 505 South Goodwin Avenue, Urbana, Illinois, 61801
| | - Richard S Barclay
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, 10th and Constitution Avenue NW, Washington, DC, 20560
| | - Mayandi Sivaguru
- Institute for Genomic Biology, University of Illinois, 1206 West Gregory Drive, Urbana, Illinois, 61801
| | - Surangi W Punyasena
- Department of Plant Biology, University of Illinois, 505 South Goodwin Avenue, Urbana, Illinois, 61801
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