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Heo N, Leopold DJ, Lomolino MV, Yun S, Fernando DD. Global and regional drivers of abundance patterns in the hart's tongue fern complex (Aspleniaceae). ANNALS OF BOTANY 2023; 131:737-750. [PMID: 36273331 PMCID: PMC10184436 DOI: 10.1093/aob/mcac129] [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: 07/19/2022] [Revised: 10/06/2022] [Accepted: 10/21/2022] [Indexed: 05/16/2023]
Abstract
BACKGROUND AND AIMS The hart's tongue fern (HTF) complex is a monophyletic group composed of five geographically segregated members with divergent abundance patterns across its broad geographic range. We postulated hierarchical systems of environmental controls in which climatic and land-use change drive abundance patterns at the global scale, while various ecological conditions function as finer scale determinants that further increase geographic disparities at regional to local scales. METHODS After quantifying the abundance patterns of the HTF complex, we estimated their correlations with global climate and land-use dynamics. Regional determinants were assessed using boosted regression tree models with 18 potential ecological variables. Moreover, we investigated long-term population trends in the USA to understand the interplay of climate change and anthropogenic activities on a temporal scale. KEY RESULTS Latitudinal climate shifts drove latitudinal abundance gradients, and regionally different levels of land-use change resulted in global geographic disparities in population abundance. At a regional scale, population isolation, which accounts for rescue effects, played an important role, particularly in Europe and East Asia where several hot spots occurred. Furthermore, the variables most strongly influencing abundance patterns greatly differed by region: precipitation seasonality in Europe; spatial heterogeneity of temperature and precipitation in East Asia; and magnitudes of past climate change, temperature seasonality and edaphic conditions in North America. In the USA, protected populations showed increasing trends compared with unprotected populations at the same latitude, highlighting the critical role of habitat protection in conservation measures. CONCLUSIONS Geographic disparities in the abundance patterns of the HTF complex were determined by hierarchical systems of environmental controls, wherein climatic and land-use dynamics act globally but are modulated by various regional and local determinants operating at increasingly finer scales. We highlighted that fern conservation must be tailored to particular geographic contexts and environmental conditions by incorporating a better understanding of the dynamics acting at different spatiotemporal scales.
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Affiliation(s)
- Namjoo Heo
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210, USA
| | - Donald J Leopold
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210, USA
| | - Mark V Lomolino
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210, USA
| | - Seona Yun
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210, USA
| | - Danilo D Fernando
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210, USA
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Heo N, Lomolino MV, Watkins JE, Yun S, Weber-Townsend J, Fernando DD. Evolutionary history of the Asplenium scolopendrium complex (Aspleniaceae), a relictual fern with a northern pan-temperate disjunct distribution. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Asplenium scolopendrium is distributed in northern temperate forests with many global biogeographic disjunctions. The species complex of A. scolopendrium has been generated by spatial segregation coupled with divergent evolution. We elucidated the biogeographic history of the A. scolopendrium complex by exploring its origin, dispersal and evolution, thus providing insights into the evolutionary history of the Tertiary floras with northern pan-temperate disjunct distributions. The results revealed that all infraspecific taxa descended from a widely distributed common ancestor in the Northern Hemisphere. This pan-temperate ancestral population formed by unidirectional westward dispersal from European origins primarily during the Early Eocene when the Earth’s climate was much warmer than today. The splitting of European, American and East Asian lineages occurred during the Early Miocene due to geo-climatic vicariances. Polyploidy events in the American ancestral populations created additional reproductive barriers. The star-shaped haplotypes in each continent indicated that local disjunctions also led to derived genotypes with potential to diverge into different taxa. This intracontinental lineage splitting is likely related to latitudinal range shift and habitat fragmentation caused by glacial cycles and climate change during the Pleistocene. The evolutionary history of the A. scolopendrium complex supported the Boreotropical hypothesis exhibiting range expansion during the Early Eocene Climatic Optimum.
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Affiliation(s)
- Namjoo Heo
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry , 1 Forestry Drive, Syracuse, NY 13210 , USA
| | - Mark V Lomolino
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry , 1 Forestry Drive, Syracuse, NY 13210 , USA
| | - James E Watkins
- Department of Biology, Colgate University , 13 Oak Drive, Hamilton, NY 13346 , USA
| | - Seona Yun
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry , 1 Forestry Drive, Syracuse, NY 13210 , USA
| | - Josh Weber-Townsend
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry , 1 Forestry Drive, Syracuse, NY 13210 , USA
| | - Danilo D Fernando
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry , 1 Forestry Drive, Syracuse, NY 13210 , USA
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Hornych O, Černochová L, Lisner A, Ekrt L. An experimental assessment of competitive interactions between sexual and apomictic fern gametophytes using Easy Leaf Area. APPLICATIONS IN PLANT SCIENCES 2022; 10:e11466. [PMID: 35495190 PMCID: PMC9039791 DOI: 10.1002/aps3.11466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 01/25/2022] [Accepted: 01/31/2022] [Indexed: 05/14/2023]
Abstract
PREMISE Few studies have explored competition in fern gametophyte populations. One limiting factor is the tedious measurement of gametophyte size as a proxy for biomass in these small plants. Here, an alternative approach of estimating the number of green pixels from photos was employed to measure the competitive interactions among apomictic and sexual Dryopteris gametophytes. METHODS We cultivated the gametophytes of two apomictic (diploid and triploid) and one sexual (tetraploid) Dryopteris species in monocultures and in two-species mixtures in the ratios 1 : 1 and 1 : 3. The total gametophyte cover of each population originating from 20 spores was assessed using Easy Leaf Area. Assessments were performed weekly between weeks 4 and 10 of cultivation. Additionally, during week 5, the cover of each species in each mixture was estimated separately. RESULTS We identified a positive correlation between gametophyte size and ploidy level as well as sexual reproduction. The performance of the tested species in mixtures was dependent on the competitor species identity, indicating the importance of competition between gametophytes. DISCUSSION The methods outlined can be used for a rapid assessment of fern gametophyte cover in large gametophyte populations. Ploidy level and reproduction type seem to play a major role in the competitive abilities of fern gametophytes, but more research is needed on this topic.
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Affiliation(s)
- Ondřej Hornych
- Department of Botany, Faculty of ScienceUniversity of South BohemiaBranišovská 1760, České Budějovice, CZ‐37005Czech Republic
| | - Lucie Černochová
- Department of Botany, Faculty of ScienceUniversity of South BohemiaBranišovská 1760, České Budějovice, CZ‐37005Czech Republic
| | - Aleš Lisner
- Department of Botany, Faculty of ScienceUniversity of South BohemiaBranišovská 1760, České Budějovice, CZ‐37005Czech Republic
| | - Libor Ekrt
- Department of Botany, Faculty of ScienceUniversity of South BohemiaBranišovská 1760, České Budějovice, CZ‐37005Czech Republic
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Krieg CP, Chambers SM. The ecology and physiology of fern gametophytes: A methodological synthesis. APPLICATIONS IN PLANT SCIENCES 2022; 10:e11464. [PMID: 35495196 PMCID: PMC9039797 DOI: 10.1002/aps3.11464] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 12/21/2021] [Accepted: 01/10/2022] [Indexed: 05/14/2023]
Abstract
All green plants alternate between the gametophyte and sporophyte life stages, but only seed-free vascular plants (ferns and lycophytes) have independent, free-living gametophytes. Fern and lycophyte gametophytes are significantly reduced in size and morphological complexity relative to their sporophytic counterparts and have often been overlooked in ecological and physiological studies. Understanding the ecological and physiological factors that directly impact this life stage is of critical importance because the ultimate existence of a sporophyte is dependent upon successful fertilization in the gametophyte generation. Furthermore, previous research has shown that the dual nature of the life cycle and the high dispersibility of spores can result in different geographic patterns between gametophytes and their respective sporophytes. This variation in distribution patterns likely exacerbates the separation of selective pressures acting on gametophyte and sporophyte generations, and can uniquely impact a species' ecology and physiology. Here, we provide a review of historical and contemporary methodologies used to examine ecological and physiological aspects of fern gametophytes, as well as those that allow for comparisons between the two generations. We conclude by suggesting methodological approaches to answer currently outstanding questions. We hope that the information covered herein will serve as a guide to current researchers and stimulate future discoveries in fern gametophyte ecology and physiology.
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Affiliation(s)
| | - Sally M. Chambers
- Department of BotanyMarie Selby Botanical GardensSarasotaFlorida34236USA
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Nitta JH, Watkins JE, Holbrook NM, Wang TW, Davis CC. Ecophysiological differentiation between life stages in filmy ferns (Hymenophyllaceae). JOURNAL OF PLANT RESEARCH 2021; 134:971-988. [PMID: 34117960 DOI: 10.1007/s10265-021-01318-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 06/03/2021] [Indexed: 06/12/2023]
Abstract
Desiccation tolerance was a key trait that allowed plants to colonize land. However, little is known about the transition from desiccation tolerant non-vascular plants to desiccation sensitive vascular ones. Filmy ferns (Hymenophyllaceae) represent a useful system to investigate how water-stress strategies differ between non-vascular and vascular stages within a single organism because they have vascularized sporophytes and nonvascular gametophytes that are each capable of varying degrees of desiccation tolerance. To explore this, we surveyed sporophytes and gametophytes of 19 species (22 taxa including varieties) of filmy ferns on Moorea (French Polynesia) and used chlorophyll fluorescence to measure desiccation tolerance and light responses. We conducted phylogenetically informed analyses to identify differences in physiology between life stages and growth habits. Gametophytes had similar or less desiccation tolerance (ability to recover from 2 days desiccation at - 86 MPa) and lower photosynthetic optima (maximum electron transport rate of photosystem II and light level at 95% of that rate) than sporophytes. Epiphytes were more tolerant of desiccation than terrestrial species in both life stages. Despite their lack of greater physiological tolerances, gametophytes of several species occurred over a wider elevational range than conspecific sporophytes. Our results demonstrate that filmy fern gametophytes and sporophytes differ in their physiology and niche requirements, and point to the importance of microhabitat in shaping the evolution of water-use strategies in vascular plants.
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Affiliation(s)
- Joel H Nitta
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA.
- Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA, 02138, USA.
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
| | - James E Watkins
- Department of Biology, Colgate University, 13 Oak Drive, Hamilton, NY, 13346, USA
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Tristan W Wang
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA, 02138, USA
- Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Charles C Davis
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA, 02138, USA
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Grašič M, Sovdat T, Gaberščik A. Frond Optical Properties of the Fern Phyllitis scolopendrium Depend on Light Conditions in the Habitat. PLANTS 2020; 9:plants9101254. [PMID: 32977666 PMCID: PMC7598650 DOI: 10.3390/plants9101254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/15/2020] [Accepted: 09/22/2020] [Indexed: 12/11/2022]
Abstract
Ferns display an elevated degree of phenotypic plasticity to changes in irradiance levels; however, only a few reports deal with their response to different light conditions. To get an insight into the extent of phenotypic plasticity of the fern Phyllitis scolopendrium, thriving in a forested area along a radiation gradient at the entrance of a cave, we examined selected biochemical, morphological, and physiological frond traits of the ferns from three different habitats. Sampling was performed two times during the vegetation season, in April and June. We also measured frond optical properties to point out the differences in leaf/light interactions between different plant samples. According to frond size, the middle habitat, receiving 125 µmol m−2s−1 of photosynthetically active radiation at both sampling times, appeared to be the most favourable. The production of UV-absorbing substances was highest in the habitat with the lowest radiation level. At the beginning of the season, the level of photosynthetic pigments in this habitat was the same as in the other habitats, while it was significantly lower in June when the tree canopy was closed. Frond reflectance was similar when comparing habitats and different sampling times. The most significant differences were obtained in the UV-A and near-infrared regions. The reflectance spectra depended mainly on frond biochemical properties, which altogether explained 54% (p ≤ 0.05) of the spectra variability. Frond transmittance depended on both, morphological parameters, explaining 51% (p ≤ 0.05), and frond biochemistry, explaining 73% (p ≤ 0.05) of the spectra variability. P. scolopendrium was revealed to be highly plastic regarding light conditions. The shapes of the frond reflectance and transmittance optical curves were similar to those typical of leaves of seed plants. The fronds exhibited high morphological plasticity when comparing different habitats. However, their biochemical and optical traits differed more between the two sampling times than between the habitats.
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Gabriel y Galán JM, Murciano A, Sirvent L, Sánchez A, Watkins JE. Germination fitness of two temperate epiphytic ferns shifts under increasing temperatures and forest fragmentation. PLoS One 2018; 13:e0197110. [PMID: 29750811 PMCID: PMC5947888 DOI: 10.1371/journal.pone.0197110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/26/2018] [Indexed: 11/18/2022] Open
Abstract
Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates. A mathematical model was developed for two temperate epiphytic ferns in order to predict potential impacts on spore germination kinetics, in response to different scenarios of global change, coming from increasing temperature and forest fragmentation. Our results show that an increasing temperature will have a negative impact over the populations of these temperate epiphytic ferns. Under unfragmented forests the germination percentage was comparatively less influenced than in fragmented patches. This study highlight that, in the long term, populations of the studied epiphytic temperate ferns may decline due to climate change. Overall, epiphytic fern communities will suffer changes in diversity, richness and dominance. Our study draws attention to the role of ferns in epiphytic communities of temperate forests, emphasizing the importance of considering these plants in any conservation strategy, specifically forest conservation. From a methodological point of view, the model we propose could be easily used to dynamically monitor the status of ecosystems, allowing the quick prediction of possible future scenarios, which is a crucial issue in biodiversity conservation decision-making.
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Affiliation(s)
- Jose María Gabriel y Galán
- Unit of Botany, Department of Biodiversity, Ecology and Evolution, Faculty of Biology, Universidad Complutense, Madrid, Spain
| | - Antonio Murciano
- “Neural Plasticity Research Group, IdISSC”, Unit of Biomathematics, Department of Biodiversity, Ecology and Evolution, Faculty of Biology, Universidad Complutense, Madrid, Spain
- “Neuro-computing and Neuro-robotics Research Group, UCM”, Unit of Biomathematics, Department of Biodiversity, Ecology and Evolution, Faculty of Biology, Universidad Complutense, Madrid, Spain
| | | | - Abel Sánchez
- “Neural Plasticity Research Group, IdISSC”, Unit of Biomathematics, Department of Biodiversity, Ecology and Evolution, Faculty of Biology, Universidad Complutense, Madrid, Spain
- “Neuro-computing and Neuro-robotics Research Group, UCM”, Unit of Biomathematics, Department of Biodiversity, Ecology and Evolution, Faculty of Biology, Universidad Complutense, Madrid, Spain
| | - James E. Watkins
- Department of Biology, Colgate University, Hamilton, New York, United States of America
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Testo WL, Sundue MA. Are rates of species diversification and body size evolution coupled in the ferns? AMERICAN JOURNAL OF BOTANY 2018; 105:525-535. [PMID: 29637539 DOI: 10.1002/ajb2.1044] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 11/09/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Understanding the relationship between phenotypic evolution and lineage diversification is a central goal of evolutionary biology. To extend our understanding of the role morphological evolution plays in the diversification of plants, we examined the relationship between leaf size evolution and lineage diversification across ferns. METHODS We tested for an association between body size evolution and lineage diversification using a comparative phylogenetic approach that combined a time-calibrated phylogeny and leaf size data set for 2654 fern species. Rates of leaf size change and lineage diversification were estimated using BAMM, and rate correlations were performed for rates obtained for all families and individual species. Rates and patterns of rate-rate correlation were also analyzed separately for terrestrial and epiphytic taxa. KEY RESULTS We find no significant correlation between rates of leaf area change and lineage diversification, nor was there a difference in this pattern when growth habit is considered. Our results are consistent with the findings of an earlier study that reported decoupled rates of body size evolution and diversification in the Polypodiaceae, but conflict with a recent study that reported a positive correlation between body size evolution and lineage diversification rates in the tree fern family Cyatheaceae. CONCLUSIONS Our findings indicate that lineage diversification in ferns is largely decoupled from shifts in body size, in contrast to several other groups of organisms. Speciation in ferns appears to be primarily driven by hybridization and isolation along elevational gradients, rather than adaptive radiations featuring prominent morphological restructuring. The exceptional diversity of leaf morphologies in ferns appears to reflect a combination of ecophysiological constraints and adaptations that are not key innovations.
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Affiliation(s)
- Weston L Testo
- The Pringle Herbarium, University of Vermont, 27 Colchester Drive, Burlington, VT, 05405, USA
| | - Michael A Sundue
- The Pringle Herbarium, University of Vermont, 27 Colchester Drive, Burlington, VT, 05405, USA
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Haufler CH, Pryer KM, Schuettpelz E, Sessa EB, Farrar DR, Moran R, Schneller JJ, Watkins JE, Windham MD. Sex and the Single Gametophyte: Revising the Homosporous Vascular Plant Life Cycle in Light of Contemporary Research. Bioscience 2016. [DOI: 10.1093/biosci/biw108] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Sessa EB, Testo WL, Watkins JE. On the widespread capacity for, and functional significance of, extreme inbreeding in ferns. THE NEW PHYTOLOGIST 2016; 211:1108-1119. [PMID: 27094807 DOI: 10.1111/nph.13985] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/18/2016] [Indexed: 06/05/2023]
Abstract
Homosporous vascular plants utilize three different mating systems, one of which, gametophytic selfing, is an extreme form of inbreeding only possible in homosporous groups. This mating system results in complete homozygosity in all progeny and has important evolutionary and ecological implications. Ferns are the largest group of homosporous land plants, and the significance of extreme inbreeding for fern evolution has been a subject of debate for decades. We cultured gametophytes in the laboratory and quantified the relative frequencies of sporophyte production from isolated and paired gametophytes, and examined associations between breeding systems and several ecological and evolutionary traits. The majority of fern species studied show a capacity for gametophytic selfing, producing sporophytes from both isolated and paired gametophytes. While we did not follow sporophytes to maturity to investigate potential detrimental effects of homozygosity at later developmental stages, our results suggest that gametophytic selfing may have greater significance for fern evolution and diversification than has previously been realized. We present evidence from the largest study of mating behavior in ferns to date that the capacity for extreme inbreeding is prevalent in this lineage, and we discuss its implications and relevance and make recommendations for future studies of fern mating systems.
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Affiliation(s)
- Emily B Sessa
- Department of Biology, University of Florida, Box 118525, Gainesville, FL 32611, USA
| | - Weston L Testo
- Department of Plant Biology, University of Vermont, 111 Jeffords Hall, 63 Carrigan Drive, Burlington, VT, 05405, USA
| | - James E Watkins
- Biology Department, Colgate University, 129 Ho Science Center, 13 Oak Drive, Hamilton, NY, 13346, USA
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Chambers SM, Emery NC. Population differentiation and countergradient variation throughout the geographic range in the fern gametophyte Vittaria appalachiana. AMERICAN JOURNAL OF BOTANY 2016; 103:86-98. [PMID: 26758887 DOI: 10.3732/ajb.1500077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/29/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Theory predicts that limited gene flow between populations will promote population differentiation, and experimental studies have found that differentiation is often explained by local adaptation in sexually reproducing angiosperms. However, few experiments have examined the drivers of differentiation among populations in asexual land plants with limited dispersal potential. Here, we evaluated the role of temperature in driving population differentiation in an asexual, obligate gametophyte fern species. METHODS We reciprocally transplanted Vittaria appalachiana gametophytes among six populations that spanned the species' geographic range in the Appalachian Mountains and Plateau. Temperature, survival, and senescence rates were measured for 1 year. KEY RESULTS Populations had significantly different fitness responses to different sites, consistent with the hypothesis that populations have differentiated across the species' range. There was some evidence for local adaptation in marginal populations and for countergradient selection favoring particularly robust genotypes at the northern range edge. Most populations had relatively high fitness at the site with the most stable temperature conditions and were negatively affected by decreasing minimum temperatures. CONCLUSIONS Populations of Vittaria appalachiana exhibit highly variable responses to transplantation across the species' range, and only a small subset of these responses are due to local adaptation. Differences in daily minimum temperature explain some variation in fitness, but other site-specific factors also have significant impacts on transplant fitness. These results indicate that asexual, patchily distributed species with limited dispersal may exhibit population-specific responses to global climate change that have not been elucidated by empirical work focused on sexually reproducing angiosperms.
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Affiliation(s)
- Sally M Chambers
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA, 47907
| | - Nancy C Emery
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA, 47907 Department of Ecology and Evolutionary Biology, UCB 334, University of Colorado, Boulder, Colorado, 80309-0334 USA
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Riaño K, Briones O. Sensitivity of three tree ferns during their first phase of life to the variation of solar radiation and water availability in a Mexican cloud forest. AMERICAN JOURNAL OF BOTANY 2015; 102:1472-1481. [PMID: 26373979 DOI: 10.3732/ajb.1500228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 08/03/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Regeneration niche differentiation promotes species coexistence and diversity; however, the ecological implications for the initial life phases of the majority of pteridophytes are unknown. We analyzed the sensitivity of gametophytes and juvenile sporophytes of the tree ferns Alsophila firma, Cyathea divergens, and Lophosoria quadripinnata to variation in light and water availability. METHODS We evaluated gametophyte desiccation tolerance using saturated salt solutions and gametophyte solar radiation tolerance by direct exposure. We also transplanted juvenile sporophytes in environments with 7% and 23% canopy openness and two watering levels. KEY RESULTS The response of photosynthetic efficiency and water content suggest that the gametophytes of the three species require high relative humidity, tolerate direct solar radiation for up to 30 min and that the response is not species-dependent. Sporophyte size and gas exchange were greater in the more open site, but decreased watering had a lesser effect on these variables in the more closed site. Relative growth rate correlated with the net assimilation rate and leaf weight ratio. Juvenile sporophytes of A. firma were more shade tolerant, while those of C. divergens and L. quadripinnata acclimatized to both environments. CONCLUSIONS Specialization to humid habitats in the tree fern gametophyte restricts the species to humid forests, while differences in the plasticity of the sporophyte facilitate coexistence of the species.
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Affiliation(s)
- Karolina Riaño
- Instituto de Ecología, A.C., Carretera antigua a Coatepec 351, El Haya, Xalapa 91070 Veracruz, México
| | - Oscar Briones
- Instituto de Ecología, A.C., Carretera antigua a Coatepec 351, El Haya, Xalapa 91070 Veracruz, México
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Testo WL, Watkins JE, Barrington DS. Dynamics of asymmetrical hybridization in North American wood ferns: reconciling patterns of inheritance with gametophyte reproductive biology. THE NEW PHYTOLOGIST 2015; 206:785-795. [PMID: 25443156 DOI: 10.1111/nph.13213] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 11/11/2014] [Indexed: 06/04/2023]
Abstract
Hybridization is an important evolutionary force in plants, but the mechanisms underlying it have not been well studied for many groups. In particular, the drivers of non-random patterns of interspecific gene flow (asymmetrical hybridization) remain poorly understood, especially in the seed-free vascular plants. Here, we examine patterns of asymmetrical hybridization in two widespread fern hybrids from eastern North America and study the role of gametophyte ecology in the determination of hybridization bias. We characterized the maternal parentage of > 140 hybrid sporophytes by sequencing a c. 350-bp region of chloroplast DNA (cpDNA). To identify factors contributing to patterns of asymmetrical hybridization, we cultured gametophytes of the parental species and evaluated critical aspects of their reproductive biology. We found that asymmetrical hybridization was prevalent across the populations of both hybrids. Reproductive traits varied across species and suggest that selfing potential, antheridiogen responsiveness, sperm dispersal capacity and gamete size all contribute to the mediation of the direction of hybridization in this group. Our findings suggest that asymmetrical hybridization in ferns is driven by an array of reproductive traits. This study helps to sharpen and define a mechanistic understanding of patterns of hybridization in this group and demonstrates the importance of considering gametophyte biology when studying evolutionary processes in ferns.
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Affiliation(s)
- Weston L Testo
- Department of Plant Biology, University of Vermont, 111 Jeffords Hall, 63 Carrigan Drive, Burlington, VT, 05405, USA
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Stevens SM, Emery NC. Dispersal limitation and population differentiation in performance beyond a northern range limit in an asexually reproducing fern. DIVERS DISTRIB 2015. [DOI: 10.1111/ddi.12323] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Sally M. Stevens
- Department of Botany and Plant Pathology; 915 W State Street West Lafayette IN 47907-2054 USA
| | - Nancy C. Emery
- Departments of Biological Sciences and Botany and Plant Pathology; Purdue University; West Lafayette IN 47907-2054 USA
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