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Schaub EP, Mulder CPH, Diggle PK. Preforming floral primordia converge on a narrow range of stages at dormancy despite multiple effects of temperature on development. New Phytol 2022; 233:2599-2613. [PMID: 34510459 DOI: 10.1111/nph.17721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Abstract
Phenological studies often focus on relationships between flowering date and temperature or other environmental variables. Yet in species that preform flowers, anthesis is one stage of a lengthy developmental process, and effects of temperature on flower development in the year(s) before flowering are largely unknown. We investigated the effects of temperature during preformation on flower development in Vaccinium vitis-idaea. Using scanning electron microscopy, we established scores for developing primordia and examined effects of air temperature, depth of soil thaw, time of year and previous stage on development. Onset of flower initiation depends on soil thaw, and developmental change is greatest at early stages and during the warmest months. Regardless of temperature and time during the season, all basal floral primordia pause development at the same stage before whole-plant dormancy. Once primordia are initiated, development does not appear to be influenced by air temperature differences within the range of variation among our sites. There may be strong endogenous flower-level controls over development, particularly the stage at which morphogenesis ceases before dormancy. However, the strength of such internal controls in the face of continuing temperature extremes under a changing climate is unclear.
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Affiliation(s)
- Eileen P Schaub
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06268, USA
| | - Christa P H Mulder
- Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Pamela K Diggle
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06268, USA
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2
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McDermott MT, Doak P, Handel CM, Breed GA, Mulder CPH. Willow drives changes in arthropod communities of northwestern Alaska: ecological implications of shrub expansion. Ecosphere 2021. [DOI: 10.1002/ecs2.3514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Molly T. McDermott
- Department of Biology and Wildlife Institute of Arctic Biology University of Alaska Fairbanks Alaska99775USA
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage Alaska99508USA
| | - Patricia Doak
- Department of Biology and Wildlife Institute of Arctic Biology University of Alaska Fairbanks Alaska99775USA
| | - Colleen M. Handel
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage Alaska99508USA
| | - Greg A. Breed
- Department of Biology and Wildlife Institute of Arctic Biology University of Alaska Fairbanks Alaska99775USA
| | - Christa P. H. Mulder
- Department of Biology and Wildlife Institute of Arctic Biology University of Alaska Fairbanks Alaska99775USA
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Okano K, Bret‐Harte MS, Mulder CPH, Juday GP. Resource availability drives plant–plant interactions of conifer seedlings across elevations under warming in Alaska. Ecosphere 2021. [DOI: 10.1002/ecs2.3508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Kyoko Okano
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska99775USA
- Department of Biology and Wildlife University of Alaska Fairbanks Fairbanks Alaska99775USA
- Department of Biological Sciences Northern Arizona University Flagstaff Arizona86011USA
| | - M. Syndonia Bret‐Harte
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska99775USA
- Department of Biology and Wildlife University of Alaska Fairbanks Fairbanks Alaska99775USA
| | - Christa P. H. Mulder
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska99775USA
- Department of Biology and Wildlife University of Alaska Fairbanks Fairbanks Alaska99775USA
| | - Glenn P. Juday
- School of Natural Resources and Extension University of Alaska Fairbanks Fairbanks Alaska99775USA
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Cameron MD, Joly K, Breed GA, Mulder CPH, Kielland K. Pronounced Fidelity and Selection for Average Conditions of Calving Area Suggestive of Spatial Memory in a Highly Migratory Ungulate. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.564567] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A distinguishing characteristic of many migratory animals is their annual return to distinct calving (birthing) areas in the spring, yet the navigational mechanisms employed during migration that result in this pattern are poorly understood. Effective conservation of these species requires reliable delineation of such areas, quantifying the factors that influence their selection, and understanding the underlying mechanisms resulting in use of calving areas. We used barren-ground caribou (Rangifer tarandus granti) as a study species and identified calving sites of the Western Arctic Herd in Alaska using GPS collar data from 2010–2017. We assessed variability in calving areas by comparing spatial delineations across all combinations of years. To understand calving area selection at a landscape scale, we performed a resource selection analysis comparing calving sites to available locations across the herd’s range and incorporated time-varying, remotely sensed metrics of vegetation quality and quantity. We found that whereas calving areas varied from year to year, this annual variation was centered on an area of recurring attraction consistent with previous studies covering the last six decades. Calving sites were characterized by high-quality forage at the average time of calving, but not peak calving that year, and by a narrow range of distinct physiographic factors. Each year, calving sites were located on areas of above-average conditions based on our predictive model. Our findings indicate that the pattern of spring migration for pregnant females was to migrate to areas that consistently provide high-quality forage when averaged across years, and then upon arriving at this calving ground, refine selection using their perception of annually varying conditions that are driven by environmental stochasticity. We suggest that the well-documented and widespread pattern of fidelity to calving grounds by caribou is supportive of a navigational mechanism based on spatial memory at a broad scale to optimize foraging and energy acquisition at a critical life-history stage. The extent to which migrants depend on memory to reach their spring destinations has implications for the adaptability of populations to changing climate and human impacts.
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Parkinson LV, Mulder CPH. Patterns of pollen and resource limitation of fruit production in Vaccinium uliginosum and V. vitis-idaea in Interior Alaska. PLoS One 2020; 15:e0224056. [PMID: 32813718 PMCID: PMC7446802 DOI: 10.1371/journal.pone.0224056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 07/21/2020] [Indexed: 11/18/2022] Open
Abstract
Many recent studies assessing fruit productivity of plants in the boreal forest focus on interannual variability across a forested region, rather than on environmental variability within the forest. Frequency and severity of wildfires in the boreal forest affect soil moisture, canopy, and community structure at the landscape level, all of which may influence overall fruit production at a site directly or indirectly. We evaluated how fruit production in two boreal shrubs, Vaccinium uliginosum (blueberry) and V. vitis-idaea (lingonberry), was explained by factors associated with resource availability (such as canopy cover and soil conditions) and pollen limitation (such as floral resources for pollinators and pollen deposition) across boreal forest sites of Interior Alaska in 2017. We classified our study sites into upland and lowland sites, which differed in elevation, soil moisture, and active layer. We found that resource and pollen limitation differed between the two species and between uplands and lowlands. Lingonberry was more pollen limited than blueberry, and plants in lowland sites were more pollen limited relative to other sites while plants in upland sites were relatively more resource limited. Additionally, canopy cover had a significant negative effect in upland sites on a ramet’s investment in reproductive tissues and leaves versus structural growth, but little effect in lowland sites. These results point to importance of including pollinator service as well as resource availability in predictions for changes in berry abundance.
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Affiliation(s)
- Lindsey Viann Parkinson
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska, United States of America
- * E-mail:
| | - Christa P. H. Mulder
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska, United States of America
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Diggle PK, Mulder CPH. Diverse Developmental Responses to Warming Temperatures Underlie Changes in Flowering Phenologies. Integr Comp Biol 2019; 59:559-570. [DOI: 10.1093/icb/icz076] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Climate change has resulted in increased temperature means across the globe. Many angiosperms flower earlier in response to rising temperature and the phenologies of these species are reasonably well predicted by models that account for spring (early growing season) and winter temperatures. Surprisingly, however, exceptions to the general pattern of precocious flowering are common. Many species either do not appear to respond or even delay flowering in, or following, warm growing seasons. Existing phenological models have not fully addressed such exceptions to the common association of advancing phenologies with warming temperatures. The phenological events that are typically recorded (e.g., onset of flowering) are but one phase in a complex developmental process that often begins one or more years previously, and flowering time may be strongly influenced by temperature over the entire multi-year course of flower development. We propose a series of models that explore effects of growing-season temperature increase on the multiple processes of flower development and how changes in development may impact the timing of anthesis. We focus on temperate forest trees, which are characterized by preformation, the initiation of flower primordia one or more years prior to anthesis. We then synthesize the literature on flower development to evaluate the models. Although fragmentary, the existing data suggest the potential for temperature to affect all aspects of flower development in woody perennials. But, even for relatively well studied taxa, the critical developmental responses that underlie phenological patterns are difficult to identify. Our proposed models explain the seemingly counter-intuitive observations that warmer growing-season temperatures delay flowering in many species. Future research might concentrate on taxa that do not appear to respond to temperature, or delay flowering in response to warm temperatures, to understand what processes contribute to this pattern.
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Affiliation(s)
- Pamela K Diggle
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Christa P H Mulder
- Department of Biology and Wildlife & Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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Thoresen JJ, Towns D, Leuzinger S, Durrett M, Mulder CPH, Wardle DA. Invasive rodents have multiple indirect effects on seabird island invertebrate food web structure. Ecol Appl 2017; 27:1190-1198. [PMID: 28140497 DOI: 10.1002/eap.1513] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 01/05/2017] [Accepted: 01/11/2017] [Indexed: 06/06/2023]
Abstract
Burrowing seabirds that nest on islands transfer nutrients from the sea, disturb the soil through burrowing, damage tree foliage when landing, and thereby modify the surface litter. However, seabirds are in decline worldwide, as are their community- and ecosystem-level impacts, primarily due to invasive predatory mammals. The direct and indirect effects of seabird decline on communities and ecosystems are inherently complex. Here we employed network analysis, as a means of simplifying ecological complexity, to better understand the effects seabird loss may have on island invertebrate communities. Using data on leaf litter communities, we constructed invertebrate food webs for each of 18 offshore oceanic islands in northeastern New Zealand, nine of which have high seabird densities and nine of were invaded by rats. Ten network topological metrics (including entropy, generality, and vulnerability) were compared between rat-invaded and uninvaded (seabird-dominant) islands. We found that, on rat-invaded islands, the invertebrate food webs were smaller and less complex than on their seabird-dominated counterparts, which may be due to the suppression of seabird-derived nutrients and consequent effects on trophic cascades. This decreased complexity of food webs due to the presence of rats is indicative of lower ecosystem resistance via lower trophic redundancy. Our results show that rat effects on island ecosystems are manifested throughout entire food webs, and demonstrate how network analysis may be useful to assess ecosystem recovery status as these invaded islands are restored.
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Affiliation(s)
- Joshua J Thoresen
- Institute for Applied Ecology, Auckland University of Technology, 33 Symonds Street, Auckland, New Zealand
| | - David Towns
- Institute for Applied Ecology, Auckland University of Technology, 33 Symonds Street, Auckland, New Zealand
- Department of Conservation, Private Bag 68-908, Auckland, New Zealand
| | - Sebastian Leuzinger
- Institute for Applied Ecology, Auckland University of Technology, 33 Symonds Street, Auckland, New Zealand
| | - Mel Durrett
- Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
- Department of Biology, Rhodes College, 2000 North Parkway, Memphis, Tennessee, 38112, USA
| | - Christa P H Mulder
- Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
| | - David A Wardle
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE901-83, Umeå, Sweden
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8
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Mulder CPH, Iles DT, Rockwell RF. Increased variance in temperature and lag effects alter phenological responses to rapid warming in a subarctic plant community. Glob Chang Biol 2017; 23:801-814. [PMID: 27273120 DOI: 10.1111/gcb.13386] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 05/17/2016] [Accepted: 05/27/2016] [Indexed: 06/06/2023]
Abstract
Summer temperature on the Cape Churchill Peninsula (Manitoba, Canada) has increased rapidly over the past 75 years, and flowering phenology of the plant community is advanced in years with warmer temperatures (higher cumulative growing degree days). Despite this, there has been no overall shift in flowering phenology over this period. However, climate change has also resulted in increased interannual variation in temperature; if relationships between phenology and temperature are not linear, an increase in temperature variance may interact with an increase in the mean to alter how community phenology changes over time. In our system, the relationship between phenology and temperature was log-linear, resulting in a steeper slope at the cold end of the temperature spectrum than at the warm end. Because below-average temperatures had a greater impact on phenology than above-average temperatures, the long-term advance in phenology was reduced. In addition, flowering phenology in a given year was delayed if summer temperatures were high the previous year or 2 years earlier (lag effects), further reducing the expected advance over time. Phenology of early-flowering plants was negatively affected only by temperatures in the previous year, and that of late-flowering plants primarily by temperatures 2 years earlier. Subarctic plants develop leaf primordia one or more years prior to flowering (preformation); these results suggest that temperature affects the development of flower primordia during this preformation period. Together, increased variance in temperature and lag effects interacted with a changing mean to reduce the expected phenological advance by 94%, a magnitude large enough to account for our inability to detect a significant advance over time. We conclude that changes in temperature variability and lag effects can alter trends in plant responses to a warming climate and that predictions for changes in plant phenology under future warming scenarios should incorporate such effects.
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Affiliation(s)
- Christa P H Mulder
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, 99775-7000, USA
| | - David T Iles
- Department of Wildland Resources, Utah State University, Logan, Utah, 84322, USA
| | - Robert F Rockwell
- Department of Ornithology, Division of Vertebrate Zoology, American Museum of Natural History, New York, NY, 10024, USA
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10
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Spellman KV, Deutsch A, Mulder CPH, Carsten‐Conner LD. Metacognitive learning in the ecology classroom: A tool for preparing problem solvers in a time of rapid change? Ecosphere 2016. [DOI: 10.1002/ecs2.1411] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Katie V. Spellman
- Department of Biology and Wildlife Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska 99775 USA
| | - Andrea Deutsch
- North Pole Middle School Fairbanks North Star Borough School District Fairbanks Alaska 99701 USA
| | - Christa P. H. Mulder
- Department of Biology and Wildlife Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska 99775 USA
| | - Laura D. Carsten‐Conner
- College of Natural Science and Mathematics Geophysical Institute University of Alaska Fairbanks Fairbanks Alaska 99775 USA
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11
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Ruess RW, Uliassi DD, Mulder CPH, Person BT. Growth responses ofCarex ramenskiito defoliation, salinity, and nitrogen availability: Implications for geese-ecosystem dynamics in western Alaska. Écoscience 2016. [DOI: 10.1080/11956860.1997.11682392] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Koricheva J, Mulder CPH, Schmid B, Joshi J, Huss-Danell K. Numerical responses of different trophic groups of invertebrates to manipulations of plant diversity in grasslands. Oecologia 2014; 125:271-282. [PMID: 24595838 DOI: 10.1007/s004420000450] [Citation(s) in RCA: 242] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/1999] [Accepted: 04/28/2000] [Indexed: 12/01/2022]
Abstract
We studied the effects of plant diversity on abundance of invertebrate herbivores, parasitoids and predators in two grassland communities (one in Switzerland and one in Sweden) in which plant species richness and functional diversity have been experimentally manipulated. Among herbivores, the abundance of only the most sessile and specialised groups (leafhoppers and wingless aphids) was affected by plant diversity. At both sites, numbers of leafhoppers in sweep net samples showed a linear, negative relationship with plant species number whereas numbers of wingless aphids in suction samples increased with the number of plant functional groups (grasses, legumes, and non-legume forbs) present in the plot. Activity of carabid beetles and spiders (as revealed by pitfall catches) and the total number of predators in pitfalls at the Swiss site decreased linearly with increases in the number of plant species and plant functional groups. Abundance of more specialised enemies, hymenopteran parasitoids, was not affected by the manipulations of plant diversity. Path analysis and analysis of covariance indicated that plant diversity effects on invertebrate abundance were mostly indirect and mediated by changes in plant biomass and cover. At both sites, plant species composition (i.e. the identity of plant species in a mixture) affected numbers of most of the examined groups of invertebrates and was, therefore, a more important determinant of invertebrate abundance in grasslands than plant species richness per se or the number of plant functional groups. The presence of legumes in a mixture was especially important and led to higher numbers of most invertebrate groups. The similarity of invertebrate responses to plant diversity at the two study sites indicates that general patterns in abundance of different trophic groups can be detected across plant diversity gradients under different environmental conditions.
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Affiliation(s)
- Julia Koricheva
- Institut für Umweltwissenschaften, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland, Switzerland
- Section of Ecology, Department of Biology, University of Turku, FIN-20014 Turku, Finland, Finland
| | - Christa P H Mulder
- Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences, Box 4097, 90403 Umeå, Sweden, Sweden
- Department of Forest Ecology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden, Sweden
| | - Bernhard Schmid
- Institut für Umweltwissenschaften, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland, Switzerland
| | - Jasmin Joshi
- Institut für Umweltwissenschaften, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland, Switzerland
| | - Kerstin Huss-Danell
- Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences, Box 4097, 90403 Umeå, Sweden, Sweden
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13
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Roy BA, Mulder CPH. Pathogens, herbivores, and phenotypic plasticity of borealVaccinium vitis-idaeaexperiencing climate change. Ecosphere 2014. [DOI: 10.1890/es13-00271.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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14
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Moles AT, Peco B, Wallis IR, Foley WJ, Poore AGB, Seabloom EW, Vesk PA, Bisigato AJ, Cella-Pizarro L, Clark CJ, Cohen PS, Cornwell WK, Edwards W, Ejrnaes R, Gonzales-Ojeda T, Graae BJ, Hay G, Lumbwe FC, Magaña-Rodríguez B, Moore BD, Peri PL, Poulsen JR, Stegen JC, Veldtman R, von Zeipel H, Andrew NR, Boulter SL, Borer ET, Cornelissen JHC, Farji-Brener AG, DeGabriel JL, Jurado E, Kyhn LA, Low B, Mulder CPH, Reardon-Smith K, Rodríguez-Velázquez J, De Fortier A, Zheng Z, Blendinger PG, Enquist BJ, Facelli JM, Knight T, Majer JD, Martínez-Ramos M, McQuillan P, Hui FKC. Correlations between physical and chemical defences in plants: tradeoffs, syndromes, or just many different ways to skin a herbivorous cat? New Phytol 2013; 198:252-263. [PMID: 23316750 DOI: 10.1111/nph.12116] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 11/27/2012] [Indexed: 05/25/2023]
Abstract
Most plant species have a range of traits that deter herbivores. However, understanding of how different defences are related to one another is surprisingly weak. Many authors argue that defence traits trade off against one another, while others argue that they form coordinated defence syndromes. We collected a dataset of unprecedented taxonomic and geographic scope (261 species spanning 80 families, from 75 sites across the globe) to investigate relationships among four chemical and six physical defences. Five of the 45 pairwise correlations between defence traits were significant and three of these were tradeoffs. The relationship between species' overall chemical and physical defence levels was marginally nonsignificant (P = 0.08), and remained nonsignificant after accounting for phylogeny, growth form and abundance. Neither categorical principal component analysis (PCA) nor hierarchical cluster analysis supported the idea that species displayed defence syndromes. Our results do not support arguments for tradeoffs or for coordinated defence syndromes. Rather, plants display a range of combinations of defence traits. We suggest this lack of consistent defence syndromes may be adaptive, resulting from selective pressure to deploy a different combination of defences to coexisting species.
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Affiliation(s)
- Angela T Moles
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Begoña Peco
- Terrestrial Ecology Group, Departamento Interuniversitario de Ecología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin s/n, Cantoblanco, E-28049, Madrid, Spain
| | - Ian R Wallis
- Research School of Biology, Australian National University, Canberra, ACT, 0200, Australia
| | - William J Foley
- Research School of Biology, Australian National University, Canberra, ACT, 0200, Australia
| | - Alistair G B Poore
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN, 55108, USA
| | - Peter A Vesk
- School of Botany, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Alejandro J Bisigato
- Centro Nacional Patagónico, CONICET, Blvd. Brown s/n, 9120, Puerto Madryn, Argentina
| | | | - Connie J Clark
- Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA, 02540, USA
| | - Philippe S Cohen
- Jasper Ridge Biological Preserve, Stanford University, Stanford, CA, 94305-5020, USA
| | - William K Cornwell
- Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit, Amsterdam, the Netherlands
| | - Will Edwards
- School of Marine and Tropical Biology and Centre for Tropical Environmental and Sustainability Science, James Cook University, PO Box 6811, Cairns, QLD, Australia
| | - Rasmus Ejrnaes
- National Environmental Research Institute, University of Aarhus, 8420, Rønde, Denmark
| | - Therany Gonzales-Ojeda
- Facultad de Ciencias Forestales y Medio Ambiente, Universidad Nacional de San Antonio Abad del Cusco, Jr. San Mart í n 451, Madre de Dios, Peru
| | - Bente J Graae
- Climate Impacts Research Centre, Department of Ecology and Environmental Sciences, Umeå University, Abisko Naturvetenskapliga Station, 98107, Abisko, Sweden
- Department of Biology, NTNU, 7491, Trondheim, Norway
| | - Gregory Hay
- School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Fainess C Lumbwe
- Department of Biological Sciences, University of Zambia, PO Box 32379, Lusaka, 10101, Zambia
| | - Benjamín Magaña-Rodríguez
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
| | - Ben D Moore
- School of Marine and Tropical Biology, James Cook University, Townsville, QLD, 4811, Australia
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Pablo L Peri
- Universidad Nacional de la Patagonia Austral, INTA, CONICET, 9400, Rio Gallegos, Santa Cruz, Argentina
| | - John R Poulsen
- Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA, 02540, USA
| | - James C Stegen
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Ruan Veldtman
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
- Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735, South Africa
| | - Hugo von Zeipel
- Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden
| | - Nigel R Andrew
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia
| | - Sarah L Boulter
- Environmental Futures Centre, Griffith School of Environment, Griffith University, Nathan, QLD, 4111, Australia
| | - Elizabeth T Borer
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN, 55108, USA
| | - Johannes H C Cornelissen
- Department of Systems Ecology, Institute of Ecological Science, Vrije Universiteit, De Boelelaan 1087, NL-1081 HV, Amsterdam, the Netherlands
| | | | - Jane L DeGabriel
- School of Marine and Tropical Biology, James Cook University, Townsville, QLD, 4811, Australia
| | - Enrique Jurado
- Facultad de Ciencias Forestales, University of Nuevo Leon, Linares, 67700, Mexico
| | - Line A Kyhn
- National Environmental Research Institute, Aarhus University, Frederiksborgvej 399, DK- 4000, Roskilde, Denmark
| | - Bill Low
- Low Ecological Services, PO Box 3130, Alice Springs, NT, 0871, Australia
| | - Christa P H Mulder
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Kathryn Reardon-Smith
- Australian Centre for Sustainable Catchments, University of Southern Queensland, Toowoomba, QLD, 4350, Australia
| | - Jorge Rodríguez-Velázquez
- Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Morelia, 58190, México
| | - An De Fortier
- Department of Zoology, University of Zululand, Private Bag x1001, Kwadlangezwa, 3886, Kwazulu-Natal, South Africa
| | - Zheng Zheng
- Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
| | - Pedro G Blendinger
- CONICET and Instituto de Ecología Regional, Universidad Nacional de Tucumán, Yerba Buena, 4107, Tucumán, Argentina
| | - Brian J Enquist
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | | | - Tiffany Knight
- Department of Biology, Washington University in St. Louis, Box 1137, St Louis, MO, 63105, USA
| | - Jonathan D Majer
- Curtin Institute for Biodiversity and Climate, Curtin University, PO Box U1987, Perth, WA, 6845, Australia
| | - Miguel Martínez-Ramos
- Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Morelia, 58190, México
| | - Peter McQuillan
- School of Geography & Environmental Studies, University of Tasmania, Hobart, TAS, 7001, Australia
| | - Francis K C Hui
- School of Mathematics and Statistics and Evolution & Ecology Research Centre, The University of New South Wales, Sydney, NSW, 2052, Australia
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Aubry LM, Rockwell RF, Cooch EG, Brook RW, Mulder CPH, Koons DN. Climate change, phenology, and habitat degradation: drivers of gosling body condition and juvenile survival in lesser snow geese. Glob Chang Biol 2013; 19:149-160. [PMID: 23504727 DOI: 10.1111/gcb.12013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Accepted: 08/15/2012] [Indexed: 06/01/2023]
Abstract
Nesting migratory geese are among the dominant herbivores in (sub) arctic environments, which have undergone unprecedented increases in temperatures and plant growing days over the last three decades. Within these regions, the Hudson Bay Lowlands are home to an overabundant breeding population of lesser snow geese that has dramatically damaged the ecosystem, with cascading effects at multiple trophic levels. In some areas the overabundance of geese has led to a drastic reduction in available forage. In addition, warming of this region has widened the gap between goose migration timing and plant green-up, and this 'mismatch' between goose and plant phenologies could in turn affect gosling development. The dual effects of climate change and habitat quality on gosling body condition and juvenile survival are not known, but are critical for predicting population growth and related degradation of (sub) arctic ecosystems. To address these issues, we used information on female goslings marked and measured between 1978 and 2005 (4125 individuals). Goslings that developed within and near the traditional center of the breeding colony experienced the effects of long-term habitat degradation: body condition and juvenile survival declined over time. In newly colonized areas, however, we observed the opposite pattern (increase in body condition and juvenile survival). In addition, warmer than average winters and summers resulted in lower gosling body condition and first-year survival. Too few plant 'growing days' in the spring relative to hatch led to similar results. Our assessment indicates that geese are recovering from habitat degradation by moving to newly colonized locales. However, a warmer climate could negatively affect snow goose populations in the long-run, but it will depend on which seasons warm the fastest. These antagonistic mechanisms will require further study to help predict snow goose population dynamics and manage the trophic cascade they induce.
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Affiliation(s)
- Lise M Aubry
- Department of Wildland Resources and the Berryman Institute, Utah State University, 5230 Old Main Hill, Logan, UT 84322-5230, USA.
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Moles AT, Wallis IR, Foley WJ, Warton DI, Stegen JC, Bisigato AJ, Cella-Pizarro L, Clark CJ, Cohen PS, Cornwell WK, Edwards W, Ejrnaes R, Gonzales-Ojeda T, Graae BJ, Hay G, Lumbwe FC, Magaña-Rodríguez B, Moore BD, Peri PL, Poulsen JR, Veldtman R, von Zeipel H, Andrew NR, Boulter SL, Borer ET, Campón FF, Coll M, Farji-Brener AG, De Gabriel J, Jurado E, Kyhn LA, Low B, Mulder CPH, Reardon-Smith K, Rodríguez-Velázquez J, Seabloom EW, Vesk PA, van Cauter A, Waldram MS, Zheng Z, Blendinger PG, Enquist BJ, Facelli JM, Knight T, Majer JD, Martínez-Ramos M, McQuillan P, Prior LD. Putting plant resistance traits on the map: a test of the idea that plants are better defended at lower latitudes. New Phytol 2011; 191:777-788. [PMID: 21539574 DOI: 10.1111/j.1469-8137.2011.03732.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
• It has long been believed that plant species from the tropics have higher levels of traits associated with resistance to herbivores than do species from higher latitudes. A meta-analysis recently showed that the published literature does not support this theory. However, the idea has never been tested using data gathered with consistent methods from a wide range of latitudes. • We quantified the relationship between latitude and a broad range of chemical and physical traits across 301 species from 75 sites world-wide. • Six putative resistance traits, including tannins, the concentration of lipids (an indicator of oils, waxes and resins), and leaf toughness were greater in high-latitude species. Six traits, including cyanide production and the presence of spines, were unrelated to latitude. Only ash content (an indicator of inorganic substances such as calcium oxalates and phytoliths) and the properties of species with delayed greening were higher in the tropics. • Our results do not support the hypothesis that tropical plants have higher levels of resistance traits than do plants from higher latitudes. If anything, plants have higher resistance toward the poles. The greater resistance traits of high-latitude species might be explained by the greater cost of losing a given amount of leaf tissue in low-productivity environments.
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Affiliation(s)
- Angela T Moles
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
- Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Ian R Wallis
- Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
| | - William J Foley
- Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
| | - David I Warton
- School of Mathematics and Statistics and Evolution & Ecology Research Centre, The University of New South Wales, Sydney, NSW 2052, Australia
| | - James C Stegen
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
| | - Alejandro J Bisigato
- Centro Nacional Patagónico, CONICET, Blvd. Brown s/n, 9120 Puerto Madryn, Argentina
| | | | - Connie J Clark
- Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540, USA
| | - Philippe S Cohen
- Jasper Ridge Biological Preserve, Stanford University, Stanford, CA 94305-5020, USA
| | - William K Cornwell
- Biodiversity Research Centre, University of British Columbia, Vancouver BC, V6T 1Z4, Canada
| | - Will Edwards
- School of Marine and Tropical Biology, James Cook University, PO Box 6811, Cairns, Australia
| | - Rasmus Ejrnaes
- National Environmental Research Institute, University of Aarhus, 8420 Rønde, Denmark
| | - Therany Gonzales-Ojeda
- Facultad de Ciencias Forestales y Medio Ambiente, Universidad Nacional de San Antonio Abad del Cusco, Jr. San Martín 451, Madre de Dios, Peru
| | - Bente J Graae
- Climate Impacts Research Centre, Department of Ecology and Environmental Sciences, Umeå University, Abisko Naturvetenskapliga Station, 98107 Abisko, Sweden
- Department of Biology, NTNU, 7491 Trondheim, Norway
| | - Gregory Hay
- School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Fainess C Lumbwe
- Department of Biological Sciences, University of Zambia, PO Box 32379, Lusaka 10101, Zambia
| | - Benjamín Magaña-Rodríguez
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
| | - Ben D Moore
- School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia
- Ecology Group, Macaulay Land Use Research Institute, Aberdeen AB15 8QH, UK
| | - Pablo L Peri
- INTA, CONICET, Universidad Nacional de la Patagonia Austral, 9400 Rio Gallegos, Santa Cruz, Argentina
| | - John R Poulsen
- Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540, USA
| | - Ruan Veldtman
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Private Bag X7, Claremont 7735, South Africa
| | - Hugo von Zeipel
- Department of Natural Sciences, Mid Sweden University, SE-851 70 Sundsvall, Sweden
| | - Nigel R Andrew
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
| | - Sarah L Boulter
- Environmental Futures Centre, Griffith School of Environment, Griffith University, Nathan, QLD 4111, Australia
| | - Elizabeth T Borer
- Department of Ecology, Evolution and Behavior, University of Minnesota, St Paul, MN 55108, USA
| | - Florencia Fernández Campón
- Laboratorio de Entomología, CCT Mendoza-CONICET Av. Ruiz Leal s/n, Parque Gral. San Martín, Mendoza 5500, Argentina
| | - Moshe Coll
- Department of Entomology, Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel
| | | | - Jane De Gabriel
- School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia
| | - Enrique Jurado
- Facultad de Ciencias Forestales, University of Nuevo Leon, Linares 67700, Mexico
| | - Line A Kyhn
- National Environmental Research Institute, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
| | - Bill Low
- Low Ecological Services, PO Box 3130, Alice Springs, NT 0871, Australia
| | - Christa P H Mulder
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Kathryn Reardon-Smith
- Australian Centre for Sustainable Catchments, University of Southern Queensland, Toowoomba, QLD 4350, Australia
| | - Jorge Rodríguez-Velázquez
- Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Morelia 58190, México
| | - Eric W Seabloom
- Department of Ecology, Evolution and Behavior, University of Minnesota, St Paul, MN 55108, USA
| | - Peter A Vesk
- School of Botany, University of Melbourne, Parkville, Vic. 3010, Australia
| | - An van Cauter
- Department of Botany, University of Cape Town, Private Bag X1, Rhondebosch 7700, South Africa
| | - Matthew S Waldram
- Department of Botany, University of Cape Town, Private Bag X1, Rhondebosch 7700, South Africa
- Department of Geography, University of Leicester, Leicester LE1 7RH, UK
| | - Zheng Zheng
- Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
| | - Pedro G Blendinger
- CONICET and Instituto de Ecología Regional, Universidad Nacional de Tucumán, Yerba Buena 4107, Tucumán, Argentina
| | - Brian J Enquist
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Jose M Facelli
- School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Tiffany Knight
- Department of Biology, Washington University in St Louis, Box 1137, St Louis, MO 63105, USA
| | - Jonathan D Majer
- Curtin Institute for Biodiversity and Climate, Curtin University, PO Box U1987, Perth, WA 6845, Australia
| | - Miguel Martínez-Ramos
- Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Morelia 58190, México
| | - Peter McQuillan
- School of Geography & Environmental Studies, University of Tasmania, Hobart, TAS 7001, Australia
| | - Lynda D Prior
- School of Plant Science, University of Tasmania, Hobart, TAS 7001, Australia
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Rohrs-Richey JK, Mulder CPH, Winton LM, Stanosz G. Physiological performance of an Alaskan shrub (Alnus fruticosa) in response to disease (Valsa melanodiscus) and water stress. New Phytol 2011; 189:295-307. [PMID: 20868393 DOI: 10.1111/j.1469-8137.2010.03472.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
• Following the decades-long warming and drying trend in Alaska, there is mounting evidence that temperature-induced drought stress is associated with disease outbreaks in the boreal forest. Recent evidence of this trend is an outbreak of Cytospora canker disease (fungal pathogen Valsa melanodiscus (anamorph = Cytospora umbrina)) on Alnus species. • For Alnus fruticosa, we examined the effects of water stress on disease predisposition, and the effects of disease and water stress on host physiology. In two trials, we conducted a full-factorial experiment that crossed two levels of water stress with three types of inoculum (two isolates of V. melanodiscus, one control isolate). • Water stress was not required for disease predisposition. However, the effects of water stress and disease on host physiology were greatest near the peak phenological stage of the host and during hot, dry conditions. During this time, water stress and disease reduced light-saturated photosynthesis (-30%), light saturation point (-60%) and stomatal conductance (-40%). • Our results depended on the timing of water stress and disease in relation to host phenology and the environment. These factors should not be overlooked in attempts to generalize predictions about the role of temperature-induced drought stress in this pathosystem.
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Hector A, Hautier Y, Saner P, Wacker L, Bagchi R, Joshi J, Scherer-Lorenzen M, Spehn EM, Bazeley-White E, Weilenmann M, Caldeira MC, Dimitrakopoulos PG, Finn JA, Huss-Danell K, Jumpponen A, Mulder CPH, Palmborg C, Pereira JS, Siamantziouras ASD, Terry AC, Troumbis AY, Schmid B, Loreau M. General stabilizing effects of plant diversity on grassland productivity through population asynchrony and overyielding. Ecology 2010; 91:2213-20. [PMID: 20836442 DOI: 10.1890/09-1162.1] [Citation(s) in RCA: 227] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Insurance effects of biodiversity can stabilize the functioning of multispecies ecosystems against environmental variability when differential species' responses lead to asynchronous population dynamics. When responses are not perfectly positively correlated, declines in some populations are compensated by increases in others, smoothing variability in ecosystem productivity. This variance reduction effect of biodiversity is analogous to the risk-spreading benefits of diverse investment portfolios in financial markets. We use data from the BIODEPTH network of grassland biodiversity experiments to perform a general test for stabilizing effects of plant diversity on the temporal variability of individual species, functional groups, and aggregate communities. We tested three potential mechanisms: reduction of temporal variability through population asynchrony; enhancement of long-term average performance through positive selection effects; and increases in the temporal mean due to overyielding. Our results support a stabilizing effect of diversity on the temporal variability of grassland aboveground annual net primary production through two mechanisms. Two-species communities with greater population asynchrony were more stable in their average production over time due to compensatory fluctuations. Overyielding also stabilized productivity by increasing levels of average biomass production relative to temporal variability. However, there was no evidence for a performance-enhancing effect on the temporal mean through positive selection effects. In combination with previous work, our results suggest that stabilizing effects of diversity on community productivity through population asynchrony and overyielding appear to be general in grassland ecosystems.
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Affiliation(s)
- A Hector
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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Rixen C, Mulder CPH. Species removal and experimental warming in a subarctic tundra plant community. Oecologia 2009; 161:173-86. [DOI: 10.1007/s00442-009-1369-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Accepted: 04/30/2009] [Indexed: 11/28/2022]
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Towns DR, Wardle DA, Mulder CPH, Yeates GW, Fitzgerald BM, Richard Parrish G, Bellingham PJ, Bonner KI. Predation of seabirds by invasive rats: multiple indirect consequences for invertebrate communities. OIKOS 2009. [DOI: 10.1111/j.1600-0706.2008.17186.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wardle DA, Bellingham PJ, Bonner KI, Mulder CPH. Indirect effects of invasive predators on litter decomposition and nutrient resorption on seabird-dominated islands. Ecology 2009; 90:452-64. [DOI: 10.1890/08-0097.1] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Mulder CPH, Grant-Hoffman MN, Towns DR, Bellingham PJ, Wardle DA, Durrett MS, Fukami T, Bonner KI. Direct and indirect effects of rats: does rat eradication restore ecosystem functioning of New Zealand seabird islands? Biol Invasions 2008. [DOI: 10.1007/s10530-008-9396-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Despite recent interest in understanding the effects of human-induced global change on carbon (C) storage in terrestrial ecosystems, most studies have overlooked the influence of a major element of global change, namely biological invasions. We quantified ecosystem C storage, both above- and below-ground, on each of 18 islands off the coast of New Zealand. Some islands support high densities of nesting seabirds, while others have been invaded by predatory rats and host few seabirds. Our results show that, by preying upon seabirds, rats have indirectly enhanced C sequestration in live plant biomass by 104%, reduced C sequestration in non-living pools by 26% and increased total ecosystem C storage by 37%. Given the current worldwide distribution of rats and other invasive predatory mammals, and the consequent disappearance of seabird colonies, these predators may be important determinants of ecosystem C sequestration.
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Affiliation(s)
- David A Wardle
- Landcare Research, PO Box 40, Lincoln 7640, New Zealand.
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Fukami T, Wardle DA, Bellingham PJ, Mulder CPH, Towns DR, Yeates GW, Bonner KI, Durrett MS, Grant-Hoffman MN, Williamson WM. Above- and below-ground impacts of introduced predators in seabird-dominated island ecosystems. Ecol Lett 2006; 9:1299-307. [PMID: 17118004 DOI: 10.1111/j.1461-0248.2006.00983.x] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Predators often exert multi-trophic cascading effects in terrestrial ecosystems. However, how such predation may indirectly impact interactions between above- and below-ground biota is poorly understood, despite the functional importance of these interactions. Comparison of rat-free and rat-invaded offshore islands in New Zealand revealed that predation of seabirds by introduced rats reduced forest soil fertility by disrupting sea-to-land nutrient transport by seabirds, and that fertility reduction in turn led to wide-ranging cascading effects on belowground organisms and the ecosystem processes they drive. Our data further suggest that some effects on the belowground food web were attributable to changes in aboveground plant nutrients and biomass, which were themselves related to reduced soil disturbance and fertility on invaded islands. These results demonstrate that, by disrupting across-ecosystem nutrient subsidies, predators can indirectly induce strong shifts in both above- and below-ground biota via multiple pathways, and in doing so, act as major ecosystem drivers.
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Rixen C, Mulder CPH. Improved water retention links high species richness with increased productivity in arctic tundra moss communities. Oecologia 2005; 146:287-99. [PMID: 16044351 DOI: 10.1007/s00442-005-0196-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 06/23/2005] [Indexed: 11/25/2022]
Abstract
A positive relationship between plant species richness and ecosystem functioning has been found in a number of experimental studies. Positive species interactions at high species numbers have been suggested as a cause, but mechanisms driving positive interactions have not often been tested. In this experiment we asked three questions: (1) What is the relationship between species richness and productivity in experimentally constructed moss communities? (2) Is this relationship affected by plant density? and (3) Can changes in moisture absorption and retention explain observed relationships? To answer these questions we exposed arctic tundra moss communities of different species richness levels (1-11 species) and two different densities in the greenhouse to two levels of drought (short and long). Biomass (by the community and individual species), height and community moisture absorption and retention were measured as response variables. High species diversity increased productivity (more so in low-density plots than in high-density plots), but only when plots were watered regularly. Plot moisture retention was improved at high species richness as well, and plant height and variation in height was increased compared to plants in monoculture. Under high-density and short-drought conditions 10 out of 12 species grew better in mixture than in monoculture, but under the long drought treatment only six species did. A positive feedback loop between biomass and improved humidity under high diversity was supported by path analysis. We conclude that in this community the relationship between species richness and productivity depends on moisture availability and density, with improved water absorption and retention likely to be the mechanism for increased plant growth when drought periods are short. Furthermore, since this is the opposite of what has been found for temperate moss communities, conclusions from one system cannot automatically be extrapolated to other systems.
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Affiliation(s)
- Christian Rixen
- Institute of Arctic Biology, University of Alaska Fairbanks, USA.
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Armbruster WS, Mulder CPH, Baldwin BG, Kalisz S, Wessa B, Nute H. Comparative analysis of late floral development and mating-system evolution in tribe Collinsieae (Scrophulariaceae s.l.). Am J Bot 2002; 89:37-49. [PMID: 21669710 DOI: 10.3732/ajb.89.1.37] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Species of Collinsia and Tonella, the two sister genera of self-compatible annuals that constitute tribe Collinsieae, show extensive variation in floral size and morphology and in patterns of stamen and style elongation during the life of the flower (anthesis). We used a nuclear ribosomal ITS phylogeny, independent contrasts, and phylogenetically corrected path analysis to explore the patterns of covariance of the developmental and morphological traits potentially influencing mating system. Large-flowered taxa maintain herkogamy (spatial separation of anthers and stigmas) early in anthesis by differential elongation of staminal filaments, which positions each of the four anthers at the tip of the "keel" upon dehiscence. Small-flowered taxa do not show this pattern of filament elongation. The styles of large-flowered taxa elongate late in the 2-5 d of anthesis, resulting in late anther-stigma contact and delayed self-pollination. Anther-stigma contact and self-pollination occur early in anthesis in small-flowered species/populations. Thus, we found complex covariation of morphological and developmental traits that can be interpreted as the result of multitrait adaptation for early selfing and high levels of autogamy, delayed selfing and higher levels of outcrossing, or intermediate levels of outcrossing. Continuous variation in these traits suggests the operation of continuous variation in selective optima or the combined effects of divergent selection and phylogenetic inertia.
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Affiliation(s)
- W Scott Armbruster
- Department of Botany, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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