Allee Effects Determine Pollinator Services at Local and Geographic Scales

Abstract Climatic factors have attracted much attention in the study of species’ distributions, while little is known about the role of biotic interactions. Here, we tested for variation in pollinator service across the distribution of a plant species, and evaluated the driving mechanisms. We monitored insect pollinators using time-lapse cameras in populations of North American Arabidopsis lyrata from the southern to the northern range limit. We spotted 67 pollinating insect taxa, indicating that this plant-pollinator network is a generalist system. Pollinator service increased with latitude. Higher pollinator visitation was correlated with the richness of other flowering plants and with plant census size, which was largest in northern populations. Furthermore, pollinator service reached a maximum at intermediate local flower density. Synthesis: This study indicates that pollination service underlies Allee effects on a local and species’ range scale, and that plant populations at range limits receive only marginal pollination service if they are small.

Download Full-text

Demographic effects of interacting species: exploring stable coexistence under increased climatic variability in a semiarid shrub community

Scientific Reports ◽

10.1038/s41598-021-82571-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ana I. García-Cervigón ◽

Pedro F. Quintana-Ascencio ◽

Adrián Escudero ◽

Merari E. Ferrer-Cervantes ◽

Ana M. Sánchez ◽

...

Keyword(s):

Population Dynamics ◽

Species Coexistence ◽

Climatic Factors ◽

Demographic Data ◽

Climatic Variability ◽

Biotic Interactions ◽

Vital Rates ◽

Climatic Fluctuations ◽

Demographic Models ◽

Shrub Community

AbstractPopulation persistence is strongly determined by climatic variability. Changes in the patterns of climatic events linked to global warming may alter population dynamics, but their effects may be strongly modulated by biotic interactions. Plant populations interact with each other in such a way that responses to climate of a single population may impact the dynamics of the whole community. In this study, we assess how climate variability affects persistence and coexistence of two dominant plant species in a semiarid shrub community on gypsum soils. We use 9 years of demographic data to parameterize demographic models and to simulate population dynamics under different climatic and ecological scenarios. We observe that populations of both coexisting species may respond to common climatic fluctuations both similarly and in idiosyncratic ways, depending on the yearly combination of climatic factors. Biotic interactions (both within and among species) modulate some of their vital rates, but their effects on population dynamics highly depend on climatic fluctuations. Our results indicate that increased levels of climatic variability may alter interspecific relationships. These alterations might potentially affect species coexistence, disrupting competitive hierarchies and ultimately leading to abrupt changes in community composition.

Download Full-text

The relative importance of factors determining genetic drift: mating system, spatial genetic structure, habitat and census size in Arabidopsis lyrata

New Phytologist ◽

10.1111/j.1469-8137.2010.03569.x ◽

2010 ◽

Vol 189 (4) ◽

pp. 1200-1209 ◽

Cited By ~ 30

Author(s):

Yvonne Willi ◽

Kirsti Määttänen

Keyword(s):

Genetic Structure ◽

Mating System ◽

Genetic Drift ◽

Spatial Genetic Structure ◽

Relative Importance ◽

Arabidopsis Lyrata ◽

Census Size

Download Full-text

Limited phenological and pollinator-mediated isolation among selfing and outcrossing Arabidopsis lyrata populations

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.2323 ◽

2020 ◽

Vol 287 (1939) ◽

pp. 20202323

Author(s):

Courtney E. Gorman ◽

Lindsay Bond ◽

Mark van Kleunen ◽

Marcel E. Dorken ◽

Marc Stift

Keyword(s):

Reproductive Isolation ◽

Mating System ◽

Common Garden ◽

Common Garden Experiment ◽

Pollinator Visitation ◽

Arabidopsis Lyrata ◽

Pollinator Preference ◽

Pollination Mechanisms ◽

Self Fertilization ◽

Mechanistic Basis

Transitions from outcrossing to selfing have been a frequent evolutionary shift in plants and clearly play a role in species divergence. However, many questions remain about the initial mechanistic basis of reproductive isolation during the evolution of selfing. For instance, how important are pre-zygotic pre-pollination mechanisms (e.g. changes in phenology and pollinator visitation) in maintaining reproductive isolation between newly arisen selfing populations and their outcrossing ancestors? To test whether changes in phenology and pollinator visitation isolate selfing populations of Arabidopsis lyrata from outcrossing populations, we conducted a common garden experiment with plants from selfing and outcrossing populations as well as their between-population hybrids. Specifically, we asked whether there was isolation between outcrossing and selfing plants and their between-population hybrids through differences in (1) the timing or intensity of flowering; and/or (2) pollinator visitation. We found that phenology largely overlapped between plants from outcrossing and selfing populations. There were also no differences in pollinator preference related to mating system. Additionally, pollinators preferred to visit flowers on the same plant rather than exploring nearby plants, creating a large opportunity for self-fertilization. Overall, this suggests that pre-zygotic pre-pollination mechanisms do not strongly reproductively isolate plants from selfing and outcrossing populations of Arabidopsis lyrata .

Download Full-text

Spatial scale modulates the strength of ecological processes driving disease distributions

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1521657113 ◽

2016 ◽

Vol 113 (24) ◽

pp. E3359-E3364 ◽

Cited By ~ 70

Author(s):

Jeremy M. Cohen ◽

David J. Civitello ◽

Amber J. Brace ◽

Erin M. Feichtinger ◽

C. Nicole Ortega ◽

...

Keyword(s):

Population Density ◽

Human Population ◽

Large Scale ◽

Climatic Factors ◽

Biotic Interactions ◽

Amphibian Declines ◽

Biotic Factors ◽

Human Population Density ◽

Single Scale ◽

Anthropogenic Modifications

Humans are altering the distribution of species by changing the climate and disrupting biotic interactions and dispersal. A fundamental hypothesis in spatial ecology suggests that these effects are scale dependent; biotic interactions should shape distributions at local scales, whereas climate should dominate at regional scales. If so, common single-scale analyses might misestimate the impacts of anthropogenic modifications on biodiversity and the environment. However, large-scale datasets necessary to test these hypotheses have not been available until recently. Here we conduct a cross-continental, cross-scale (almost five orders of magnitude) analysis of the influence of biotic and abiotic processes and human population density on the distribution of three emerging pathogens: the amphibian chytrid fungus implicated in worldwide amphibian declines and West Nile virus and the bacterium that causes Lyme disease (Borrelia burgdorferi), which are responsible for ongoing human health crises. In all three systems, we show that biotic factors were significant predictors of pathogen distributions in multiple regression models only at local scales (∼102–103 km2), whereas climate and human population density always were significant only at relatively larger, regional scales (usually >104 km2). Spatial autocorrelation analyses revealed that biotic factors were more variable at smaller scales, whereas climatic factors were more variable at larger scales, as is consistent with the prediction that factors should be important at the scales at which they vary the most. Finally, no single scale could detect the importance of all three categories of processes. These results highlight that common single-scale analyses can misrepresent the true impact of anthropogenic modifications on biodiversity and the environment.

Download Full-text

Morphological and Chemical Traits of Cladonia Respond to Multiple Environmental Factors in Acidic Dry Grasslands

Microorganisms ◽

10.3390/microorganisms9020453 ◽

2021 ◽

Vol 9 (2) ◽

pp. 453

Author(s):

Gabriele Gheza ◽

Luca Di Nuzzo ◽

Chiara Vallese ◽

Matteo Barcella ◽

Renato Benesperi ◽

...

Keyword(s):

Environmental Factors ◽

Vegetation Dynamics ◽

Climatic Factors ◽

Biotic Interactions ◽

Dry Grasslands ◽

Reproduction Strategies ◽

Colonization Patterns ◽

Chemical Traits ◽

Substrate Ph ◽

Terricolous Lichen

Terricolous lichen communities in lowlands occur especially in open dry habitats. Such communities are often dominated by species of the genus Cladonia, which are very variable in morphology, reproduction strategies, and secondary metabolites. In this work, we investigated traits-environment relationships considering vegetation dynamics, substrate pH, disturbance, and climate. A total of 122 plots were surveyed in 41 acidic dry grasslands in the western Po Plain (Northern Italy). Relationships between Cladonia traits and environmental variables were investigated by means of a model-based Fourth Corner Analysis. Thallus morphology and metabolites responded to vegetation dynamics, substrate pH, disturbance, and climate, whereas reproduction strategies responded only to vegetation dynamics. Traits’ correlations with vegetation dynamics elucidate their colonization patterns in open dry habitats or suggest biotic interactions with bryophytes and vascular plants. In addition, correlations between metabolites and environmental factors support interpretations of their ecological roles. Our results also stress the importance of studying traits’ relationships with climatic factors as an alert towards lichen reactions to climate change.

Download Full-text

Limited phenological and pollinator-mediated isolation among selfing and outcrossing Arabidopsis lyrata populations

10.1101/2019.12.17.879361 ◽

2019 ◽

Author(s):

Courtney E. Gorman ◽

Lindsay Bond ◽

Mark van Kleunen ◽

Marcel E. Dorken ◽

Marc Stift

Keyword(s):

Reproductive Isolation ◽

Common Garden ◽

F1 Hybrids ◽

Common Garden Experiment ◽

Pollinator Visitation ◽

Arabidopsis Lyrata ◽

Pollinator Preference ◽

Pollination Mechanisms ◽

Self Fertilization ◽

Mechanistic Basis

AbstractTransitions from outcrossing to selfing have been a frequent evolutionary shift in plants and clearly play a role in species divergence. However, many questions remain about the initial mechanistic basis of reproductive isolation during the evolution of selfing. For instance, how important are prezygotic pre-pollination mechanisms (e.g. changes in phenology and pollinator visitation) in maintaining reproductive isolation between newly arisen selfing populations and their outcrossing ancestors? To test whether changes in phenology and pollinator visitation isolate selfing populations of Arabidopsis lyrata from outcrossing populations, we conducted a common garden experiment with plants from selfing and outcrossing populations as well as their F1 hybrids. Specifically, we asked whether there was isolation between outcrossing and selfing plants and their F1 hybrids through differences in 1) the timing or intensity of flowering; and/or 2) pollinator visitation. We found that phenology largely overlapped between plants from outcrossing and selfing populations. There were also no differences in pollinator preference related to mating system. Additionally, pollinators preferred to visit flowers on the same plant rather than exploring nearby plants, creating a large opportunity for self-fertilization. Overall, this suggests that prezygotic pre-pollination mechanisms do not strongly reproductively isolate plants from selfing and outcrossing populations of Arabidopsis lyrata.

Download Full-text

Barriers to coexistence limit the poleward range of a globally-distributed plant

10.1101/2020.02.24.946574 ◽

2020 ◽

Author(s):

David W. Armitage ◽

Stuart E. Jones

Keyword(s):

Species Interactions ◽

Thermal Response ◽

Biotic Interactions ◽

Predictive Ability ◽

Range Limit ◽

Ecological Niche Models ◽

Limit Theory ◽

Coexistence Theory ◽

Species Tolerance ◽

Niche Models

AbstractSpecies’ poleward ranges are thought to be primarily limited by climatic constraints rather than biotic interactions such as competition. However, theory suggests that a species’ tolerance to competition is reduced in harsh environments, such as at the extremes of its climatic niche. This implies that under certain conditions, interspecific competition near species’ range margins can prevent the establishment of populations into otherwise tolerable environments and results in geographic distributions being shaped by the interaction of climate and competition. We test this prediction by challenging an experimentally-parameterized mechanistic competition model to predict the poleward range boundaries of two widely co-occurring and ecologically-similar aquatic duckweed plants. We show that simple, mechanistic ecological niche models which include competition and thermal response terms best predict the northern range limits of our study species, outperforming competition-free mechanistic models and matching the predictive ability of popular statistical niche models fit to occurrence records. Next, using the theoretical framework of modern coexistence theory, we show that relative nonlinearity in competitors’ responses to temperature fluctuations maintains coexistence at the subordinate competitor’s poleward range boundary, highlighting the importance of this underappreciated fluctuation-dependent coexistence mechanism. Our results demonstrate the predictive utility of mechanistic niche models and support a more nuanced, interactive role of climate and species interactions in determining range boundaries, which may help explain the conflicting results from previous tests of classic range limit theory and contribute to a more mechanistic understanding of range dynamics under global change.

Download Full-text

Non-climatic constraints on upper elevational plant range expansion under climate change

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.1779 ◽

2014 ◽

Vol 281 (1794) ◽

pp. 20141779 ◽

Cited By ~ 80

Author(s):

Carissa D. Brown ◽

Mark Vellend

Keyword(s):

Climate Change ◽

Range Expansion ◽

Fungal Pathogens ◽

Sugar Maple ◽

Climatic Factors ◽

Indirect Evidence ◽

Climatic Conditions ◽

Time Lags ◽

Range Limit ◽

Elevational Range

We are limited in our ability to predict climate-change-induced range shifts by our inadequate understanding of how non-climatic factors contribute to determining range limits along putatively climatic gradients. Here, we present a unique combination of observations and experiments demonstrating that seed predation and soil properties strongly limit regeneration beyond the upper elevational range limit of sugar maple, a tree species of major economic importance. Most strikingly, regeneration beyond the range limit occurred almost exclusively when seeds were experimentally protected from predators. Regeneration from seed was depressed on soil from beyond the range edge when this soil was transplanted to sites within the range, with indirect evidence suggesting that fungal pathogens play a role. Non-climatic factors are clearly in need of careful attention when attempting to predict the biotic consequences of climate change. At minimum, we can expect non-climatic factors to create substantial time lags between the creation of more favourable climatic conditions and range expansion.

Download Full-text