scholarly journals Increasing temporal variance leads to stable species range limits

2021 ◽  
Author(s):  
John W Benning ◽  
Ruth A Hufbauer ◽  
Christopher Weiss-Lehman
Keyword(s):  
Environmental Gradient ◽  
Environmental Gradients ◽  
Local Population ◽  
Evolutionary Model ◽  
Environmental Variation ◽  
Species Range ◽  
Range Limits ◽  
Stable Range ◽  
Species Expansion ◽  
Temporal Variance

What prevents populations of a species from adapting to the novel environments outside the species' geographic distribution? Previous models highlighted how gene flow across spatial environmental gradients determines species expansion vs. extinction and the location of species range limits. However, space is only one of two axes of environmental variation — environments also vary in time, and we know temporal environmental variation has important consequences for population demography and evolution. We used an individual based evolutionary model to explore how temporal stochasticity in environmental conditions influences the spread of populations across a spatial environmental gradient. We find that temporal stochasticity greatly alters our predictions for range dynamics compared to temporally static environments. When temporal variance is equal across the landscape, the fate of species (expansion vs. extinction) is determined by the interaction between the degree of temporal autocorrelation in environmental fluctuations and the steepness of the spatial environmental gradient. When the magnitude of temporal variance changes across the landscape, stable range limits form where this variance becomes large enough to prevent local population adaptation and persistence. These results illustrate the pivotal influence of temporal stochasticity on the likelihood of populations colonizing novel habitats and the location of species range limits.

scholarly journals Environmental association modelling with loci under divergent selection predicts the distribution range of a lizard

2021 ◽  
Author(s):  
Alejandro Llanos-Garrido ◽  
Andrea Briega-Álvarez ◽  
Javier Pérez-Tris ◽  
José Díaz
Keyword(s):  
Genetic Variation ◽  
Environmental Gradient ◽  
Environmental Variation ◽  
Western Mediterranean ◽  
Distribution Range ◽  
Species Range ◽  
Adaptive Genetic Variation ◽  
Temperature And Precipitation ◽  
Psammodromus Algirus ◽  
Geographical Expansion

During geographical expansion of a species individual colonizers have to confront different ecological challenges, and the capacity of the species to broaden its range may depend on the total amount of adaptive genetic variation supplied by evolution. We set out to test whether the distribution of loci under selection along a contrasting environmental gradient can be turned into a model that accurately predicts a species’ range. If positive, this may shed light on the genetic source of adaptive limits that shape range boundaries. We sampled five populations of the western Mediterranean lizard Psammodromus algirus that inhabit a noticeable environmental gradient of temperature and precipitation. We used 21 SNPs putatively under selection to correlate the genotypes of 95 individuals with environmental variation among their populations, using 1x1 km2 grid cells as sampling units. By extrapolating the resulting model to all possible combinations of alleles, we inferred the locations that were theoretically suitable for the species. The inferred distribution range overlapped to a large extent with the realized range of the species, including an accurate prediction of internal gaps and range borders. Our results suggest an adaptability threshold determined by the amount of genetic variation available that would be required to warrant adaptation beyond a certain limit of environmental variation. These results support the idea that the expansion of a species’ range may be ultimately linked to the arising of new variants under selection.

scholarly journals Environmental Variation and How its Spatial Structure Influences the Cross-Shelf Distribution of High-Latitude Coral Communities in South Africa

Diversity ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 57 ◽  
Author(s):  
Sean N. Porter ◽  
Michael H. Schleyer
Keyword(s):  
South Africa ◽  
Continental Shelf ◽  
High Latitude ◽  
Environmental Variables ◽  
Environmental Gradients ◽  
High Tide ◽  
Environmental Variation ◽  
Shelf Edge ◽  
Spatial Differences ◽  
Coral Communities

Coral communities display spatial patterns. These patterns can manifest along a coastline as well as across the continental shelf due to ecological interactions and environmental gradients. Several abiotic surrogates for environmental variables are hypothesised to structure high-latitude coral communities in South Africa along and across its narrow shelf and were investigated using a correlative approach that considered spatial autocorrelation. Surveys of sessile communities were conducted on 17 reefs and related to depth, distance to high tide, distance to the continental shelf edge and to submarine canyons. All four environmental variables were found to correlate significantly with community composition, even after the effects of space were removed. The environmental variables accounted for 13% of the variation in communities; 77% of this variation was spatially structured. Spatially structured environmental variation unrelated to the environmental variables accounted for 39% of the community variation. The Northern Reef Complex appears to be less affected by oceanic factors and may undergo less temperature variability than the Central and Southern Complexes; the first is mentioned because it had the lowest canyon effect and was furthest from the continental shelf, whilst the latter complexes had the highest canyon effects and were closest to the shelf edge. These characteristics may be responsible for the spatial differences in the coral communities.

scholarly journals Testing for local adaptation and evolutionary potential along 1 altitudinal gradients in rainforest Drosophila: beyond laboratory estimates

2016 ◽  
Author(s):  
Eleanor K. O’Brien ◽  
Megan Higgie ◽  
Alan Reynolds ◽  
Ary A. Hoffmann ◽  
Jon R. Bridle
Keyword(s):  
Genetic Variation ◽  
Environmental Change ◽  
High Altitude ◽  
Local Adaptation ◽  
Biotic Interactions ◽  
Environmental Variation ◽  
Species Range ◽  
Altitudinal Gradients ◽  
Low Altitude ◽  
The Relationship

ABSTRACTPredicting how species will respond to the rapid climatic changes predicted this century is an urgent task. Species Distribution Models (SDMs) use the current relationship between environmental variation and species’ abundances to predict the effect of future environmental change on their distributions. However, two common assumptions of SDMs are likely to be violated in many cases: (1) that the relationship of environment with abundance or fitness is constant throughout a species’ range and will remain so in future, and (2) that abiotic factors (e.g. temperature, humidity) determine species’ distributions. We test these assumptions by relating field abundance of the rainforest fruit fly Drosophila birchii to ecological change across gradients that include its low and high altitudinal limits. We then test how such ecological variation affects the fitness of 35 D. birchii families transplanted in 591 cages to sites along two altitudinal gradients, to determine whether genetic variation in fitness responses could facilitate future adaptation to environmental change. Overall, field abundance was highest at cooler, high altitude sites, and declined towards warmer, low altitude sites. By contrast, cage fitness (productivity) increased towards warmer, lower altitude sites, suggesting that biotic interactions (absent from cages) drive ecological limits at warmer margins. In addition, the relationship between environmental variation and abundance varied significantly among gradients, indicating divergence in ecological niche across the species’ range. However, there was no evidence for local adaptation within gradients, despite greater productivity of high altitude than low altitude populations when families were reared under laboratory conditions. Families also responded similarly to transplantation along gradients, providing no evidence for fitness trade-offs that would favour local adaptation. These findings highlight the importance of (1) measuring genetic variation of key traits under ecologically relevant conditions, and (2) considering the effect of biotic interactions when predicting species’ responses to environmental change.

scholarly journals Distinguishing the signatures of local environmental filtering and regional trait range limits in the study of trait-environment relationships

2019 ◽  
Author(s):  
Pierre Denelle ◽  
Cyrille Violle ◽  
François Munoz
Keyword(s):  
Community Assembly ◽  
Environmental Gradients ◽  
Boundary Effect ◽  
Extreme Environments ◽  
Environmental Filtering ◽  
Range Limits ◽  
Species Pool ◽  
Statistical Tool ◽  
Leaf Trait ◽  
Trait Convergence

AbstractUnderstanding the imprint of environmental filtering on community assembly along environmental gradients is a key objective of trait-gradient analyses. Depending on local constraints, this filtering generally entails that species departing from an optimum trait value have lower abundances in the community. The Community-Weighted Mean (CWM) and Variance (CWV) of trait values are then expected to depict the optimum and intensity of filtering, respectively. However, the trait distribution within the regional species pool and its limits can also affect local CWM and CWV values apart from the effect of environmental filtering. The regional trait range limits are more likely to be reached in communities at the extremes of environmental gradients. Analogous to the mid-domain effect in biogeography, decreasing CWV values in extreme environments can then represent the influence of regional trait range limits rather than stronger filtering in the local environment. We name this effect the “Trait-Gradient Boundary Effect” (TGBE). First, we use a community assembly framework to build simulated communities along a gradient from a species pool and environmental filtering with either constant or varying intensity while accounting for immigration processes. We demonstrate the significant influence of TGBE, in parallel to environmental filtering, on CWM and CWV at the extremes of the environmental gradient. We provide a statistical tool based on Approximate Bayesian Computation to decipher the respective influence of local environmental filtering and regional trait range limits. Second, as a case study, we reanalyze the functional composition of alpine plant communities distributed along a gradient of snow cover duration. We show that leaf trait convergence found in communities at the extremes of the gradient reflect an influence of trait range limits rather than stronger environmental filtering. These findings challenge correlative trait-environment relationships and call for more explicitly identifying the mechanisms responsible of trait convergence/divergence along environmental gradients.

scholarly journals The emergent interactions that govern biodiversity change

2020 ◽  
Vol 117 (29) ◽  
pp. 17074-17083 ◽  
Author(s):  
James S. Clark ◽  
C. Lane Scher ◽  
Margaret Swift
Keyword(s):  
Species Interactions ◽  
Environmental Gradients ◽  
Local Population ◽  
Species Abundance ◽  
Community Change ◽  
Model Specification ◽  
Data Simulation ◽  
Breeding Bird ◽  
Probabilistic Uncertainty ◽  
Nonlinear Responses

Observational studies have not yet shown that environmental variables can explain pervasive nonlinear patterns of species abundance, because those patterns could result from (indirect) interactions with other species (e.g., competition), and models only estimate direct responses. The experiments that could extract these indirect effects at regional to continental scales are not feasible. Here, a biophysical approach quantifies environment– species interactions (ESI) that govern community change from field data. Just as species interactions depend on population abundances, so too do the effects of environment, as when drought is amplified by competition. By embedding dynamic ESI within framework that admits data gathered on different scales, we quantify responses that are induced indirectly through other species, including probabilistic uncertainty in parameters, model specification, and data. Simulation demonstrates that ESI are needed for accurate interpretation. Analysis demonstrates how nonlinear responses arise even when their direct responses to environment are linear. Applications to experimental lakes and the Breeding Bird Survey (BBS) yield contrasting estimates of ESI. In closed lakes, interactions involving phytoplankton and their zooplankton grazers play a large role. By contrast, ESI are weak in BBS, as expected where year-to-year movement degrades the link between local population growth and species interactions. In both cases, nonlinear responses to environmental gradients are induced by interactions between species. Stability analysis indicates stability in the closed-system lakes and instability in BBS. The probabilistic framework has direct application to conservation planning that must weigh risk assessments for entire habitats and communities against competing interests.

Niche Partitioning Among Snook (Pisces: Centropomidae) in Rivers of Southeastern Florida and Implications for Species Range Limits

2019 ◽  
Vol 43 (2) ◽  
pp. 396-408 ◽  
Author(s):  
Philip W. Stevens ◽  
Jynessa Dutka-Gianelli ◽  
Eric J. Nagid ◽  
Alexis A. Trotter ◽  
Kevin G. Johnson ◽  
...  
Keyword(s):  
Niche Partitioning ◽  
Species Range ◽  
Range Limits

scholarly journals Effects of environmental conditions and space on species turnover for three plant functional groups in Brazilian savannas

2019 ◽  
Vol 12 (6) ◽  
pp. 1047-1058 ◽  
Author(s):  
Hélio Menegat ◽  
Divino Vicente Silvério ◽  
Henrique A Mews ◽  
Guarino R Colli ◽  
Ana Clara Abadia ◽  
...  
Keyword(s):  
Functional Groups ◽  
Environmental Conditions ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Geographic Distance ◽  
Floristic Composition ◽  
Environmental Variation ◽  
Variance Partitioning ◽  
Plant Functional Groups ◽  
Palm Species

Abstract Aims Different plant functional groups display diverging responses to the same environmental gradients. Here, we assess the effects of environmental and spatial predictors on species turnover of three functional groups of Brazilian savannas (Cerrado) plants—trees, palms and lianas—across the transition zone between the Cerrado and Amazon biomes in central Brazil. Methods We used edaphic, climatic and plant composition data from nine one-hectare plots to assess the effects of the environment and space on species turnover using a Redundancy Analysis and Generalized Dissimilarity Modeling (GDM), associated with variance partitioning. Important Findings We recorded 167 tree species, 5 palms and 4 liana species. Environmental variation was most important in explaining species turnover, relative to geographic distance, but the best predictors differed between functional groups: geographic distance and silt for lianas; silt for palms; geographic distance, temperature and elevation for trees. Geographic distances alone exerted little influence over species turnover for the three functional groups. The pure environmental variation explained most of the liana and palm turnover, while tree turnover was largely explained by the shared spatial and environmental contribution. The effects of geographic distance upon species turnover leveled off at about 300 km for trees, and 200 km for lianas, whereas they were unimportant for palm species turnover. Our results indicate that environmental factors that determine floristic composition and species turnover differ substantially between plant functional groups in savannas. Therefore, we recommend that studies that aim to investigate the role of environmental conditions in determining plant species turnover should examine plant functional groups separately.

The demography of a dominant Amazon liana species exhibits little environmental sensitivity

2015 ◽  
Vol 32 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Luciana de Campos Franci ◽  
Jens-Christian Svenning ◽  
Henrik Balslev ◽  
Fernando Roberto Martins ◽  
Jacob Nabe-Nielsen
Keyword(s):  
Dominant Species ◽  
Environmental Gradients ◽  
Floristic Composition ◽  
Environmental Variation ◽  
Common Species ◽  
Amazon Forest ◽  
Vegetation Density ◽  
Vital Rates ◽  
Relative Growth ◽  
Positive Effect

Abstract:Despite its high plant diversity, the Amazon forest is dominated by a limited number of highly abundant, oligarchic tree and liana species. The high diversity can be related to specific habitat requirements in many of the less common species, but fewer studies have investigated the characteristics of the dominant species. To test how environmental variation may contribute to the success of dominant species we investigated whether the vital rates of the abundant liana Machaerium cuspidatum is sensitive to canopy height, topographic steepness, vegetation density, soil components and floristic composition across an Ecuadorian Amazon forest. The population was inventoried in 1998 and in 2009. Plants were divided into seedling-sized individuals, non-climbers and climbers. Out of 448 seedling-sized plants 421 died, 539 of 732 non-climbers died, and 107 of 198 climbers died. There was weak positive effect of dense understorey on the relative growth rate of climbers. The mortality of seedling-sized plants was higher in areas with intermediate slope, but for larger plants mortality was not related to environmental variation. The limited sensitivity of the vital rates to environmental gradients in the area suggests that ecological generalism contributes to the success of this dominant Amazonian liana.

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