The importance of species pool size for community composition

Journal of Biogeography

et al. 2019

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Aim To assess richness patterns of ferns and lycophytes in relation to climatic factors in Eastern Asia, analysing eight elevational gradients, situated along a latitudinal gradient. Location East and Southeast Asia (4° S to 43.3° N). Methods Ferns and lycophytes were recorded in 480 plots of 400 m2 along eight elevational gradients. We related macroclimatic factors to local fern species richness using generalized linear models. We tested the predictive power of macroclimatic variables by a leave‐one‐(gradient‐) out cross‐validation (LOOCV) and tested the predictive power of each model using Spearman's rank correlation, and predicted the respective models spatially. Model residuals were related to two available local (plot scale) factors, terrain inclination and terrain heterogeneity using simple linear regression. Results Local fern species richness declined linearly towards higher latitudes, and simultaneously elevational richness peaks shifted towards lowlands with increasing distance from the equator, transitioning from unimodal to linear patterns. Temperature was the macroclimatic factor with the highest predictive power for fern species richness. In combination with other variables, especially cloud cover, macroclimatic factors could explain up to about 60% of species richness distributions. Main conclusions Macroclimatic factors, such as temperature and cloud cover, are able to predict a substantial proportion of the variation in local fern species richness in East and Southeast Asia. Using predictive models based on LOOCV substantially increases the accuracy of species richness predictions as compared to simply searching for correlates along all gradients.

Section: Discussionmentioning

confidence: 85%

Latitude‐independent, continent‐wide consistency in climate–richness relationships in Asian ferns and lycophytes

Khine

Kluge

Journal of Biogeography

et al. 2019

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“…The perception of processes that shape local community composition and diversity largely depends on the circumscription of the species pool (Kraft et al ., ; Anacker & Harrison, ; Lessard et al ., 2012a,b; Karger et al ., , ) and how this relates to the spatial and temporal scale of sampling (Tuomisto & Ruokolainen, ). Incorporating the probabilistic species pool into studies on community composition and diversity can help disentangle the strength of different processes that drive local species assembly and their geographical distribution.…”

Section: Prospects and Limitations Of Probabilistic Species Poolsmentioning

confidence: 99%

Delineating probabilistic species pools in ecology and biogeography

Karger

Cord

Global Ecology and Biogeography

et al. 2016

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Aim To provide a mechanistic and probabilistic framework for defining the species pool based on species-specific probabilities of dispersal, environmental suitability and biotic interactions within a specific temporal extent, and to show how probabilistic species pools can help disentangle the geographical structure of different community assembly processes.Innovation Probabilistic species pools provide an improved species pool definition based on probabilities in conjunction with the associated species list, which explicitly recognize the indeterminate nature of species pool membership for a given focal unit of interest and better capture real-world complexity. Probabilistic species pools provide a quantitative assessment of how dispersal, environmental or biotic factors influence estimates of species pool composition and size for a given temporal extent.Conclusions Based on one simulated and two empirical examples we demonstrate that probabilistic species pools allow us to disentangle the geographical variation in dispersal, environmental and biotic assembly processes for species assemblages in focal units. We also show that probabilistic species pools are fully compatible with traditional definitions of species pools and are applicable over a wide range of spatial and temporal extents. Additionally they are robust to missing data and provide a quantified and transparent approach to estimating the size and composition of species pools in a mechanistic way, providing a valuable tool for studies from community ecology to macroecology.

“…This varying combinations of factors allows the use of elevational gradients to disentangle the relative effects of different factors. Second, most mountains are spatially constricted to different geographical regions, implying that they have uniform regional species pools (Karger et al, ), which allows to address questions regarding the role of historical factors in determining the composition of communities (Rahbek et al, ; Karger et al, ; Lessard et al, ).…”

Section: Elevational Gradients As Systems To Study Evolutionary and Ementioning

confidence: 99%

Elevational diversity patterns as an example for evolutionary and ecological dynamics in ferns and lycophytes

J of Sytematics Evolution

Karger

Kluge

2016

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Evolutionary processes such as adaptation, ecological filtering, and niche conservatism involve the interaction of organisms with their environment and are thus commonly studied along environmental gradients. Elevational gradients have become among the most studied environmental gradients to understand large-scale patterns of species richness and composition because they are highly replicated with different combinations of geographical, environmental and historical factors. We here review the literature on using elevational gradients to understand evolutionary processes in ferns. Some phylogenetic studies of individual fern clades have considered elevation in the analysis or interpretation and postulated that fern diversification is linked to the colonization of mountain habitats. Other studies that have linked elevational community composition and hence ecological filtering with phylogenetic community composition and morphological traits, usually only found limited phylogenetic signal. However, these studies are ultimately only correlational, and there are few actual tests of the evolutionary mechanisms leading to these patterns. We identify a number of challenges for improving our understanding of how evolutionary and ecological processes are linked to elevational richness patterns in ferns: i) limited information on traits and their ecological relevance, ii) uncertainties on the dispersal kernels of ferns and hence the delimitation of regional species pools from which local assemblages are recruited, iii) limited genomic data to identify candidate genes under selection and hence actually document adaptation and selection, and iv) conceptual challenges in developing clear and testable hypotheses to how specific evolutionary processes can be linked to patterns in community composition and species richness.