Expanding the understanding of local community assembly in adaptive radiations

Stefan Lötters,Katharina C Wollenberg,Michael Veith

doi:10.1002/ece3.908

Stefan Lötters, Katharina C Wollenberg + Show 1 more

Open Access

https://doi.org/10.1002/ece3.908

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Abstract

Communities are thought to be assembled by two types of filters: by the environment relating to the fundamental niche and by biotic interactions relating to the realized niche. Both filters include parameters related to functional traits and their variation along environmental gradients. Here, we infer the general importance of environmental filtering of a functional trait determining local community assembly within insular adaptive radiations on the example of Caribbean Anolis lizards. We constructed maps for the probability of presence of Anolis ecomorphs (ecology-morphology-behavior specialists) on the Greater Antilles and overlaid these to estimate ecomorph community completeness (ECC) over the landscape. We then tested for differences in environmental parameter spaces among islands for real and cross-fitted ECC values to see whether the underlying assembly filters are deterministic (i.e., similar among islands). We then compared information-theoretic models of climatic and landscape parameters among Greater Antillean islands and inferred whether body mass as functional trait determines ECC. We found areas with high ECC to be strongly correlated with environmental filters, partly related to elevation. The environmental parameters influencing high ECC differed among islands. With the exception of the Jamaican twig ecomorph (which we suspect to be misclassified), smaller ecomorphs were more restricted to higher elevations than larger ones which might reflect filtering on the basis of differential physiological restrictions of ecomorphs. Our results in Anolis show that local community assembly within adaptive island radiations of animals can be determined by environmental filtering of functional traits, independently from species composition and realized environmental niche space.

Highlights

The idea that community assembly is largely competitionbased (Diamond 1975; Adams 2007) today is relativized by the identification of additional determining factors
Our results in Anolis show that local community assembly within adaptive island radiations of animals can be determined by environmental filtering of functional traits, independently from species composition and realized environmental niche space
We found ecomorph community completeness (ECC) values on Hispaniola, Cuba, and Puerto Rico to almost perfectly correspond to the topographical map of the Greater Antilles, with an additional area of high ECC on the north-western tip of Cuba

Summary

Introduction

The idea that community assembly is largely competitionbased (Diamond 1975; Adams 2007) today is relativized by the identification of additional determining factors. Community assembly is thought of being determined by two types of filters: by the environment relating to the fundamental niche and by biotic interactions relating to the realized niche (Weiher et al 2011). Both filters act upon functional traits and their variation along environmental gradients (Uriarte et al 2010; Weiher et al 2011). Convergence of community functional traits across similar climatic parameters has, for example, been identified in South American tropical forests (Kraft et al 2008), stream fishes of Europe and North America (Lamouroux et al 2002), and bat assemblages across latitudinal gradients (Stevens et al 2003), which suggests that niche-based assembly might be the norm (Garnier et al 2007; Weiher et al 2011)

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