The Geography of Ecological Niche Evolution in Mammals

Abstract

SummaryConvergent adaptive evolution of species' ecological niches -i.e. the appearance of similar niches in independent lineages-is the result of natural selection acting on niche-related species traits ('traits' hereafter) and contrasts with neutral evolution [1][2][3][4]. While trait convergences are recognized as being of importance at the species scale, we still know little about the impact of species convergence on the overall trait and niche structure of entire biotas at large spatial scales [5]. Here, we map the convergent evolution of four traits (diet, body-mass, activity cycle and foraging strata) for mammal species and assemblages (defined at 200x200km resolution) at a global scale. Using data on the geographic distributions, traits, and phylogenetic relationships of species and by comparing observed patterns of trait β-diversity to evolutionary neutral expectations, we show that trait convergence is not restricted to particular lineages, but scales up to entire assemblages (i.e. whole species communities). We find region-wide biota convergence in traits between regions with similar climates, particularly between Australia and other continents.Corresponding author (and lead author): Mazel, Florent, flo.mazel@gmail.com. The authors declare no conflicts of interest. Author contributionsJR formatted the distribution data. FM conceived the study, with advices from SL, ROW and WT. FM performed all analyses, with help of ROW and MG. FM interpreted the results with help of ROW, GFF, SL and WT. FM & WT wrote the first version of the manuscript and all authors contributed to revisions. Pairs of assemblages that show trait divergence often involve arctic regions where rapid evolutionary changes occurred in response to extreme climatic constraints. By integrating both macro-ecological and macro-evolutionary approaches into a single framework, our study quantifies the crucial role of evolutionary processes such as natural selection in the spatial distribution and structure of large-scale species assemblages. Europe PMC Funders Group KeywordsCommunity convergence; Community divergence; Marsupials; trait beta-diversity; functional betadiversity; neutral evolution; Brownian motion Results and DiscussionConvergent evolution caused by natural selection occurs when independent lineages that experience the same environmental constraints evolve similar morphological, physiological and/or behavioural traits [1,4], ultimately leading them to occupy similar ecological niches. Parallelism, where similar trait changes occur in closely-related ancestors, is sometimes distinguished from convergence because it usually occurs at a smaller phylogenetic scale. However, parallelism and convergence are part of a continuum, hampering any clear distinction among them [1,4], thus, we use the term convergence for all phylogenetic scales (as proposed by ref [4], 'parallelism' should be restricted to characterize the degree of molecular similarities underlying phenotypic convergences). Convergent evolution leads to higher ecological niche...

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