Determinants of zoogeographical boundaries differ between vertebrate groups

Abstract

Aim Worldwide distribution patterns of living animals are structured in multiple zoogeographical regions, characterized by faunas with homogeneous composition that are separated by sharp boundaries. These zoogeographical regions can differ depending on the considered animal group, probably because they have distinct characteristics such as dispersal, metabolism, or evolutionary history, and thus divergent responses to major biogeographical drivers, such as tectonic movements, abrupt climate transitions and orographic barriers. Here, we tested if the drivers of biogeographical boundaries are different between vertebrate classes with strongly divergent traits and evolutionary history. Location Global. Time period Present. Major taxa studied Amphibians, birds and mammals. Methods We focused on terrestrial biogeographical boundaries, considering multiple potential drivers: spatial heterogeneity of present‐day climate, altitudinal variation, long‐term tectonic movements and past climate change (temperature). We used spatially explicit regression models and geographically weighted regressions to select and quantify the factors explaining the position of the biogeographical boundaries between vertebrate classes. Results For mammals, tectonic movements, abrupt climatic transitions and orographic barriers jointly determined extant biogeographical boundaries, with tectonic movements being the most important. For birds, abrupt climatic transitions played the strongest role, while the effect of orographic barriers was weak. For amphibians, biogeographical boundaries mostly corresponded to areas with abrupt climatic transitions. The strongest transitions of amphibian faunas occur in areas with abrupt shifts of temperature and precipitation regimes. Main conclusions Our analyses confirmed that different drivers have jointly shaped the global vertebrate biogeographical regions, and highlight that taxa with different features show heterogeneous responses across the globe. Eco‐physiological constraints likely increase the importance of spatial heterogeneity of climate, while dispersal limitations magnify the relevance of physical barriers (mountain chains and long‐term tectonic instability). Integrating among‐taxa heterogeneity into analyses thus provides a more complete view of how different processes determine biodiversity variation across the globe.

Key roles for the freezing line and disturbance in driving the low plant species richness of temperate regions

“…Cluster analyses have been widely used to identify patterns in the co-distribution of species (Antonelli, 2017;Ficetola et al, 2021;Holt et al, 2013;White et al, 2019White et al, , 2021. It has long been known that there are distinctive faunas and floras, termed biotas, present in different regions (Antonelli, 2017;Holt et al, 2013).…”

“…It has long been known that there are distinctive faunas and floras, termed biotas, present in different regions (Antonelli, 2017;Holt et al, 2013). Recent work has moved from documentation of the pattern towards identifying the historical processes, geographical barriers, and climatic conditions that limit whole collections of species to specific regions (Ficetola et al, 2017(Ficetola et al, , 2021Segovia et al, 2020) and to identifying the degree to which turnover between realms (the region occupied by a biota) is sharp (White et al, 2019(White et al, , 2021). An emergent finding has been that climatic factors (precipitation and temperature) importantly organize realms, demonstrated across groups as disparate as amphibians, birds, mammals and trees (Ficetola et al, 2021;Segovia et al, 2020).…”

Population demography maintains biogeographic boundaries

“…The spatial organization of global biodiversity results from complex, interacting processes (e.g., historical, evolutionary, ecological) acting over time to shape the biogeographic patterns we observe today. In mammals, biogeographic boundaries are related to tectonic plate movements, and these boundaries are associated with deeper divergences in the phylogenetic relatedness of mammal assemblages across regions (Ficetola et al 2017(Ficetola et al , 2021. Climate and elevation have also likely continuously affected dispersal and population demography over long periods to shape regional species assemblages (Ficetola et al 2021).…”

“…In mammals, biogeographic boundaries are related to tectonic plate movements, and these boundaries are associated with deeper divergences in the phylogenetic relatedness of mammal assemblages across regions (Ficetola et al 2017(Ficetola et al , 2021. Climate and elevation have also likely continuously affected dispersal and population demography over long periods to shape regional species assemblages (Ficetola et al 2021). These historical and contemporary processes have created biogeographic patterns that are, as our results suggest, partly formed by local microevolutionary population processes limiting population spread.…”

Conservation hotspots of insular endemic mammalian diversity at risk of extinction across a multidimensional approach

“…Nevertheless, as insular regions with the biggest areas and harboring the highest diversity values were not necessarily identified as hotspots, area did not seem to be a good predictor for a high endemic mammal diversity in some insular regions. Diversity can be related to environmental and latitudinal conditions but also to geological histories, biogeographical processes and spatial structure of islands (Ficetola et al, 2021; Whittaker & Fernandez‐Palacios, 2007; Willig & Presley, 2018). For instance, Kalmar and Currie (2006) found that 87% of the global variation in non‐marine bird species richness among worldwide islands was related not only to island size but also to climate and island isolation.…”