Functional niche constraints on carnivore assemblages (Mammalia: Carnivora) in the Americas: What facilitates coexistence through space and time?

Abstract

Aim Mammalian carnivores are among the best studied groups in terms of evolutionary history. However, the effects of species interactions in shaping community assemblages remain poorly understood. We hypothesize that indirect interactions via ecological trait filtering play a key role in structuring carnivoran assemblages, mediate coexistence and thus should show high functional diversity (FD) in space and time at continental scales. Location The Americas. Taxon Mammalian carnivores (Mammalia: Carnivora). Methods We followed a macroecological perspective via ecological network analyses for indirect interactions and assessed the underlying FD across space and from the last interglacial to the present in the Americas. We analysed the potential distributions and six ecological traits of 88 species to establish possible mechanisms that enables species to coexist and the underlying diversity patterns. We compared the empirical results with two null models and two sensitivity analyses. Results Co‐occurring carnivore species presented ecological segregation driven mainly by a size ratio ( S R ) relationship, called here the body size spatial anti‐clustering effect. The underlying FD patterns showed low redundancy towards the tropics and the poles during the times evaluated. However, during the last glacial maximum, shifts occurred primarily at high latitudes in North America. This shift affected the S R relationship and therefore changed FD patterns. These local‐to‐continental interactions mediated by the S R are significant from an ecological and biogeographic perspective, suggesting a robust and consistent trend in which carnivore species of similar size have a lower probability of occupying the same area unless they differentiate in other ecological trait spaces. Main conclusions The S R relationship is potentially a primary mechanism limiting carnivore coexistence, reflecting functional filtering. The S R tends to be conservative across different ecological trait groups and through time and space. We propose that the body‐size spatial anti‐clustering effect can directly measure species' coexistence and mediate FD patterns in the Americas.

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