Ecoregional Vulnerability Assessment for the Functional Richness of South American Carnivorans (Mammalia: Carnivora)

Abstract

Mapping geographic trends in biodiversity is a key step in conservation planning, which has been mainly focused on taxonomic criteria or species of particular concern. More recently, higher consideration of ecosystem functioning has been advocated, allocating more attention to traits and functional diversity of species assemblages. Carnivorans (Mammalia: Carnivora) are charismatic, albeit threatened, species that variously affect ecosystem functioning through consumptive processes, and whose functional diversity depends on traits associated with their trophic habits and energetic requirements. Yet, analyses of spatial trends in the diversity and vulnerability of carnivoran assemblages have mostly focused on taxonomic and phylogenetic criteria. Then, the present study assessed the vulnerability of the functional richness of South American carnivoran assemblages, both at continental and regional levels. As a first diagnostic of vulnerability, the form of the association between functional richness and species richness (FRS) was assessed through simulations. The resulting nearly linear association indicated low functional redundancy and high sensitivity to global extinctions. A more realistic FRS accounting for actual extinction threats exacerbated losses of functional richness. Further, a positive correlation between effect and response traits suggests non-compensatory responses to environmental stressors by functionally redundant species and, thus, sensitivity of carnivoran functional richness to ongoing trends in land conversion and habitat degradation. Regionally, functional richness paralleled latitudinal gradients in species richness, but vulnerability did not entirely match these variables in space, nor did it risk estimates that accounted for regions’ conservation status. This suggests regional differentiation in conservation priorities, complementing existing taxonomically oriented prioritization schemes.