Revisiting global endemism patterns of terrestrial vertebrates and their environmental predictors: putting the focus on species range-restrictions at fine spatial grains

Abstract

Global endemism assessments at fine spatial grains can offer many information about the endemic species richness that inhabit an area, but unable to provide insights on to what extent species distribution ranges are restricted to that area. This inability to account for species range-restrictions prevents recognizing the level of species uniqueness to particular sites, which is necessary to both understand the processes involved in the maintenance of endemism patterns and effectively conserve worldwide biodiversity. To circumvent this problem, the research proposes to use an index capable of measuring the proportion of species restricted to small spatial units. Using species range maps of terrestrial vertebrates, it was assessed global endemism patterns based on species range-restrictions as a counter position to the common use of species richness. Furthermore, it has been evaluated the role that different environmental variables have as predictors of these patterns through simultaneous autoregressive regression. Results showed the highest reported congruence among vertebrate endemism patterns, which suggest the influence of similar processes that affect species range-restrictions through space. Environmental variables explained more than 68% of the total variance on vertebrate endemism, so it is discussed their role as factors that promote species range-restrictions by limiting organism geographic distributions.