Meeting Abstract
Humans have played a significant role in the biology of planetary species extinctions from the Pleistocene to the present. Despite the diverse causes of these human-associated extinctions, extinction patterns are not random. Recent studies have shown that extinction risk may be linked to specific life history or ecological traits that make a species inherently susceptible to human activities. How this relationship may have changed over the course of human history, however, is not well known. Here, we examined how human-associated mammalian extinctions at different trophic levels vary from the end of the Pleistocene to present day. To execute these comparisons, we grouped species into trophic levels, assigned them a threat assessment, and used random simulations to investigate whether extinction risk patterns in trophic levels over time deviated from null model predictions. We found that, overall, herbivores were consistently overrepresented in mammalian extinctions, but that the proportion of extinct or threatened herbivores declined over time. Of the Pleistocene extinct species, more herbivores and fewer predators and omnivores went extinct than predicted in the null model. This general pattern persisted in analyses of mammalian species that have recently gone extinct and that are presently threatened by extinction. The percent of extinction prone herbivores has declined over time, suggesting human impacts may be more equally spread across trophic levels in present time.
