Islands are ideal systems to model temporal changes in biodiversity and reveal the influence of humans on natural communities.
Although theory predicts biodiversity on islands tends towards an equilibrium value, the recent extinction of large proportions
of island biotas complicates testing this model. The well-preserved subfossil record of Caribbean bats—involving multiple
insular radiations—provides a rare opportunity to model diversity dynamics in an insular community. Here, we reconstruct the
diversity trajectory in noctilionoid bats of the Greater Antilles by applying a dynamic model of colonization, extinction and
speciation to phylogenetic and palaeontological data including all known extinct and extant species. We show species richness
asymptotes to an equilibrium value, a demonstration of natural equilibrium dynamics across an entire community. However,
recent extinctions—many caused by humans—have wiped out nearly a third of island lineages, dragging diversity away from
equilibrium. Using a metric to measure island biodiversity loss, we estimate it will take at least eight million years to regain
pre-human diversity levels. Our integrative approach reveals how anthropogenic extinctions can drastically alter the natural
trajectory of biological communities, resulting in evolutionary disequilibrium.