Historic reveals Anthropocene threat to a tropical urban fruit bat.

Anthropogenic activities have propelled the Earth into a crisis characterized by unprecedented levels of environmental degradation and habitat loss, generating changes in global climatic regimes and initiating the planet's Sixth Extinction Catastrophe [1]. Loss of population genetic diversity is known to be a harbinger of local and global extinction events [2]. However, there is a lack of direct empirical evidence of historic losses of genetic diversity through periods of anthropogenically linked environmental degradation. We present genomic DNA information from a population of Sunda fruit bats (Cynopterus brachyotis) from Singapore, an exceptionally well-studied tropical rainforest island that has undergone substantial environmental degradation and fragmentation through the Anthropocene of the 1930-1950s [3]. As an effective pollinator and seed disperser, C. brachyotis represents an important keystone species in Singapore's ecosystem [4]. Here we show that comparison of historic DNA from individuals collected in 1931 with modern specimens reveals a nearly 30-fold reduction in effective population size and corresponding levels of decline in genetic diversity estimates. Coalescent population models indicate that Singapore's C. brachyotis bats underwent a continuous decline in genetic diversity followed by a stark bottleneck in approximately the 1940s, consistent with the estimated onset of the Anthropocene [5]. C. brachyotis continues to be considered common across Singapore [4], yet our results reveal large-scale impacts of the Anthropocene on biotic communities, even in those species thought to be tolerant to the effects of environmental degradation.