Genetic Impoverishment in the Anthropocene: A Tale from Bats

Abstract

Habitat loss, fragmentation, and anthropogenic climate change are major drivers of biodiversity declines during the ongoing Anthropocene epoch. Understanding the evolutionary trajectories of organisms with diverse life histories in response to these threats can enable us to predict the fate of the extant biota facing accelerated habitat loss and climate change. Genetic data contain vital clues about species diversity and have been widely used to assess the impacts of non-anthropogenic climate change (since the Last Glacial Maximum and during the Holocene) on a range of species. Recent advances in sequencing technologies and analytical approaches have broadened the scope of genetic investigations. They have allowed us to directly test for recent population bottlenecks linked to rapid, anthropogenic environmental change. In this chapter, we discuss the utility of genomic data in identifying evolutionary trajectories of bats in response to climate change and habitat modification. We show that these nocturnal mammals are particularly sensitive to environmental and habitat fluctuations. We also summarise and discuss our recent investigations of an urban population of the lesser short-nosed fruit bat (Cynopterus brachyotis) from the island nation of Singapore and assess the response of this population to rapid urbanisation during the Anthropocene. Comparisons of genetic diversity estimates and evolutionary models through coalescent simulations revealed that this local population had been on a slow decline for centuries but faced a more drastic bottleneck a few decades ago. We also observed an astonishing level of decline in indicators of genetic diversity in the local population over the past century, coinciding with the rapid urbanisation of Singapore. Our observations show that even commonly occurring, synanthropic species of bat (i.e. lives within and appears to benefit from urban environments) have been negatively impacted by rapid urbanisation. Our results also highlight the necessity of assessing the impact of urban green spaces on the evolution and survival of organisms like bats, which often rely on these remnant habitats.