The effects of cultural drift on geographic variation in echolocation calls of the Chinese rufous horseshoe bat ( Rhinolophus sinicus)

Drift, selection, or their combined effects commonly drive geographic variation in traits. Clarifying the relative roles of each process is a long-standing research goal in evolutionary biology. Acoustic signals of bats are a phenotypic characteristic that plays an important role in social organization and species recognition. We extensively sampled the Chinese rufous horseshoe bat (Rhinolophus sinicus) throughout China and Vietnam and reconstructed a species phylogeny to better understand the patterns and causes of the geographic variation of acoustic signals. Our results showed that the resting frequency (RF) of calls varied with latitude, sex, and distance among different colony locations. RF differences were not correlated with genetic distance (based on only one nuclear locus and the mitochondrial locus), climatic factors (mean annual temperature and mean annual precipitable water), or body size, although differences in calls increased with distance among various populations. This suggests that cultural drift may play more important roles than genetic drift and acoustic adaptation in shaping acoustic differences within regions in R. sinicus.