Strong matrilineal structure in common pipistrelle bats (Pipistrellus pipistrellus) is associated with variability in echolocation calls

The ontogeny and heritability of echolocation, an important sense in echolocating bats, is still not completely understood. Intraspecific variation in echolocation calls can be high, although the importance of possible explanatory variables (e.g. age, sex, social groups) remains largely unknown. Echolocation pulse features may vary among maternity roosts and this can theoretically be caused either by intercolony genetic differences or by vocal dialects learned during ontogeny within a roost (or a combination of both). In the present study, we analyzed intraspecific variation in echolocation parameters in relation to genetic structure at bi-parentally inherited microsatellites and maternally inherited mitochondrial (mt)DNA in maternal colonies of Pipistrellus pipistrellus in Central Europe. We found that individual colonies differ significantly in mtDNA, whereas the structure on nuclear markers is almost absent. This suggests a typical temperate bat social structure pattern, with strong sex-biased dispersal (i.e. philopatric females and dispersing males) (up to 92% of males leave their birth place according to our results). However, we show for the first time that genetic differentiation among mtDNA matrilines is associated with significant intercolony echolocation parameter differences. Because the genetic component of echolocation is not likely to be encoded by mtDNA, the results support the hypothesis of maternal echolocation dialect transmission to offspring, and the role of learning in this process is discussed.