Genetic structure and male-mediated gene flow in the ghost bat (Macrodermagigas)

The Australian ghost bat is a large, opportunistic carnivorous species that has undergone a marked range contraction toward more mesic, tropical sites over the past century. Comparison of mitochondrial DNA (mtDNA) control reg ion sequences and six nuclear microsatellite loci in 217 ghost bats from ni ne populations across subtropical and tropical Australia revealed strong po pulation subdivision (mtDNA phi(ST) = 0.80; microsatellites URST = 0.337). Low-latitude (tropical) populations had higher heterozygosity and less mark ed phylogeographic structure and lower subdivision among sites within regio ns (within Northern Territory [NT] and within North Queensland [NQ]) than d id populations at higher latitudes (subtropical sites; central Queensland [ CQ]), although sampling of geographically proximal breeding sites is unavoi dably restricted for the latter. Gene flow among populations within each of the northern regions appears to be male biased in that the difference in p opulation subdivision for mtDNA and microsatellites (NT phi(ST) = 0.39, URS T = 0.02; NQ phi(ST) = 0.60, URST = -0.03) is greater than expected from di fferences in the effective population size of haploid versus diploid loci. The high level of population subdivision across the range of the ghost bat contrasts with evidence for high gene flow in other chiropteran species and may be due to narrow physiological tolerances and consequent limited avail ability of roosts for ghost bats, particularly across the subtropical and r elatively arid regions. This observation is consistent with the hypothesis that the contraction of the species' range is associated with late Holocene climate change. The extreme isolation among higher-latitude populations ma y predispose them to additional local extinctions if the processes responsi ble for the range contraction continue to operate.