Mobility of Australian flying-foxes, Pteropus spp. (Megachiroptera): evidence from genetic variation.

Black (Pteropus alecto) and grey-headed (Pteropus poliocephalus) flying-foxes inhabit large ranges in coastal north and eastern Australia. P. poliocephalus is endemic to region and is classified as vulnerable. The bats are known to migrate in response to flowering and fruiting of their food plants, but direct observation of movement patterns is difficult. Protein electrophoresis was used to investigate genetic subdivision among populations. High gene flow was inferred for both species with an estimated exchange of 15 (P. alecto) and 28 (P. poliocephalus) individuals between populations per generation. Wright's FST, an index of among population genetic variation, was low, 0.023 (P. alecto), 0.014 (P. poliocephalus), reflecting the homogenising action of movements across the species' ranges. An FST value of 0.028 has been reported for a third Australian species, the little red flying-fox, P. scapulatus. The FST values for Australian flying-foxes are closer to those found for birds than the typically higher values for mammals and we conclude that these flying-foxes are essentially panmictic and for management purposes should be treated as migratory species.