Sex-biased dispersal in a migratory bat: A characterization using sex-specific demographic parameters

We studied the noctule bat (Nyctalus noctula), in which the mitochondrial F -ST is about 10 times that revealed by nuclear markers, to address two ques tions. We first verified whether random dispersal of one sex is compatible with highly contrasted mitochondrial and nuclear population structures. Usi ng computer simulations, we then assessed the power of multilocus populatio n differentiation tests when the expected population structure departs only slightly from panmixia. Using an island model with sex-specific demographi c parameters, we found that random male dispersal is consistent with the po pulation structure observed in the noctule. However, other parameter combin ations are also compatible with the data. We computed the minimum sex bias in dispersal (at least 69% of the dispersing individuals are males), a resu lt that would not be available if we had used more classical population gen etic models. The power of multilocus population differentiation tests was u nexpectedly high, the tests bring significant in almost 100% of the replica tes, although the observed population structure infered from nuclear marker s was extremely low (F-ST = 0.6%).