Genetic divergence in Heterodoxus octoseriatus (Phthiraptera)

The geographic distributions of alleles at 11 gene loci in Heterodoxus octoseriatus were examined and found not to be random. Rather, there were at least two geographic patterns, one of which mirrored approximately the geographic ranges of the hosts Petrogale p. penicillata and P. p. herberti. Two explanations for the complex geographic arrangement of alleles and the unusually high level of intraspecific variation in H. octoseriatus are considered. Firstly, that populations of H. octoseriatus diverged in allopatry, and that subsequent hybridization of the new taxa led to differential introgression of alleles. Secondly, that H. octoseriatus inhabits heterogeneous environments and that the intraspecific variation is a direct result of natural selection. The likelihood that evidence for divergence followed by hybridization and introgression will be found in other species in the H. octoseriatus group is discussed.