Patterns of genetic diversity within selected subterranean fauna of the Cape Range peninsula, Western Australia: systematic and biogeographic implications

WA Museum Records and Supplements | Updated 9 years ago

Abstract: Detailed and informative systematic frameworks for the species under consideration are an essential prerequisite for any comprehensive biogeographical analysis of the Cape Range peninsula The molecular technique of allozyme electrophoresis has been used to provide such a framework for six separate groups of subterranean fauna occupying the peninsula. The allozyme data are used to assess patterns of genetic diversity within and amongst a troglophilic philosciid isopod, Laevophiloscia yalgoonensis, and five troglobitic groups, the schizomid Draculoides vinei, the paradoxosomatid millipedes Stygiochiropus spp., an undescribed genus of melitid amphipod, Stygiocaris spp. shrimps, and the blind gudgeon Milyeringa veritas. The implications of the data for species delineation, the reconstruction of evolutionary relationships, the estimation of times of divergence, and various aspects of intraspecific diversity are discussed in some detail.

The major outcomes of the study are :- (1) confirmation of the existence of multiple species within the millipedes, amphipods, and shrimps; (2) an indication that additional discrete lineages occur within single morphospecies of millipedes and amphipods; (3) the postulation of a designated sequence of cladogenic events within each troglobitic group; (4) the recognition of three, geographically-based, genetic provinces within both the millipedes and amphipods, but not within the schizomids; (5) the existence of substantial population substructuring within most troglobitic species; (6) the suggestion of "eastern" and "western" components to the fauna occupying the coastal plain, based on the patterns of diversity displayed by the shrimps and the gudgeons; and (7) the suggestion that gene flow is restricted or absent in most of the troglobites. These conclusions all have some relevance to other biogeographic studies outlined in this volume.