Mitochondrial DNA variation among populations of Oedura reticulata (Gekkonidae) in remnant vegetation: implications for metapopulation structure and population decline

Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA was used to examine the regional population structure of a species of gecko (Oedura reticulata) in vegetation remnants within the Western Australian wheatbelt. The species exhibited considerable polymorphism within and between populations with 22 haplotypes recognized among 12 populations. Phylogenetic analysis of haplotypes and clustering of nucleotide divergence among populations demonstrated little regional structure within the species with several haplotypes present in all three regions surveyed. This contrasted markedly with variation in haplotype frequency among populations which showed a high degree of independence between populations indicating that current levels of maternal gene flow are low and that the populations are too small to prevent genetic drift. This conclusion is supported by generally lower numbers of haplotypes in remnant populations than in nearby nature reserves. These findings, combined with demographic data from a previous study, suggest that post-fragmentation populations of O. reticulata are unable to form a metapopulation structure in the habitat that remains and that stochastic extinction forces alone will be sufficient to severely reduce the regional distribution of this species. This study demonstrates that mtDNA is a useful tool for detecting contemporary population phenomena and can provide qualitative information of practical importance to wildlife managers.