Population-Genetics of the Brushtail Possum Trichosurus-Vulpecula (Marsupialia: Phalangeridae) in Southeastern Australia

Abstract

Electrophoretic analysis of variation at 45 allozyme loci in four populations of common brushtail possums (Trichosurus vulpecula) in southeastern Australia revealed a mean observed heterozygosity of 0.044; 20% of loci were polymorphic. These values are comparable to the amount of allozyme variation found in other marsupials and in eutherians. Heterozygosity was significantly correlated with latitude. Absolute genetic divergence between the four populations was low (Nei's unbiased D of 0.004-0.017), relative to the level of divergence commonly found between populations and subspecies of other mammals. Genetic divergence between Tasmanian and mainland populations was no greater than that found between mainland populations, hence the present subspecific status of the Tasmanian possum, Trichosurus vulpecula fuliginosus, is not supported by genetic data. Relative genetic differentiation among the populations, as measured by the fixation index FST, was 0.145, suggesting that the population structure of possums is comparable to moderately vagile species rather than either highly social or highly vagile species.