Variability and differentiation of microsatellites in the genus Dasyurus and conservation implications for the large Australian carnivorous marsupials

All four species of Australian quolls (Dasyurusspecies) have declined since European settlement in terms of bothrange and population numbers. Six highly polymorphic simplesequence repeats (CAₙ microsatellites) were used to estimate thegenetic variability and population differentiation within andamong twenty populations (including museum specimens from sixpopulations), as a preliminary means of assessing populationconservation status and relative levels of variability withinmembers of the genus. Overall mean expected heterozygosity (HE)and corrected allelic diversity (A′) were highest among westernquolls. Northern quolls, eastern quolls, and tiger quolls werenot significantly different from each other in either measure. There were also significant differences in diversity amongpopulations within species. Genetic differentiation wasestimated by a number of methods and showed that themicrosatellites used here were useful for defining differencesboth among species and populations. Allele frequency data weresummarised by two-dimensional MDS, which was able to partitionpopulations into distinct species clusters. Similarly, theassignment test was able to assign most individuals to both thecorrect species and population levels. Results of MDS and theassignment test may prove useful in forensic applications. Genetic distance and subdivision between pairs of populationswere assessed by two means based on different mutation models formicrosatellites: infinite alleles model (Nei's D, FST) andstepwise mutation model (Goldstein's δ mu;², RST). Pairwisemeasures of population subdivision indicate that most populationsshould be conserved as separate management units. We discussresults of these analyses in terms of applications toconservation for each of the four Australian species of quoll andprovide a genetic basis for future population monitoring in thesespecies.