MITOCHONDRIAL-DNA ANALYSIS OF INTROGRESSION BETWEEN ADJACENT TAXA OF ROCK-WALLABIES, PETROGALE SPECIES (MARSUPIALIA, MACROPODIDAE)

Simple, inexpensive techniques were used to analyse the mtDNA of nine chromosomally distinct populations of Petrogale. Eight of these populations occur in sequence along the Great Dividing Range of eastern Australia; six have been described as species. Diagnostic mtDNA morphs were found throughout the latitudinal ranges of four of the described species. A fifth morph spanned the ranges of two described species and three additional taxa which have been designated chromosome races. These five mtDNA morphs, and others with local distributions, were used to assess interactions between the taxa. Limited introgression was indicated across the chromosomal boundaries of P. penicillata/P. herberti and P. inornata/P. assimilis; atypical mtDNA morphs were found within the P. herberti and P. inornata chromosomal distributions. No introgression was detected between P. herberti and P. inornata, whose distributions are separated by the Fitzroy River. Nor was there evidence of recent contact between P. assimilis, P. herberti and P. purpureicollis, despite the late occupancy of parts of the intervening area by unidentified Petrogale. These data, considered in the light of information obtained from previous studies on chromosomes, allozymes and parasites, have contributed to the decision to consider all the eastern representatives of the lateralis-penicillata group of Petrogale as being specifically distinct from each other.