Robert L. Close

Chromosomal rearrangements in rock wallabies, Petrogale (Marsupialia: Macropodidae)

Chromosomal rearrangements in the two currently recognised races of Petrogale godmani were examined using C- and G-banding. The nominate race P. godmani godmani (2n = 20) was found to possess an inverted chromosome 5 and an acrocentric 6-10 fusion, which can be derived from a 6-10 centric fusion by a centromeric transposition. The Cape York race (2n = 22) was found to retain the ancestral submetacentric chromosome 4 and the ancestral chromosome 5. Thus despite their genic similarity, the two races clearly have major chromosomal differences and should be regarded as separate species. Petrogale g. godmani shares two derived chromosomes with another Queensland taxon, the assimilis race of P. assimilis, indicating recent common ancestry. The Cape York race retains characteristics of an ancestral stock of Petrogale and its genic similarity with P. g. godmani could therefore be the result of extensive introgression.

Taxonomy of rock-wallabies, Petrogale (Marsupialia : Macropodidae). III. Molecular data confirms the species status of the purple-necked rock-wallaby (Petrogale purpureicollis Le Souef)

Mitochondrial DNA (mtDNA) analysis was undertaken to resolve the systematic uncertainties surrounding the morphologically distinct purple-necked rock-wallaby (P. lateralis purpureicollis) of north-west Queensland, Australia. A comparison of mtDNA sequence divergence using both whole mtDNA restriction site and control-region sequence analyses revealed that P. l. purpureicollis was as well differentiated from other P. lateralis (black-footed rock-wallaby) taxa as P. lateralis was from P. penicillata (brush-tailed rock-wallaby) or P. assimilis (allied rock-wallaby). Phylogenetic analysis of the sequence data suggests thatP. lateralis (sensu lato) is paraphyletic, with P. l. purpureicollis being more closely aligned to P. penicillataand P. assimilis than to P. lateralis (sensu stricto). Data are also presented that demonstrate significant differences in the distribution of the telomeric repeat sequence (TTAGGG)n between the chromosomes of P. l. purpureicollis and the karyotypically similar MacDonnell Ranges race of P. lateralis. In addition, meiosis appears to be severely disrupted in the majority (73%) of oocytes examined from two P. l. purpureicollis MacDonnell Ranges race hybrids. In light of these findings we recommend that the purple-necked rock-wallaby be reinstated as a full species, P. purpureicollis Le Souef 1924.

Zoogeography and host associations of the Heterodoxus octoseriatus group and H. ampullatus (Phthiraptera : BoopIIdae) from Rock-Wallabies (Marsupialia : Petrogale)

Species of the Heterodoxus octoseriatus group infest five species, comprising eight chromosome races, of Petrogale in Queensland and northern New South Wales, Australia. The precise host and geographic ranges of the 11 species of the H. octoseriatus group were determined. Individual hosts and host populations were infested by single species of lice only. The geographic ranges of lice were discrete. In some cases the geographic ranges of louse species and their hosts were approximately congruent. In others they were completely incongruent and it was unclear which species originally infested which hosts or even which was the most recent colonizer. In at least one case, expansion of the geographic range of one species of louse apparently led to fragmentation of the range of another and subsequently, to allopatric speciation.

Host-parasite associations of Eimeria spp. (Apicomplexa: Eimeriidae) in rock wallabies, Petrogale spp. (Marsupialia: Macropodidae)

Seven new species of Eimeria are described from oocysts present in the faeces of nine species of rock wallabies (Petrogale spp.) The distribution of Eimeria spp. by host coincided in many cases with species groups of rock wallabies defined in other studies. E. sharmani new species was found in all members of the lateralis-penicillata species group: 1445P. assimilis, 724P. godmani, 314P. inornata, 1020P. penicillata, 418P. lateralis and 16P. rothschildi. E. petrogale new species was found in 40 P. assimilis, 15 P. godmani, 12 P. inornata, 19 P. penicillata, 2 P. lateralis, and from 13P. persephone. E. boonderooensis new species was found in 12 P. assimilis and 7 P. inornata; E. godmani new species in 3 P. godmani and 1 P. assimilis; E. inornata new species in 1 P. inornata and 1 P. penicillata ; and an unnamed coccidian in 1 P. penicillata. E. occidentalis new species was present in 2 P. lateralis, 2 P. rothschildi, and in 28P. brachyotis, of the cytogenetically distinct brachyotis species group. E. xanthopus new species was found only in 67P. xanthopus. the principal member of the third species group. Where an Eimeria species is found in rock wallabies of more than one species group, the hosts have geographically contiguous ranges. A character Wagner tree, illustrating relationships among the host species computed on the basis of host-parasite associations, corresponds closely with phylogenies suggested on the basis of cytogenetic and isoenzyme studies.

Phylogeny inferred from allozymes in the Heterodoxus octoseriatus group of species (Phthiraptera : Boopiidae)

Phenetic and phylogenetic relationships in the Heterodoxus octoseriatus group of species were explored with data from 21 putative allozyme loci. The phenetic analyses and some of the cladistic analyses (maximum parsimony) were consistent with a phenetic analysis of morphological characters in that they indicated two main lines of evolution in the H. octoseriatus group. These culminated in two groups of species: (i) H. harrisoni, H. hughendensis, H. closei, H. maynesi, H. octoseriatus, H. lesouefi, H. briscoei and H. insulatus, and (ii) H. murrayi, H. insularis and H. orarius. The allozyme and morphological analyses, however, differed in the arrangement of species within the two main groups. Other cladistic analyses revealed the first group of lice, but not the second group. A hypothesis proposed for the evolution of the H. octoseriatus group involves widespread host-switching followed by the expansion of the geographic ranges of some lice at the expense of others. The evolution of host-parasite associations among rock-wallabies and lice from the H. octoseriatus group demonstrates how tangled the history of host-parasite associations may become.

Genetic divergence in Heterodoxus octoseriatus (Phthiraptera)

The geographic distributions of alleles at 11 gene loci in Heterodoxus octoseriatus were examined and found not to be random. Rather, there were at least two geographic patterns, one of which mirrored approximately the geographic ranges of the hosts Petrogale p. penicillata and P. p. herberti. Two explanations for the complex geographic arrangement of alleles and the unusually high level of intraspecific variation in H. octoseriatus are considered. Firstly, that populations of H. octoseriatus diverged in allopatry, and that subsequent hybridization of the new taxa led to differential introgression of alleles. Secondly, that H. octoseriatus inhabits heterogeneous environments and that the intraspecific variation is a direct result of natural selection. The likelihood that evidence for divergence followed by hybridization and introgression will be found in other species in the H. octoseriatus group is discussed.