Repeated DNA sequences and kangaroo phylogeny.

Three highly repeated DNA sequences have been used to determine relationships of species within the Macropodidae (kangaroos and wallabies). Two highly repeated DNA sequences were isolated as buoyant density satellites in the red-necked wallaby and in the wallaroo-euro group. The third probe was a cloned representative of one class of highly repeated species from the red kangaroo. Radioactively labelled probes of these three repeated sequences were used to determine the incidence and distribution of each in number of macropodid species. The results were consistent with a monophyletic origin of the macropodid species and showed in particular, that the red-necked wallaby is closely related to the red kangaroo and to the euro-wallaroo group. In addition, the data indicated that the tammar and the agile wallaby were closely related. The results also favour the current taxonomic status of the eastern and western grey kangaroos as closely related but separate species.

Karyotypes, constitutive heterochromatin and taxonomy of ringtail opossums of the genus Pseudocheirus (Marsupialia: Petauridae).

Karyotypes are presented for three forms of the common ringtail oppossum, Pseudocheirus peregrinus. These are tentatively regarded as the subspecies P.p. cookii, P.p. pulcher, and P.p. rubidus. In addition, we report for the first time the karyotype of the rock ringtail oppossum, P. dahli. The three forms of P. peregrinus each have a diploid number of 2n=20. C-banding studies indicate that the addition of large blocks of constitutive heterochromatin has played a major role in the evolution of all chromosomes in the karyotype. The X chromosome of P.p. pulcher is metacentic and approximately twice the relative size of the acrocentric X chromosomes of the other two forms of peregrinus. All three forms had two or three pairs of autosomes with secondary constrictions, a rare occurrence within the superfamily Phalangeroidea. P. (Pseudochirops) dahli has a diploid number of 2n=16; a reduction in chromosome number may have occurred by Robertsonian fusions. Four of the eight chromosome pairs lack large blocks of C-band material and the secondary constrictions are located on the sex chromosomes.