Twenty-one taxa of rock wallabies presently grouped in 11 species were studied at their type localities and elsewhere. All were chromosomally distinct except for Petrogale xanthopus and P. x. celeris, and all taxa appear to have evolved from an ancestor with a karyotype like that of Thylogale billardierii. The chromosomal structural rearrangements that distinguish the karyotypes of the various taxa of rock wallabies from that of T. billardierii provided a set of derived characters from which a phylogenetic arrangement has been constructed. Chromosome rearrangements that apparently contribute to reproductive isolation were found at hybrid zones between taxa of parapatric distribution. The reproductive capacity of laboratory bred hybrids was assessed in relation to their chromosomal heterozygosity. It is concluded that reproductive isolation in parapatry was sometimes increased by the establishment of different chromosome fusions involving one ancestral chromosome common to both parapatric taxa.

M. pauma, which was formerly thought to be extinct in Australia, has been found in the Great Dividing Range of coastal New South Wales between 29D 28' and 32D 23's. The optimum habitat appears to be areas of wet sclerophyll forest with a thick shrubby understorey in association with grassy areas. Although the species may be locally common, its present status is best defined as rare; it has a limited distribution and normally occurs at a low density throughout its range. Limited data indicate that most young are born between February and June. Two of six females examined were probably in embryonic diapause. Females may mature sexually as early as 12 months old, and at a weight of 2.6-2.8 kg. Adult females in Australia were significantly heavier than those in New Zealand (Kawau I.), and larger in seven external body measurements. In contrast, adult males were significantly larger in Australia than Kawau I. in ear length only. The species is mainly nocturnal and the mean group size is 1.34 animals, i.e. it is usually single individuals that are encountered.

The parma wallaby, Macropus parma, is one of four species of wallaby introduced on to Kawau Island, New Zealand, in ahout 1870. A sample of sixty-four parmas was shot on the island in February 1973 to provide information on breeding activity and age structure of the population. Incidental data were also collected from the tammar wallaby, Macropus eugenii, which is the other common species on the island. Neither the sex ratio of the shot sample of parmas (thirty-seven males to twenty-seven females) nor that of the tammars (eleven males to eleven females) differed significantly from parity. Onset of sexual maturity of female parmas on Kawau I. was delayed when compared with that of captive females. One female was estimated to have bred at 19 months old but most females in the sample were not mature until 2 years old and a few not until 3 years old. In contrast, female tammars became sexually mature at about 12 months. There did not appear to be any delay in the onset of sexual maturity of male parma wallabies. In the shot sample, none of sixteen female parmas capable of having a young were carrying a pouch young whereas nine of ten female tammars had a pouch young. The mean date of birth of these latter young was 30 January (range 18 January - 11 February) which is consistent with the breeding season of tammars in Australia. Among the mature female parmas two had recently mated, six were in pro-oestrus and six were in anoestrus, indicating that the breeding season in 1973 had just commenced. Estimated months of birth for all parmas under 3 years of age suggested that breeding was continuous in 1970–71 but that there had been a defined breeding season in 1972 with births occurring between March and July. There was an excess of 1– and 2–year-old parmas in the sample. This was the result of continuous breeding in 1970–71, presumably due to the provision of pasture on farmland being developed on the island. A sample of thirty-three tammar skulls resulting from a shoot in November 1972 did not show a nmilar excess of 1– and 2–year-old animals as this species has a rigidly defined breeding pattern and the females can produce only one young a year.

Data are presented for growth in length of head, ear, arm, leg, foot, head and body, and tail, and growth in weight of M. parma from birth to maturity. Foot and ear have ceased growing by 2 years of age in both males and females. Growth measured by other parameters has ceased in females by about 3 years of age, but males continue growing in arm length and leg length until about 4.5 years. Adult size is taken as the size of animals 3 years of age and older. The changing relative sizes of the body parts during pouch life are considered. These are discussed in terms of their functional and adaptive significance during development in the pouch. Growth in weight during pouch life can be divided into two phases based upon changes in the instantaneous relative growth rate (k). During the first phase of growth (to about 84 days) k declines rapidly from a mean value of 12.51% per day during the first week to a mean of 2.93% per day for the interval 63-84 days. It is suggested that this phase may represent a continuation of embryonic organogenesis and differentiation. The second phase of growth is a period during which k is constant and extends from about 84 days until almost the end of pouch life. Values of k for individual animals are normally between 2.15% per day and 2.60% per day. This period of growth is considered to be essentially a period of maturation and growth in size of the organ systems developed during the gestation period and first phase of growth. Young first leave the pouch for short periods when they weigh between 7.5 and 10% of the mean adult female weight. They permanently leave the pouch at a mean weight of 21.3% of the adult female value. Comparison with other macropodids indicates an apparent high degree of uniformity in relative sizes of macropodid young at permanent exit from the pouch. Parma young are finally weaned at about 50% of the mean adult female weight. Females raised in captivity reached sexual maturity at about 70% of the adult female weight. Males are larger than females, but sexual dimorphism becomes statistically significant only after males become sexually mature. The forearms of males are shown to be remarkably elongated compared with those of females and it is suggested that this is an adaptation for holding the female during copulation.

Female M. parma in captivity reach sexual maturity at 11 1/2-16 months of age. Scrota1 size indicates that sexual maturity is attained in males at about 22 months. One male had spermatozoa at 19-20 months and another had a first fertile mating at 24-25 months. Mating behaviour is described and resembles that of other small macropodids. M. parma is monovular and polyoestrous. The oestrous cycle has a mean length of 4197810.72 days (n = 58; range 36-59 days) while the gestation period is 34.54*0.13 days (n = 28; range 33-36 days). Post-partum oestrus and mating occurred from 4 to 13 days after birth in a small proportion (16.7%) of those animals examined. However, most animals had an oestrus, while carrying a pouch young, between 45 and 105 days after birth. A few animals did not come into oestrus at all while carrying a pouch young. Removal of pouch young typically resulted in return to oestrus between 6 and 15 days later, in females that had not had a post-partum oestrus or an oestrus while carrying a pouch young. Females which mated at some stage during lactation prior to removal of pouch young gave birth 31.16 days later (n = 3; range 30.5-32.0 days). Three females at the Melbourne Zoo had estimated delayed gestation periods of 31, 31, and 32 days. The earliest observation of a young with its head out of the pouch was at 146 days of pouch life. Most young had left the pouch for short intervals by 175 days with the youngest observed out at 160 days. Young permanently leave the pouch at 211.9+-1.0 days (n = 10; range 207-218 days). Permanent exchange of pouch young has been observed in two cases, both at approximately the time young were first leaving the pouch for short intervals. Some females that mated while carrying a young in the pouch gave birth 6-11 days after permanent pouch exit of the primary young. Unmated females returned to oestrus 12-24 days after permanent pouch exit of their young. Young were weaned at 2 5 3 ) months after pouch exit. Most females entered anoestrus in 1968 following transfer of the animals into small holding pens. In 1969 only 5 of 24 matings resulted in young in the pouch, while in 1970 the corresponding figure was 21 of 44 matings. In both years there was evidence of young being born but apparently being lost during the climb from the urogenital opening to the pouch, probably because of overcrowding of the mothers. Evolution of embryonic diapause is discussed in relation to the reproductive pattern established for M. pavma. It is postulated that embryonic diapause first arose at the end of pouch life and has come to occupy the entire length of pouch life in most macropodids.

Journal Article Ontogeny of Thermoregulation in Macropus parma (Marsupialia, Macropodidae) Get access R. L. Wallis, R. L. Wallis Department of Zoology, Monash University, Clayton, Victoria, Australia, 3168 Search for other works by this author on: Oxford Academic Google Scholar G. M. Maynes G. M. Maynes Department of Zoology, Monash University, Clayton, Victoria, Australia, 3168 Search for other works by this author on: Oxford Academic Google Scholar Journal of Mammalogy, Volume 54, Issue 1, 26 April 1973, Pages 278–281, https://doi.org/10.2307/1378895 Published: 26 April 1973 Article history Accepted: 25 September 1972 Published: 26 April 1973

Pouch young of M. parma were weighed and measured at weekly intervals from birth until shortly after the end of pouch life. Tables giving means and standard deviations of these measurements are provided for estimation of the age of pouch young. The size and shape of the teeth of juvenile and adult animals were studied to facilitate correct identification of the premolar and molar teeth. Vestigial canine teeth were found to be present for a variable period in all juvenile animals studied. Times of eruption of the various teeth were determined for pouch young, juvenile, and young adult animals of known age. Using these data the ages of nine animals from Kawau I., N.Z., were estimated and their subsequent tooth eruption sequences added to the known age sequence. A curve relating age and the molar eruption stage from M 0.2 to M 111.3 is presented for the combined data. The molar teeth appear to be fully erupted at about 5 yr of age, based on extrapolation from the curve. The molar index also shows promise as a means of estimating age. The regression equation : log (age in days) = 2.1912+0.3895 (molar index) is suggested as a working estimate to 3 yr of age.