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Despite a large body of research, little agreement has been reached on the ultimate driver(s) of geographic variation in body size (mass and/or length). Here we use skull length measurements (as a surrogate for body mass) from five Australian marsupial species to test the primary hypotheses of geographic variation in body size (relating to ambient temperature, productivity, and seasonality). We used a revised articulation of Bergmann’s rule, wherein evidence for thermoregulation (heat dissipation or heat conservation) is considered supportive of Bergmann’s rule. We modeled the skull lengths of four Petaurid glider species and the common brushtail possum (Trichosurus vulpecula) as a function of indices of ambient temperature, productivity, and seasonality. The skull length of Petaurus ariel, P. notatus, and the squirrel glider (P. norfolcensis), increased with increasing winter minimum temperature, while that of T. vulpeculadecreased with increasing summer maximum temperature. The skull length of P. arieldecreased with indices of productivity, falsifying the productivity hypothesis. Only P. arielmet the hypothesis of seasonality, as skull length increased with increasing seasonality. Thermoregulation was the most consistently supported driver of geographic variation in body size, as we found evidence of either heat conservation or heat dissipation in four of the five species examined. We found the geographic range of the individual species and the climate space in which the species occurred was integral to understanding the species’ responses to climate variables. Future studies should use specimens that are representative of a species’ entire geographic range, encompass a variety of climatic regions, and use consistent methodologies and terminology when testing drivers of geographic variation in body size.

Subspecific status has often been used as a surrogate for conservation unit, but does not always reflect intraspecific lineages with different evolutionary histories. One contentious case of subspecific classification occurs in the yellow-bellied glider (Petaurus australis), a marsupial species showing considerable decline in population size and requiring conservation management. Our aim was to assess the current subspecific status of populations and define units of conservation using a combination of phylogeographical analyses of mitochondrial DNA and morphological analyses. Analyses of the mitochondrial ND4 gene provided evidence for significant phylogeographic structure within P. australis. Isolated populations in north Queensland (NQ) and Victoria/South Australia were genetically distinct from populations in New South Wales and southern Queensland. Morphological analyses provided little evidence for discrimination of populations, although NQ specimens were generally smaller in size than southern forms. Our analyses do not support the classification of subspecies P. a. reginae for the original type specimen from southern Queensland. Taking into account other behavioural and ecological data, and the disjunct distribution of NQ populations from southern populations, we propose that the NQ population represents a distinct Evolutionarily Significant Unit, a lineage showing highly restricted gene flow from the rest of the species.

This study provides the first assessment of the diet of the yellow-bellied glider (Petaurus australis) in the south-west portion of its range near the Victorian–South Australian border. Examining its diet in this region is viewed as being fundamental to understanding the ecological requirements of the species. Observations were conducted over a five-year period on gliders from five distinct groups. Sap was the most important food item throughout the year and accounted for 83% of 407 feeding observations. Each group of gliders used up to 21 different trees for sap, but during any sample period only 1–8 trees were used. This represents a vastly different pattern of use of sap trees to that described in any earlier study. Some trees were visited more often than others, and these tended to be heavily scarred, indicating use over many years. Other food types were arthropods and honeydew and, to a lesser extent, nectar. This study also revealed that the yellow- bellied glider is not dependent on a diversity of tree species nor on a winter-flowering species. We provide a review of the diet of the yellow-bellied glider throughout its range. This shows that the yellow-bellied glider is reliant on sap as a food resource but particularly so at both ends of its geographic range. The reason for this is unclear, but there is definitely a need for further study of sap-flow patterns in eucalypts.

Fruit set is consistently low in the genus Banksia(Proteaceae). One explanation for low fruit:flower ratios is that excess flowers allow plants to selectively abort inferior progeny thereby increasing the average quality of the seed crop. We examined whether self-pollinated fruits were aborted selectively in a partially self-compatible population of Banksia spinulosa.Inflorescences were divided in half and pollinated with cross pollen on both sides, self pollen on both sides or cross pollen on one side and self pollen on the other. Seed production was reduced significantly by 38% on fully self-pollinated compared to fully cross-pollinated inflorescences, indicating partial self-incompatibility or inbreeding depression. On inflorescences pollinated with both cross and self pollen, selfed seed set was reduced by 63% compared to crossed seed set. On the selfed half of these inflorescences, fewer fruits and seeds were produced, and more fruits had aborted seeds than on randomly selected halves of fully self-pollinated inflorescences. These results suggest that self-fertilized embryos were developed in the absence of outcrossed progeny but were selectively aborted when outcrossed progeny were present on inflorescences. To determine the amount of outcrossing occurring in the study population, outcrossing rates (t) of naturally pollinated plants were examined by electrophoretic assessment of progeny arrays. Values of tdid not differ significantly from one, indicating complete outcrossing. High outcrossing, despite the high probability of self pollen receipt under natural conditions, is consistent with the conclusion that selective abortion occurs in B. spinulosa.

This study investigated the genetic structure of a population of the highly outcrossed perennial shrub, Banksia spinulosa. Three variable loci were detected; Pgm1, Adh1and Pgi2. Some genetic differentiation was detected in the population, and as a whole it deviated from a panmictic unit. This primarily resulted from the behaviour of Pgi2. This locus exhibited a large deficit of heterozygotes, possibly in association with a Wahlund effect. However, deviations from panmixia were small compared with species which are predominantly self-fertilizing, and estimates of gene flow indicated that the movement of genes occurs over a fairly wide area. This study provides the first description of spatial genetic variability within a population of Banksia spinulosa.Heredity (1993) 70, 566–573; doi:10.1038/hdy.1993.83

Improving our understanding of resources required by threatened small mammals is directly relevant to the success of habitat restoration and species reintroduction programs. In a case study based on southern brown bandicoots (Isoodon obesulus obesulus; Mammalia: Peramelidae) occupying a remnant of open forest with a sclerophyllous shrub understory, we investigated microhabitat composition using multivariate analysis, and disproportional use of these habitats using a variety of techniques, including principal canonical correlation vectors, chi-square test, compositional analysis (CA), and nonparametric multiplicative regression. Spool-and-line tracking of bandicoots enabled floristic and structural parameters to be recorded from sites of activity and compared with sites randomly located within 5-ha grids centered over each trapping transect. Each of the 4 methods applied contributed useful interrogation of the potential resources required by I. o. obesulus, with most disproportional use of microhabitats across activities detected using CA. Analyses supported fine-scale preference for Xanthorrhoea semiplana-dommaicd microhabitat across all activities, nesting in Banksia ornata-dominated microhabitat, moving and foraging in Allocasuarina muelleriana subsp. muelleriana microhabitat, impartial use of and increased reliance on burrows for shelter in Eucalyptus cosmophylla open forest with Melaleuca decussata understory microhabitats, and avoidance of Cyperaceae-dominated microhabitat and mixed heath. These results show that within broadly suitable vegetation communities, I. o. obesulus differentially utilizes a mosaic of microhabitats for a range of activities associated with shelter and foraging. Hence, the success of reintroduction and habitat restoration programs may be improved by considering the availability of preferred microhabitats (or alternative structures in suboptimal habitats, e.g., burrows), and protecting or revegetating indicator and associated species of known preferred microhabitats, respectively.

This study provides the first assessment of the diet of the yellow-bellied glider (Petaurus australis) in the south-west portion of its range near the Victorian–South Australian border. Examining its diet in this region is viewed as being fundamental to understanding the ecological requirements of the species. Observations were conducted over a five-year period on gliders from five distinct groups. Sap was the most important food item throughout the year and accounted for 83% of 407 feeding observations. Each group of gliders used up to 21 different trees for sap, but during any sample period only 1–8 trees were used. This represents a vastly different pattern of use of sap trees to that described in any earlier study. Some trees were visited more often than others, and these tended to be heavily scarred, indicating use over many years. Other food types were arthropods and honeydew and, to a lesser extent, nectar. This study also revealed that the yellow- bellied glider is not dependent on a diversity of tree species nor on a winter-flowering species. We provide a review of the diet of the yellow-bellied glider throughout its range. This shows that the yellow-bellied glider is reliant on sap as a food resource but particularly so at both ends of its geographic range. The reason for this is unclear, but there is definitely a need for further study of sap-flow patterns in eucalypts.