Comparative phylogenetic analysis of milk output at peak lactation

A large body of literature exists on the comparative aspects of milk nutrient concentrations of numerous species. However, in the last three decades little attention has been given to the comparative aspects of quantitative milk output and the related nutrient outputs at peak lactation, one of the most energy demanding times for the lactating female. Therefore, the purpose of the present study was to investigate milk output, milk energy output (MEO) and milk nutrient outputs in mammals at peak lactation using the phylogenetic generalized least squares approach to account for the potential lack of independence among species. Milk output, MEO and output of milk nutrients (solids, fat, protein and sugar) at peak lactation for 47 mammalian species were evaluated for the present analysis to derive phylogenetically controlled allometric relationships for all species available and separately for species with single young and for species with multiple young. A strong (P < 0.001) positive relationship exists between the response variables (milk output, MEO, milk nutrient outputs) and maternal body mass whether calculated for all mammals or separately for species with single or multiple young. The results revealed that milk output and MEO scaled identically to the power of 0.74 ± 0.05 of maternal body mass and thus confirming the quarter-power scaling exponent for milk output and MEO. For most allometric relationships the phylogenetic signal lambda was intermediate (0 < λ < 1) and thus required phylogenetic correction with the exception for the relationships between milk nutrient outputs and maternal body mass for species with multiple young.

Marsupial and monotreme milk-a review of its nutrient and immune properties

All mammals are characterized by the ability of females to produce milk. Marsupial (metatherian) and monotreme (prototherian) young are born in a highly altricial state and rely on their mother’s milk for the first part of their life. Here we review the role and importance of milk in marsupial and monotreme development. Milk is the primary source of sustenance for young marsupials and monotremes and its composition varies at different stages of development. We applied nutritional geometry techniques to a limited number of species with values available to analyze changes in macronutrient composition of milk at different stages. Macronutrient energy composition of marsupial milk varies between species and changes concentration during the course of lactation. As well as nourishment, marsupial and monotreme milk supplies growth and immune factors. Neonates are unable to mount a specific immune response shortly after birth and therefore rely on immunoglobulins, immunological cells and other immunologically important molecules transferred through milk. Milk is also essential to the development of the maternal-young bond and is achieved through feedback systems and odor preferences in eutherian mammals. However, we have much to learn about the role of milk in marsupial and monotreme mother-young bonding. Further research is warranted in gaining a better understanding of the role of milk as a source of nutrition, developmental factors and immunity, in a broader range of marsupial species, and monotremes.

Habitats modified for tourism affect the movement patterns of an endemic marsupial, the Rottnest Island quokka (Setonix brachyurus)

The quokka (Setonix brachyurus), an iconic marsupial endemic to Western Australia, is listed as vulnerable. It is found at its greatest abundance on Rottnest Island, where little is known about its home range and movement patterns. We estimated the home ranges of 22 male and 23 female quokkas within each season in four habitat types on Rottnest Island: coastal dune, grass/heath, woodland and settlement areas developed for tourism. We also tested for factors affecting home range and space use. The mean seasonal home-range size of quokkas was 1.91 ± 0.23 ha, and there was no effect of sex or weight, habitat type or wet or dry periods on the size of the home ranges. Home-range overlap during both night and day was significantly lower in the settlement (25.9%), compared with costal dunes (78.5%), woodlands (70.3%) and grass/heath (66.6%). This was due to feeding and resting sites being spatially separated, with quokkas resting outside of the settled areas during the day and travelling back to these areas to feed at night. This research demonstrates how tourism development can impact on the behaviour and movement patterns of local species and will inform future management of the quokka on Rottnest Island.

Spatial ecology of the quokka (Setonix brachyurus) in the southern forests of Western Australia: implications for the maintenance, or restoration, of functional metapopulations

We used radio-telemetry to investigate the home-range size and movement patterns of the quokka (Setonix brachyurus) in the southern forests of Western Australia to assess the ability of animals to move between increasingly segregated habitat patches and to identify implications for metapopulation function. We found that quokkas in this region have a much larger home range (71 ± 5.8 ha) and move larger distances (up to 10 km per night) than previously reported for this species in other regions. Temporal and sex variations in home-range size, overlap and movement patterns provided insights into the social structure, reproductive strategies and resource availability for the species in this part of its range. Quokkas moved up to 14 km between habitat patches, where these patches were connected by dense riparian vegetation. While riparian vegetation was used exclusively for movement between habitat patches, quokkas spent only 40% of their time in this ecotype. The current management paradigm of protecting linear riparian vegetation as habitat for quokkas is important for maintaining habitat connectivity, but is unlikely to meet broader habitat and spatial requirements. Management of preferred habitat as well as riparian corridors is necessary for the maintenance of a functional metapopulation.

Fox control and 1080 baiting conundrums: time to prepare for a CRISPR solution

For many years, managing rock-wallaby colonies (Petrogale lateralis lateralis) in the Western Australian Wheatbelt seemed to be a matter of routinely exposing foxes (Vulpes vulpes) to toxic baits (sodium fluoroacetate, 1080®) laid around their rocky outcrops. Recent research has revealed that 1080 baitings are no longer a viable management option. Baiting is flawed over the long term because it does not erase the wallabies’ pervasive fear of being depredated by foxes, which can still make their menacing presence felt before succumbing to poison bait. Accordingly, a ‘landscape of fear’ exists on all rock-wallaby sites, creating a ‘virtual boundary’ beyond which they fear to forage. Severe overgrazing occurs, ultimately causing population crashes, leaving behind devastated outcrops greatly diminished in carrying capacity. The fallout from this scenario produces a management conundrum. Rock-wallaby populations are unstable in the absence of fox control, and conversely, they are also unstable under long-term fox control. Management is now left with few options, and the future of the colonies remains open. Other conundrums involving bait interference and mesopredator release are described. An alternative to 1080 baiting is clearly needed. Recent developments in gene engineering (CRISPR technology) offer a solution in the foreseeable future.