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In Australia, the genetic integrity of dingoes (Canis lupus dingo) is threatened through hybridisation with feral dogs and consequently the identification of the modern ‘pure’ dingo is ambiguous. There are no accurate classification techniques for dingoes and dingo–dog hybrids in the wild. Genetics, skull morphology and visual assessment are methods currently used, but they often yield contrasting results. We tested skull morphological and visual assessment methods for classifying wild canids in south-eastern New South Wales and examined temporal and geographic trends in skull morphology. Published equations based on discriminant functions revealed varying percentages of dingoes, dogs and their hybrids over time, and did not yield similar results to visual assessment methods. Skull characteristics generally became larger over time but have recently stabilised. Changes in the morphology of the molars were consistent with the occurrence of hybridisation with dogs. Geographic variation was apparent and consistent with Bergmann’s Law, with skulls increasing in size with altitude. This study highlights the importance for improved classification methods of wild canids and the importance of considering geographical variation in morphological studies.
During development the Australian fur seal transitions from a terrestrial, maternally dependent pup to an adult marine predator. Adult seals have adaptations that allow them to voluntarily dive at depth for long periods, including increased bradycardic control, increased myoglobin levels and haematocrit. To establish whether the profile of skeletal muscle also changes in line with the development of diving ability, biopsy samples were collected from the trapezius muscle of pups, juveniles and adults. The proportions of different fibre types and their oxidative capacity were determined. Only oxidative fibre types (Type I and IIa) were identified, with a significant change in proportions from pup to adult. There was no change in oxidative capacity of Type I and IIa fibres between pups and juveniles but there was a two-fold increase between juveniles and adults. Myoglobin expression increased between pups and juveniles, suggesting improved oxygen delivery, but with no increase in oxidative capacity, oxygen utilisation within the muscle may still be limited. Adult muscle had the highest oxidative capacity, suggesting that fibres are able to effectively utilise available oxygen during prolonged dives. Elevated levels of total creatine in the muscles of juveniles may act as an energy buffer when fibres are transitioning from a fast to slow fibre type.
Prior to installation of a fishway at a road crossing in 2001, a remnant population of endangered Macquarie perch (Macquaria australasica) was confined to a 6-km section of the Cotter River, Australian Capital Territory. The purpose of the fishway was to provide passage past a barrier and to increase the extent of spawning grounds for M. australasica to an additional 22 km of river. The aim of the current study was to quantify the extent of nursery grounds of M. australasica in the Cotter River catchment by developing and applying a rapid, non-destructive technique for surveying juvenile M. australasica. From October to January in 2006–07 and 2007–08, pools were surveyed by snorkelling in the lower Cotter River to detect juvenile and larval M. australasica. The 9-km study reach consisted of the four pools immediately upstream of Cotter Reservoir, seven pools further upstream but still downstream of the rockramp fishway and 14 pools upstream of the fishway. In 2006–07, juvenile M. australasica were detected at 22 of 25 pools, including 13 of 14 pools upstream of the fishway. In spring/summer 2007–08, low visibility conditions frequently occurred throughout the river preventing survey on several occasions. However, recruitment of M. australasica was again detected upstream of the fishway. The increased extent of the nursery grounds of this M. australasica population has proven to be timely as an enlargement of the Cotter Reservoir, due for completion in 2012, will inundate more than 90% of prefishway nursery grounds in the Cotter River. Our study has demonstrated the benefit of installing a fishway in expanding the nursery grounds and the number of recruits of a remnant population of the endangered M. australasica. We also demonstrate the benefits of employing a visual survey technique to quantify the extent of the riverine nursery grounds of a fish population.
Structurally generated colours are at least as commonplace and varied components of animal signals as pigment colours, yet we know far less about the former, both in terms of the patterns and phenotypic variation and of their underlying correlates and causes. Many butterflies exhibit bright and iridescent colour signals that arise from a characteristic ‘ridge-lamellar’ scale surface nanoarchitecture. Although there are multiple axes of functional variation in these traits, few have been investigated. Here we present evidence that sexual dimorphism in the expression of a sexually homologous ridge-lamellar trait (iridescent ultraviolet) is mediated by sex differences in the density of lamellar-bearing scale ridges. This trait – ridge density – has also been causally related to iridescent signal variation in other coliadines (e.g. C. eurytheme), which suggests that it may offer a common basis to both intra- and intersexual differences in ultraviolet wing reflectance among these butterflies.
To date there have been only limited fine-scale investigations into the molecular ecology of the European hoverfly, Microdon mutabilis, due to the paucity of available polymorphic markers. We describe the development of primers amplifying five novel microsatellite loci using next-generation sequencing (454) and three previously undescribed M. mutabilis microsatellite loci using enrichments. In hoverflies from a population in Ireland, the number of alleles per locus ranged from 2 to 16, and the observed heterozygosity ranged between 0.26 and 0.97
Reproduction may be influenced by major environmental changes experienced by an entire population as well as variation within a population in maternal resource availability or quality. We examined relationships between body condition and reproductive traits in two wild populations of the seasonally breeding tammar wallaby (Macropus eugenii) on Garden Island, Western Australia, that differed in access to supplemental food resources. Body condition changed predictably over the year, with females losing condition over the dry summer and gaining condition over the winters, when lactation occurs and most annual precipitation falls. Body condition influenced reproduction, with females of greater body condition more likely to have a pouch young, and to have a larger pouch young, early in the reproductive season. This intrapopulation pattern was opposite to that seen across populations – females in a native bushland were in poorer condition yet were more likely to have pouch young, and had larger pouch young, in March than did females living in a water-supplemented habitat on a naval base. Body condition did not influence the probability of weaning a pouch young in a year, nor did reproductive success influence changes in body condition across seasons. Instead, annual variation in precipitation had a dramatic effect on population weaning success in the native bushland, but not on the naval base. In summary, individual variation in body condition as well as large climatic variation influenced the reproduction of tammar wallabies on Garden Island, but the nature of the effect depended on the different habitats experienced by the two study populations.
In many species, male animals produce costly signals to attract females. Intersexual indicator theories propose that these signals are indicative of male quality, whereas individual recognition models are based on the idea that male signals are used primarily to allow for individual discrimination. These two types of models make differing predictions about the nature of male signals. In particular, these models’ predictions differ in the information about a male’s quality that will be included in his signal, the frequency distributions of male signals in a population, and the ways in which the different traits that make up a signal will covary. Calls from the Australian frog Litoria chloris were tested for consistency with the predictions of intersexual indicator models and individual recognition models. The calls were found to contain minimal information on male quality, and the covariance between different signal traits was consistent with the individual recognition models. However, the frequency distributions of male signal traits agreed with intersexual indicator models. In addition, this study found evidence that the information content of calls may instead mediate intrasexual interactions, although more research is required to determine if this is the case.
The endangered Slater’s skink (Liopholis slateri) is restricted to the river floodplain habitat of central Australia. It is an obligate burrower and creates complex, multientrance burrow systems in the mound of soil that builds up around the base of some shrubs and small trees. We provide detailed information about the behaviour and use of the burrow systems by Slater’s skink. The behaviour of lizards remained consistent over the four months (October–January) of the study, and lizards performed almost all of their daily activities around their burrow/mound systems. Lizards also showed signs of sociality, as pairs of lizards were observed to share occupancy of single burrow systems over extended periods, and demonstrated a high level of tolerance to conspecifics. This study emphasises the importance of the burrow systems for the daily life of this lizard and suggests that conservation measures should focus on ensuring that the lizards have a reliable supply of stable and suitable burrows in their preferred habitat.
We isolated 24 novel polymorphic microsatellite markers from the tawny frogmouth, a nocturnal bird endemic to Australia, which has successfully adapted to urban environments. Initially, 454 shotgun sequencing was used to identify 733 loci with primers designed. Of these, we trialled 30 in the target species of which all amplified a product of expected size. Subsequently, all 30 of these loci were screened for variation in 25 individuals, from a single population in Melbourne, Victoria, Australia. Twenty-eight loci were polymorphic with observed heterozygosity ranging from 0.03 to 0.96 (mean 0.58) and the number of alleles per locus ranged from 2 to 18 (average of 6.5); we confirmed that 24 loci conformed to Hardy–Weinberg expectations. The 24 loci identified here will be sufficient to unequivocally identify individuals and will be useful in understanding the reproductive ecology, population genetics and the gene flow amongst localities in urban environments where this bird thrives.
The number of dingo (Canis lupus dingo and hybrids) scats collected from an area has been used as a measure of pack stability in order to make inferences about dingo pack structures and function. In doing so, some studies sampling different sites at different times/seasons have been forced to assume that scat collection rates vary little throughout the year in order to attribute observed site/treatment differences to the effect of interventions (e.g. lethal control), rather than natural spatiotemporal variation in scat densities. In this study, 4112 dingo scats systematically collected from adjacent dingo-baited and unbaited areas at three arid-zone sites on a regular basis over 2–4 years are used to test this assumption. Scat collection rates varied between treatments, sites and surveys, with substantial differences occurring within a few weeks or months. Similar temporal trends between treatments at each site demonstrated that scat collection rates fluctuated independently of dingo control. It was concluded that observations of different scat collection rates between different sites sampled at different times may simply reflect normal spatiotemporal variability in scat densities, which may not reflect absolute dingo abundance.
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