Human landscape modification is amongst the greatest drivers of biodiversity loss. Measuring faecal glucocorticoid metabolites (FGM) in wildlife is of great value to measure the impact of human activities on local biodiversity because FGM offer a non-invasive way of measuring an animal's response to changes in its environment in the form of adrenocortical activity. Here, we measure the concentration of FGM in three native Australian mammal species belonging to different trophic levels: the Tasmanian devil () and the spotted-tailed quoll (), both carnivores, and an omnivore that is primarily an arboreal folivore, the brushtail possum (), and compare the FGM concentrations across three major land uses: agricultural, plantation and National Parks.
View Article and Find Full Text PDFIn species with sex-specific signalling traits that appear to be ornamental (i.e. are conspicuous and with no obvious natural selection benefit), the ornamented sex typically initiates courtship and is most active in courtship.
View Article and Find Full Text PDFSperm competition results from postcopulatory continuation of male-male competition for paternity. The level of sperm competition is predicted to be highest in species with greater polyandry and weakest in monogamous pairs. Sperm competition levels can be indexed using traits that reflect male investment in fertilization, particularly relative testes mass (RTM).
View Article and Find Full Text PDFSocial learning can reduce the costs associated with trial-and-error learning. There is speculation that social learning could contribute to trap and bait avoidance in invasive species like the common brushtail possum ()-a marsupial for which social learning has not previously been investigated. In large outdoor pens, we presented wild-caught 'demonstrator' possums with puzzle devices containing an attractive food reward; 2 of 8 demonstrators accessed the reward the first night the puzzle was presented and another three succeeded on later nights.
View Article and Find Full Text PDFAnticoagulant rodenticides (ARs) used to control mammalian pest populations cause secondary exposure of predatory species throughout much of the world. It is important to understand the drivers of non-target AR exposure patterns as context for assessing long-term effects and developing effective mitigation for these toxicants. In Australia, however, little is known about exposure and effects of ARs on predators.
View Article and Find Full Text PDFLead poisoning, mainly through incidental ingestion of lead ammunition in carcasses, is a threat to scavenging and predatory bird species worldwide. In Australia, shooting for animal control is widespread, and a range of native scavenging species are susceptible to lead exposure. However, the prevalence of lead exposure in Australia's scavenging and predatory birds is largely unknown.
View Article and Find Full Text PDFHorse trainers and riders may have preconceived ideas of horse temperament based solely on the sex of the horse. A study (n = 1233) of horse enthusiasts (75% of whom had more than 8 years of riding experience) revealed that riders prefer geldings over mares and stallions. While these data may reflect different sex preferences in horses used for sport, they may also reduce the chances of some horses reaching their performance potential.
View Article and Find Full Text PDFSex ratio biases are often inconsistent, both among and within species and populations. While some of these inconsistencies may be due to experimental design, much of the variation remains inexplicable. Recent research suggests that an exclusive focus on mothers may account for some of the inconsistency, with an increasing number of studies showing variation in sperm sex ratios and seminal fluids.
View Article and Find Full Text PDFFear of predation is a universal motivator. Because predators hunt using stealth and surprise, there is a widespread ability among prey to assess risk from chemical information - scents - in their environment. Consequently, scents often act as particularly strong modulators of memory and emotions.
View Article and Find Full Text PDFSex allocation theory predicts biased offspring sex ratios in relation to local conditions if they would maximize parental lifetime reproductive return. In mammals, the extent of the birth sex bias is often unpredictable and inconsistent, leading some to question its evolutionary significance. For facultative adjustment of sex ratios to occur, males and females would need to be detectably different from an early developmental stage, but classic sexual dimorphism arises from hormonal influences after gonadal development.
View Article and Find Full Text PDFIncreasing human population growth has led to elevated levels of human-carnivore conflict. However, some carnivore populations have adapted to urban environments and the resources they supply. Such associations may influence carnivore ecology, behaviour and life-history.
View Article and Find Full Text PDFThe eastern quoll (Dasyurus viverrinus) is a medium-sized Australian marsupial carnivore that has recently undergone a rapid and severe population decline over the 10 years to 2009, with no sign of recovery. This decline has been linked to a period of unfavourable weather, but subsequent improved weather conditions have not been matched by quoll recovery. A recent study suggested another mechanism: that declines in Tasmanian devil (Sarcophilus harrisii) populations, due to the spread of the fatal Devil Facial Tumour Disease, have released feral cats (Felis catus) from competitive suppression, with eastern quoll declines linked to a subsequent increase in cat sightings.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
November 2014
Sex allocation research in mammals has focussed almost exclusively on mothers under the assumption that the male contribution is genetically determined during meiosis and therefore not under adaptive control. Although early studies on sperm traits suggested that sex ratios were at parity, technological advances have made analysis more reliable and cheaper. Subsequently, more studies have shown variation in the production of X-/Y-chromosome-bearing spermatozoa.
View Article and Find Full Text PDFRelationships between males defending the same harem are described as cooperative or competitive and explained by mutualism, reciprocal altruism, and reproductive concessions or limited control between unequal contestants. These alternate hypotheses can be tested by removing males from harems. Some feral horse (Equus caballus) harems are defended by more than one and up to five stallions.
View Article and Find Full Text PDFPublication quantity is frequently used as a ranking metric for employment, promotion, and grant success, and is considered an unbiased metric for comparing applicants. However, research suggests that women publish fewer papers, such that the measure may not be equitable. We suggest reasons for the disparity, and potential future remedies.
View Article and Find Full Text PDFPhysiol Biochem Zool
June 2012
Biologically inert material in feces may confound interpretations of noninvasive fecal endocrine data, because it may induce variance related to differences in foraging behavior rather than to differences in endocrine activity. We evaluated two different enzyme immunoassays (EIAs) for the noninvasive evaluation of adrenocortical activity in ground-feeding aardwolves (Proteles cristata) and tested the influence of soil content in aardwolf feces on the interpretation of fecal glucocorticoid metabolite data. Using adrenocorticotropic hormone (ACTH) challenges for validation, we successfully identified a cortisol EIA suitable for assessing adrenocortical activity in aardwolves.
View Article and Find Full Text PDFRegulative endocrine mechanisms influence the reproductive behaviour and success of mammals, but they have been studied predominantly in domestic and captive animals. The study aims at describing the pattern of faecal 20-oxopregnane and oestrogen concentrations during pregnancy in wild plains zebra Equus quagga chapmani. Data were collected during wet and dry seasons 2007-2009.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
August 2009
In many mammals, females form close social bonds with members of their group, usually between kin. Studies of social bonds and their fitness benefits have not been investigated outside primates, and are confounded by the relatedness between individuals in primate groups. Bonds may arise from kin selection and inclusive fitness rather than through direct benefits of association.
View Article and Find Full Text PDFThe efficacy of contraceptive treatments has been extensively tested, and several formulations are effective at reducing fertility in a range of species. However, these formulations should minimally impact the behavior of individuals and populations before a contraceptive is used for population manipulation, but these effects have received less attention. Potential side effects have been identified theoretically and we reviewed published studies that have investigated side effects on behavior and physiology of individuals or population-level effects, which provided mixed results.
View Article and Find Full Text PDFBackground: Natural selection should favour the ability of mothers to adjust the sex ratio of offspring in relation to the offspring's potential reproductive success. In polygynous species, mothers in good condition would be advantaged by giving birth to more sons. While studies on mammals in general provide support for the hypothesis, studies on humans provide particularly inconsistent results, possibly because the assumptions of the model do not apply.
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