Experimental evaluation of koala scat persistence and detectability with implications for pellet-based fauna census

Establishing species distribution and population trends are basic requirements in conservation biology, yet acquiring this fundamental information is often difficult. Indirect survey methods that rely on fecal pellets (scats) can overcome some difficulties but present their own challenges. In particular, variation in scat detectability and decay rate can introduce biases. We studied how vegetation communities affect the detectability and decay rate of scats as exemplified by koalas Phascolarctos cinereus: scat detectability was highly and consistently dependent on ground layer complexity (introducing up to 16% non-detection bias); scat decay rates were highly heterogeneous within vegetation communities; exposure of scats to surface water and rain strongly accelerated scat decay rate and finally, invertebrates were found to accelerate scat decay rate markedly, but unpredictably. This last phenomenon may explain the high variability of scat decay rate within a single vegetation community. Methods to decrease biases should be evaluated when planning scat surveys, as the most appropriate method(s) will vary depending on species, scale of survey and landscape characteristics. Detectability and decay biases are both stronger in certain vegetation communities, thus their combined effect is likely to introduce substantial errors in scat surveys and this could result in inappropriate and counterproductive management decisions

Susceptibility to a sexually transmitted disease in a wild koala population shows heritable genetic variance but no inbreeding depression

The koala, one of the most iconic Australian wildlife species, is facing several concomitant threats that are driving population declines. Some threats are well known and have clear methods of prevention (e.g., habitat loss can be reduced with stronger land-clearing control), whereas others are less easily addressed. One of the major current threats to koalas is chlamydial disease, which can have major impacts on individual survival and reproduction rates and can translate into population declines. Effective management strategies for the disease in the wild are currently lacking, and to date we know little about the determinants of individual susceptibility to disease. Here we investigated the genetic basis of variation in susceptibility to chlamydia using one of the most intensively studied wild koala populations. We combined data from veterinary examinations, chlamydia testing, genetic sampling and movement monitoring. Out of our sample of 342 wild koalas, 60 were found to have chlamydia. Using genotype information on 5007 SNPs to investigate the role of genetic variation in determining disease status, we found no evidence of inbreeding depression, but a heritability of 0.11 (95%CI = 0.05 – 0.23) for the probability that koalas had chlamydia. Heritability of susceptibility to chlamydia could be relevant for future disease management, as it suggests adaptive potential for the population

Thar She Blows! A Novel Method for DNA Collection from Cetacean Blow

Background: Molecular tools are now widely used to address crucial management and conservation questions. To date, dart biopsying has been the most commonly used method for collecting genetic data from cetaceans; however, this method has some drawbacks. Dart biopsying is considered inappropriate for young animals and has recently come under scrutiny from ethical boards, conservationists, and the general public. Thus, identifying alternative genetic collection techniques for cetaceans remains a priority, especially for internationally protected species. Methodology/Principal Findings: In this study, we investigated whether blow-sampling, which involves collecting exhalations from the blowholes of cetaceans, could be developed as a new less invasive method for DNA collection. Our current methodology was developed using six bottlenose dolphins, Tursiops truncatus, housed at the National Aquarium, Baltimore (USA), from which we were able to collect both blow and blood samples. For all six individuals, we found that their mitochondrial and microsatellite DNA profile taken from blow, matched their corresponding mitochondrial and microsatellite DNA profile collected from blood. This indicates that blow-sampling is a viable alternative method for DNA collection. Conclusion/Significance: In this study, we show that blow-sampling provides a viable and less invasive method for collection of genetic data, even for small cetaceans. In contrast to dart biopsying, the advantage of this method is that it capitalizes on the natural breathing behaviour of dolphins and can be applied to even very young dolphins. Both biopsy and blow-sampling require close proximity of the boat, but blow-sampling can be achieved when dolphins voluntarily bowride and involves no harmful contact

Predictable males and unpredictable females: repeatability of sociability in eastern water dragons

There is growing evidence for consistent among-individual variation in individual sociability (e.g., tendency to be sociable) in a number of species. However, sexes often differ in their social behaviors, as well as the selection pressures which they experience. This may translate into differences in repeatability of sociability, although this has not yet been tested. Here, we investigated whether eastern water dragons (Intellegama leseurii) exhibited evidence of consistent among-individual variation (i.e., repeatability) in 4 different measurements of sociability. Specifically, we measured sociability in 4 ways (degree, centrality, proportion of time spent being social, and number of preferences), and tested whether there was evidence for sex differences in the repeatability of these sociability measurements, or whether observed levels of repeatability could be explained by a stable social environment. Our findings provide new evidence for sex differences in social personality: we found that males were significantly repeatable in 3 of 4 sociability measurements (degree, centrality, and proportion of time spent being social), whereas females were not. Further, we found that these differences were not a result of differences in the dynamics of the social environment. We discuss our findings in the context of sexual selection, as well as sex differences in the evolutionary drivers of social behavior

Individual variation in the social plasticity of water dragons

Individuals should alter when they socially associate with conspecifics to avoid potentially costly interactions. Moreover, individuals may vary in their propensity to use information about conspecifics when making such social decisions. However, surprisingly little is known about either the determinants of or the individual variation in such “social plasticity.” We show here that eastern water dragons (Intellegama lesueurii lesueurii) may simultaneously use information from different components of their social environment when deciding whether to socially associate. In particular, we found that individuals altered when they socially associated with conspecifics according to the levels of potential conflict and competition in their social environment; both sexes socially associated more at higher local density than would be expected under increased random encounters. Further, females were more likely to socially associate during the breeding season and when there were more males and/or conspecifics whom they typically avoided in their social environment. This suggests that females may seek safety in numbers when the potential for intrasexual conflict or sexual harassment is high. Using a behavioral reaction norm framework, we also provide novel evidence to show that individuals vary in the extent and direction of their social plasticity and that males varied more than females. Our study thus implies that individuals use multiple cues in their environment when deciding to socially associate and that the resulting social plasticity varies between the sexes and between individuals

Lifetime stability of social traits in bottlenose dolphins

Taylor Evans et al. present analyses based on 32 years of observations of dolphin social behaviour in Shark Bay, Western Australia. Their findings indicate that individual social traits, such as preference for time spent alone vs in groups, remain stable throughout an individual’s lifetime, despite physiological and social changes through adulthood

Eastern water dragons use alternative social tactics at different local densities

Abstract: Animals’ affiliative behaviour is, in many species, driven by population density. Although the causes of such an effect are probably varied, affiliative social behaviour can sometimes be used to minimise conflict and competition when conspecific density is high. However, individuals might instead use multiple different social tactics (e.g. social avoidance or social preference) in order to optimally minimise competition and social conflict at different local densities. Here, we investigated whether eastern water dragons (Intellegama lesueurii) use alternative social tactics at different local densities. Interestingly, we found that whilst the number of casual associations per individual increased linearly with density, as predicted by our null expectation, the relationship with density differed between social avoidance and social preference. In particular, individuals had more preferential associations at intermediate density but more avoidances at high density. This suggests that both male and female dragons use alternative social tactics according to the density of their social environment, possibly to optimally reduce social conflict. Significance statement: This study investigated the relationship between local density and social tactics (e.g. social preference and social avoidance) in eastern water dragons. We demonstrate that dragons use different social tactics according to local density. We therefore present evidence that dragons may use alternative social tactics to optimally reduce competition and conflict in their local environment

Rôles et limites de la psychologie dans la formation des enseignants d'après les <i>Conférences sur l'éducation</i> de W. James

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