Background The koala (Phascolarctos cinereus), an iconic yet endangered specialised folivore experiencing widespread decline across Australia, is the focus of many conservation programs. Whilst animal translocation and progressive conservation strategies such as faecal inoculations may be required to bring this species back from the brink of extinction, insight into the variation of host-associated gut microbiota and the factors that shape this variation are fundamental for their success. Despite this, very little is known about the landscape variability and factors affecting koala gut microbial community dynamics. We used large scale field surveys to evaluate the variation and diversity of koala gut microbiotas and compared these diversity patterns to those detected using a population genetics approach. Scat samples were collected from five locations across South East Queensland with microbiota analysed using 16S rRNA gene amplicon sequencing. Results Across the landscape koala gut microbial profiles showed large variability, with location having a large effect on bacterial community composition and bacterial diversity. Certain bacteria were found to be significantly differentially abundant amongst locations; koalas from Noosa showed a depletion in two bacterial orders (Gastranaerophilales and Bacteroidales) which have been shown to provide beneficial properties to their host. Koala gut microbial patterns were also not found to mirror population genetic patterns, a molecular tool often used to design conservation initiatives. Conclusions Our data shows that koala gut microbiotas are extremely variable across the landscape, displaying complex micro- and macro- spatial variation. By detecting locations which lack certain bacteria we identified koala populations that may be under threat from future microbial imbalance or dysbiosis. Additionally, the mismatching of gut microbiota and host population genetic patterns exposed important population structure that has previously gone undetected across South East Queensland. Overall, this baseline data highlights the importance of integrating microbiota research into conservation biology in order to guide successful conservation programs such as species translocation and the implementation of faecal inoculations.

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Chemical communication by scent‐marking is widespread among mammals and can serve different purposes, such as territory demarcation, mate attraction and self‐advertisement. In this study, we examined scent‐marking behavior by subordinate Eurasian beavers (Castor fiber) in a population in southeast Norway. We conducted scent experiments in 18 family groups, simulating a territory intruder using experimental scent mounds (ESM). In total, we recorded 196 territorial reactions (destroying and/or overmarking of scent mounds). Subordinates contributed 14% of all territorial reactions and first overmarked 12% of the ESM, and the number of subordinates in the family group did not increase the total number of territorial reactions. This suggests that the contribution by subordinates plays a minor role in territorial defense. The number of territorial reactions by subordinates was positively related to the age of their parents, suggesting that subordinates might take over territorial duties with increasing parental senescence, likely because they have increased chances of inheriting the territory. Increased experience in territorial activities possibly helps subordinates to successfully gain and defend a territory of their own.

Fragmentation of habitat is a major threat across a wide range of taxa. Subsequent effects include reduced population sizes and isolation of populations. Both can have detrimental consequences for populations as they increase the risk of genetic erosion. While it is critical to prevent and, if required, reverse genetic erosion, we often lack adequate data to assess whether and how much genetic erosion has occurred. Here, we present a genetic monitoring study where we investigated changes in genetic diversity and genetic patterns in a threatened, specialist mammal, the koala (Phascolarctos cinereus). Our study population inhabits an increasingly fragmented landscape and has experienced a sharp decline in population size within the past three decades. We used 1038 single nucleotide polymorphic loci (SNPs) to compare measures of genetic diversity between samples collected in 2018 and in 2006 (two generations prior) and investigated simultaneous changes in the environment. We found a decline in both heterozygosity and effective population size (N e ), and an increase in sub-structuring, average relatedness, and inbreeding (F IS ) alongside an increasingly threatening and more fragmented environment. Given the extent of genetic erosion in only two generations, we urge consideration for the implementation of mitigation measures for this population and for threatened populations in similar conditions. Our study further emphasizes the importance of effective management of at-risk populations including monitoring of genetic erosion.

Protected areas (PAs) are crucial conservation tools implemented worldwide to conserve biodiversity. Although PAs can positively impact wildlife populations, their ecological outcomes vary substantially depending on PA management and governance. Recent calls have highlighted the need to better assess the role of area-based conservation in preventing biodiversity loss. This is crucial to improve PA effectiveness in order to meet global biodiversity goals. Here we take advantage of a unique dataset composed of 2230 surveys conducted with koala detection dogs across Eastern Australia, to assess how protection status affected the occurrence of a threatened specialist folivore. We assessed if coverage of protected forest influenced koala presence or absence at two spatial scales (1 and 3 km), for (i) strictly and (ii) all protected areas. We also investigated if PA effects were explained by differences in habitat composition (percentage of secondary forest) between protected and unprotected areas. Taking confounding factors into account, we showed that forest protection (all IUCN categories) had a significant positive effect on koala occurrence, which increased by ~ 10% along the forest protection gradient. Contrarily, koala occurrence was not affected by strictly protected areas. In addition, adding the percentage of secondary forests in our models did not modify the statistical effect of PAs on koala occurrence, suggesting that forest composition is not the driver of the observed difference along the protection gradient. Our results contribute to a broader understanding of the effects of PAs on a threatened marsupial and call for further attention to assessments of PA effectiveness in Eastern Australia, a global biodiversity hotspot.