Genetic and demographic vulnerability of adder populations: Results of a genetic study in mainland Britain

Genetic factors are often overlooked in conservation planning, despite their importance in small isolated populations. We used mitochondrial and microsatellite markers to investigate population genetics of the adder (Vipera berus) in southern Britain, where numbers are declining. We found no evidence for loss of heterozygosity in any of the populations studied. Genetic diversity was comparable across sites, in line with published levels for mainland Europe. However, further analysis revealed a striking level of relatedness. Genetic networks constructed from inferred first degree relationships suggested a high proportion of individuals to be related at a level equivalent to that of half-siblings, with rare inferred full-sib dyads. These patterns of relatedness can be attributed to the high philopatry and low vagility of adders, which creates high local relatedness, in combination with the polyandrous breeding system in the adder, which may offset the risk of inbreeding in closed populations. We suggest that reliance on standard genetic indicators of inbreeding and diversity may underestimate demographic and genetic factors that make adder populations vulnerable to extirpation. We stress the importance of an integrated genetic and demographic approach in the conservation of adders, and other taxa of similar ecology.

Elliott traps found to be ineffective for the survey of swamp skink (Lissolepis coventryi): a cautionary tale of outdated survey guidelines

Context Cryptic (i.e. secretive, elusive or well camouflaged) species are often very challenging to accurately survey. Because many cryptic species are threatened, the development of robust and efficient survey methods to detect them is critically important for conservation management. The swamp skink (Lissolepis coventryi) is an example of an elusive and threatened species; it inhabits densely vegetated, wet environments throughout south-east Australia. The swamp skink occurs in peri-urban areas and faces many human-induced threats including habitat loss, introduced predators and environmental pollution. Effective and reliable survey methods are therefore essential for its conservation. Aims This study aimed to review the current swamp skink survey guidelines to compare the detection success of Elliott traps with two alternative methods: passive infrared cameras (camera traps) and artificial refuges. Methods Detection probabilities for the swamp skink were compared using Elliott traps, artificial refuges and camera traps at two known populations on the Mornington Peninsula, Victoria, Australia. Key results Artificial refuges and camera traps were significantly more successful than Elliott traps at detecting swamp skinks. Conclusions Elliott traps are currently regarded as the standard technique for surveying swamp skinks; however, these traps were the least successful of the three methods trialled. Therefore, the use of Elliott traps in future swamp skink presence–absence surveys is not recommended. Implications Many previous surveys utilising Elliott traps have failed to detect swamp skinks in habitats where they are likely to occur. Our findings suggest that at least some of these past surveys may have reported false absences of swamp skinks, potentially resulting in poor planning decisions. A reduction in the reliance on Elliott trapping is likely to increase future swamp skink detection success, broaden our understanding of this cryptic species and aid conservation efforts. Our results emphasise that it is essential to regularly review recommended survey methods to ensure they are accurate and effective for target species.

Priorities for management of chytridiomycosis in Australia: saving frogs from extinction

To protect Australian amphibian biodiversity, we have identified and prioritised frog species at an imminent risk of extinction from chytridiomycosis, and devised national management and research priorities for disease mitigation. Six Australian frogs have not been observed in the wild since the initial emergence of chytridiomycosis and may be extinct. Seven extant frog species were assessed as needing urgent conservation interventions because of (1) their small populations and/or ongoing declines throughout their ranges (southern corroboree frog (Pseudophryne corroboree, New South Wales), northern corroboree frog (Pseudophryne pengilleyi, Australian Capital Territory, New South Wales), Baw Baw frog (Philoria frosti, Victoria), Litoria spenceri (spotted tree frog, Victoria, New South Wales), Kroombit tinkerfrog (Taudactylus pleione, Queensland), armoured mist frog (Litoria lorica, Queensland)) or (2) predicted severe decline associated with the spread of chytridiomycosis in the case of Tasmanian tree frog (Litoria burrowsae, Tasmania). For these species, the risk of extinction is high, but can be mitigated. They require increased survey effort to define their distributional limits and to monitor and detect further population changes, as well as well-resourced management strategies that include captive assurance populations. A further 22 frog species were considered at a moderate to lower risk of extinction from chytridiomycosis. Management actions that identify and create or maintain habitat refugia from chytridiomycosis and target other threatening processes such as habitat loss and degradation may be effective in promoting their recovery. Our assessments for some of these species remain uncertain and further taxonomical clarification is needed to determine their conservation importance. Management actions are currently being developed and trialled to mitigate the threat posed by chytridiomycosis. However, proven solutions to facilitate population recovery in the wild are lacking; hence, we prioritise research topics to achieve this aim. Importantly, the effectiveness of novel management solutions will likely differ among species due to variation in disease ecology, highlighting the need for species-specific research. We call for an independent management and research fund of AU$15 million over 5 years to be allocated to recovery actions as determined by a National Chytridiomycosis Working Group of amphibian managers and scientists. Procrastination on this issue will likely result in additional extinction of Australia’s amphibians in the near future.