Nick Clemann

Historical biogeography, phylogenetic relationships and intraspecific diversity of agamid lizards in the Central Asian deserts of Kazakhstan and Uzbekistan

The Central Asian agamid lizards are ecologically and morphologically diverse, occurring across a broad range of desert environments in this biogeographically important region. It is probable that past climatic shifts have significantly influenced the diversification patterns and distributions of the agamid lizards of this region. To assess this within a phylogenetic framework we sequenced a approximately 1200 bp region of mitochondrial DNA and a approximately 1200 bp nuclear gene (RAG-1), incorporating both inter- and intraspecific sampling across Central Asian agamids. Our topology and divergence time estimates support an Eocene origin of the Agaminae subfamily on the Indian subcontinent, coinciding with the collision of India into Eurasia. The onset of aridification in Central Asia during the Late Oligocene, resulting from the retreat of the Paratethys Sea and the intensified uplift of the Tibetan-Himalayan complex, probably played an important role in the diversification of Phrynocephalus, one of the three genera studied. Intensification of aridity and geologic events in the Plio-Pleistocene and Quaternary glacial cycling probably had a significant influence on intraspecific diversification patterns within Phrynocephalus.

Activity patterns and habitat preferences of translocated and resident tiger snakes (Notechis scutatus) in a suburban landscape

Translocation of snakes is a common practice for managing human–snake conflict in many parts of Australia. The impact of this management on individual snakes is not known. Differences between translocated and non-translocated snakes in terms of their activity patterns and habitat use are likely to indicate an impact on individual snakes from this procedure. We investigated these issues in a suburban parkland close to Melbourne for one of the most familiar of these snakes, the tiger snake (Notechis scutatus). This parkland is frequently used by licenced snake controllers to release snakes that have been removed from nearby private properties at the owner’s request. We used two techniques to assess activity patterns and habitat preferences of resident and translocated snakes: direct observations of tiger snakes that were resident in the park, and radiotelemetry to compare a subset of resident snakes with translocated conspecifics. The size of our transmitters dictated that we only use telemetry for large snakes (≥750 mm snout–vent length), even though the resident population consisted mainly of intermediate-sized females (560–760 mm snout–vent length). Non-telemetred resident snakes were readily observed during spring, but rarely observed in summer and early autumn. Translocated snakes travelled greater distances than resident telemetred snakes, although there was no difference in the frequency of movements. For both groups the degree of cloud cover and maximum daily temperature had a significant influence on daily activity, with snakes being more likely to be active on relatively cool, sunny days. Relative humidity, wind speed and rainfall did not exert a significant influence on activity. Snakes exhibited bimodal peaks in daily activity, avoiding the hottest part of the day. Both resident and translocated snakes showed a preference for grassy woodlands associated with hills, but avoided escarpment woodlands and open plains. Floodplain riparian woodland was avoided by resident snakes, but used in proportion to its availability by translocated snakes. Because translocated snakes released at the study site moved larger distances and showed different habitat preferences to resident snakes we conclude that this practice influences individual snakes. Until the implications of translocation for both snakes and humans are fully understood, we recommend caution in the use of this management practice.

The effects of translocation on the spatial ecology of tiger snakes (Notechis scutatus) in a suburban landscape

In many suburban parts of Australia the removal of snakes from private property by licenced snake catchers is employed to mitigate perceived risks to humans and their pets. The number of snakes translocated around greater Melbourne, Victoria, each year can be very high (at least many hundreds). However, the effects of translocation on the behaviour and welfare of individual snakes, and the impact on existing snake populations at release sites are unknown. We used radio-telemetry of ‘resident’ and translocated snakes to investigate the consequences of translocation on the spatial ecology of tiger snakes (Notechis scutatus) in a suburban parkland near Melbourne. Fourteen snakes (two female and four male residents, and four female and four male translocated snakes) implanted with radio-transmitters were tracked between spring 2002 and autumn 2003. Translocated snakes exhibited home ranges ~6 times larger than those of residents, although each group maintained core ranges of similar size. Translocated snakes travelled longer distances and were often located in residential areas adjacent to the park, whereas resident snakes were never located outside of the park.

Wetland characteristics influence disease risk for a threatened amphibian

Identifying determinants of the probability and intensity of infections is important for understanding the epidemiology of wildlife diseases, and for managing their impact on threatened species. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis, has decimated populations of some amphibians. However, recent studies have identified important environmental constraints on the disease, related to the pathogens physiological tolerances. In this study, we identified several intrinsic and extrinsic determinants of the probability and intensity of chytrid infections for the threatened growling grass frog (Litoria raniformis) in southeastern Australia, and used mark-recapture to estimate the effect of chytrid infections on the probability of survival of these frogs. Water temperature and salinity had negative effects on both the probability and intensity of chytrid infections. We coupled models of the infection process with a model of the effect of chytrid infections on the probability of survival to assess variation in the impact of chytridiomycosis between wetlands with differing temperature and salinity profiles. Our results suggest that warm, saline wetlands may be refuges from chytridiomycosis for L. raniformis, and should be priorities for protection. Our results also suggest that management actions that increase water temperature (e.g., reducing canopy shading) and salinity (e.g., complementing inflows with groundwater) could be trialed to reduce the impacts of chytridiomycosis on this species. This and other recent studies highlight the value of research on environmental risk factors for chytridiomycosis.

Refugia and connectivity sustain amphibian metapopulations afflicted by disease

Metapopulation persistence in fragmented landscapes depends on habitat patches that can support resilient local populations and sufficient connectivity between patches. Yet epidemiological theory for metapopulations has largely overlooked the capacity of particular patches to act as refuges from disease, and has suggested that connectivity can undermine persistence. Here, we show that relatively warm and saline wetlands are environmental refuges from chytridiomycosis for an endangered Australian frog, and act jointly with connectivity to sustain frog metapopulations. We coupled models of microclimate and infection probability to map chytrid prevalence, and demonstrate a strong negative relationship between chytrid prevalence and the persistence of frog populations. Simulations confirm that frog metapopulations are likely to go extinct when they lack environmental refuges from disease and lose connectivity between patches. This study demonstrates that environmental heterogeneity can mediate host-pathogen interactions in fragmented landscapes, and provides evidence that connectivity principally supports host metapopulations afflicted by facultative pathogens.

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

Abstract. 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

Sexual Dimorphism, Diet, and Reproduction in the Swamp Skink, Egernia coventryi

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.

Snake Management on Private Properties in Melbourne, Australia

Abstract The Swamp Skink, Egernia coventryi, is an uncommon species that inhabits wetlands and swampy heaths in predominantly coastal regions of southeastern Australia. We examined museum specimens to quantify the diet, reproduction, and sexual dimorphism of E. coventryi. The mean SVL of both adult males and females was 85–86 mm, and individuals attain sexual maturity at about 72–74 mm SVL. Although the sexes did not differ in body size (SVL), males have longer and broader heads than females, both in terms of absolute head size and head size relative to body size. Females ovulate in September and October with parturition occurring in late January or early February. However, not all adult females collected during the breeding season were pregnant, suggesting that female E. coventryi may not always breed annually. Litter size in E. coventryi ranged from 1–4, with a mean litter size of 2.6. Egernia coventryi is omnivorous and a largely opportunistic forager, with spiders (found in 16 of 47 individuals, 34%), beetles (26%), lepidopterans (17%), ants (11%), hemipterans (9%) and aquatic amphipods (9%) the most common animal prey items found in the alimentary canals of individuals. However, plant materials (e.g., fruits/berries, seeds, other vegetation) also were found in the stomachs of the majority of the specimens (66%). Sloughed skin (26%) and the tail fragment of another E. coventryi were found in the alimentary tracts of preserved specimens. The majority of specimens (76%) were infested with endoparasites, with one specimen containing 130 nematodes, although the mean number of nematodes per specimen was 8.87.

Characteristics of refugia used by the threatened Australian growling grass frog (Litoria raniformis) during a prolonged drought

The occurrence of snakes on private properties concerns many residents. Translocation of snakes by licensed wildlife controllers from private properties to public land is a common management practice in Victoria, Australia. Licensed snake controllers and first contact organizations (mainly local governments) that receive calls from those wishing to have a snake removed were surveyed via phone interview or mail questionnaire to obtain insights into the management of snakes around Melbourne and in regional Victoria. Frequently, these organizations receive snake-related calls from the public, and then connect these people to snake controllers who attempt to capture and relocate the snakes. A large number of snakes are translocated each year. Controllers chose release sites based on permit stipulations, and a suite of subjectively applied criteria such as perceived suitability of habitat and distance (both near and far) from capture site/location of residents. Most controllers used multiple release sites, although some released all snakes at a single site. The authors suggest that the scale and scope of this practice has implications for snake populations at both “donor” and release sites, and, potentially, for humans near to release sites.

Phylogenetic evidence of historic mitochondrial introgression and cryptic diversity in the genus Pseudemoia (Squamata: Scincidae).

Abstract Context. Because they are dependent on water, drought can have a deleterious impact on aquatic-breeding amphibians. One such species, the threatened growling grass frog (Litoria raniformis) occurs in south-eastern Australia, a region that has recently emerged from a decade-long, severe drought. Aims. We aimed to identify features of drought refugia that facilitate persistence of L. raniformis, so as to provide guidance to natural-resource managers attempting to conserve populations of this species during drought. Methods. We conducted repeat surveys for L. raniformis at 90 water bodies at the end of the ‘millennium drought’. We recorded the following six environmental variables for each water body: origin (natural or not), type (lotic or lentic), proportion of aquatic vegetation cover, conductivity of water, riparian tree-canopy cover and distance to the nearest woodland. We used occupancy models to relate the presence of L. raniformis to these variables, while accounting for uncertain detection. Key results. Water-body type (natural or artificial, lentic or lotic) had minimal influence on the probability of occupancy by L. raniformis. We found a strong negative relationship between occupancy and conductivity of water (a surrogate for salinity), and a positive relationship between occupancy and the proportion of aquatic vegetation. We found a negative relationship between detection and the extent of aquatic vegetation, and a mildly negative effect of canopy cover on occupancy. Conclusions. Habitat characteristics are more important indicators of the quality of drought refugia for L. raniformis than is the type of water body per se. Consequently, we identified aquatic vegetation and salinity as important targets for management when planning the retention, creation or restoration of habitat to facilitate persistence of L. raniformis during drought. Implications. Our results highlighted aquatic vegetation and water-quality parameters that are likely to facilitate the persistence of L. raniformis during drought. Assessing the effectiveness of our recommendations in an experimental framework would ensure that conservation management of this frog can be refined over time.