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Climatic variation can impact populations of ectotherms by altering reproduction, development, and survival. While a warm climate can provide additional thermal opportunities for ectotherms, excessively warm conditions can restrict activity in avoidance of lethal temperatures. However, ectotherms are not necessarily passive to thermal conditions, and often employ flexible thermoregulatory behaviour to accommodate environmental variation. Here, we examine whether the Australian jacky dragon lizard, Amphibolurus muricatus, can compensate for reduced basking opportunity by basking with greater intensity, and how the thermal environment influences reproductive success in females. Overall, there was no compelling evidence for compensatory thermoregulatory behaviour in response to reduced basking opportunity. Moreover, females with reduced thermal opportunities did not produce eggs, although reproductive success was quite low for both groups, so additional factors may have limited reproduction in the colony. This study allows insight into the links between climate and population persistence in wild animals by providing crucial and rare data on how thermal environment impacts reproduction in an egg-laying lizard.
The Australian fig psylloid, Mycopsylla fici, is a sap-feeding insect herbivore that is host-specific to the Moreton Bay fig, Ficus macrophylla. It has periodic major outbreaks that can cause complete defoliation of individual trees and massive decrease in local leaf and fruit availability, with significant effects for many insect and vertebrate species that utilise the tree’s resources. We used ⅛ of an Illumina MiSeq run to sequence genomic DNA from two pools of five psylloids from two different field sites. We identified 14 polymorphic microsatellite loci and characterised them in 43 individuals from two populations (Sydney and Lord Howe Island, Australia). Within populations, the number of alleles ranged from 4 to 15 per locus with observed heterozygosity of 0–0.9. Four loci deviated from Hardy–Weinberg equilibrium. The microsatellite primers will be useful for the study of population genetics and gene flow within and between psylloid populations.
Conservation plans can benefit from understanding patterns of genetic structure because many endangered species are spatially fragmented. In particular, headwater species in high elevations are expected to exhibit a high level of population structure, as dispersal through lowland streams may be limited. Euastacus urospinosus is an endangered freshwater crayfish that, until recently, was thought to have a distribution of just 200 km2. In the current study, we identified a total of 26 locations for this species across a 1225 km2 region spanning the Brisbane and Mary River catchments of south-east Queensland, Australia. We then used mitochondrial DNA sequence data to investigate the population structure and the phylogeographic divergence between four uplands. We found significant population differentiation for this species, which conforms to the headwater model of genetic structure. Further, we found that fragmentation between these uplands is most likely historical, as the first divergence between lineages dated back 2.1 million years. Overall, we found no reason to remove the conservation rating of ‘endangered’ for this species. Conservation plans should seek to preserve the genetic integrity of these uplands by considering them to be genetically distinct and isolated populations.
The western saw-shelled turtle is listed as threatened globally, nationally, and within the Australian state of New South Wales. Although nearly all of the geographic range of the species lies within New South Wales, little information has been available on the distribution, abundance and structure of New South Wales populations. Through a survey of 60 sites in 2012–15, I established that M. bellii is much more widely distributed in New South Wales than has previously been recognised, comprising four disjunct populations, including two in the New South Wales portion of the Border Rivers basin. It occurs mainly in larger, cooler rivers upstream of barriers to dispersal of the Macquarie turtle, Emydura macquarii macquarii. Although M. bellii is locally abundant, its populations are greatly dominated by large adults and recruitment appears to be low. Eye abnormalities are common in some populations but do not necessarily impair body condition or preclude long-term survival. The species is threatened by competition with E. macquarii, which appears to be expanding its range through translocation by humans, and possibly by predation, disease and drought. Long-term monitoring of M. bellii is needed to assess population trends and responses to threats, and active management to restrict the further spread of E. macquarii is probably required to ensure the persistence of M. bellii throughout its current range.
Animal research guidelines recognise that trapped animals can potentially be subjected to heat stress, but recommendations are limited to avoiding exposing traps to weather extremes. Intuitively, shading metal box traps should be beneficial in warm to hot climates. Temperatures inside metal box traps were measured within traps located in direct sunlight concurrently with ones covered with artificial shading. Additionally, comparisons were conducted in continuous shade cast by ground-cover vegetation, and in stippled sunlight under an artificial lattice. Deep continuous shade from vegetation was most effective and able to keep traps within 5°C of ambient. Artificial shading using dark shade cloth could actually elevate trap temperatures above that in uncovered traps when exposed to direct sunshine. Reflective foil insulation cover not only provided rain protection for traps but was the most effective shading method trialled for reducing both the rate at which traps heated after sunrise and the maximum temperature reached during the day when exposed to direct sunshine. The use of foil sleeves can provide an extra level of protection from excessive heat exposure to trapped animals, keeping trap temperatures as much as 15°C lower than unprotected traps.
Matt W. Hayward, Aline Si Lin Poh, Jennifer Cathcart, Chris Churcher, Jos Bentley, Kerryn Herman, Leah Kemp, Noel Riessen, Phil Scully, Cheong Hoong Diong, Sarah Legge, Andrew Carter, Heloise Gibb, J. Anthony Friend
Despite a vigorous reintroduction program between 1985 and 2010, numbat populations in Western Australia are either static or declining. This study aimed to document the population ecology of numbats at two sites that are going against this trend: Scotia Sanctuary in far western New South Wales and Yookamurra Sanctuary in the riverland of South Australia. Scotia (64 659 ha) and Yookamurra (5026 ha) are conservation reserves owned and managed by the Australian Wildlife Conservancy and where numbats were reintroduced in 1999 and 1993 respectively. Both sites have large conservation-fence-protected introduced-species-free areas where there are no cats (Felis catus) or red foxes (Vulpes vulpes). Numbats were sourced from both wild and captive populations. From small founder populations, the Scotia numbats are now estimated to number 169 (113–225) with 44 at Yookamurra. Radio-collared individuals at Scotia were active between 13 and 31°C. Females had home ranges of 28.3 ± 6.8 ha and males 96.6 ± 18.2 ha, which leads to an estimated sustainable population or carrying capacity of 413–502 at Scotia. Captive-bred animals from Perth Zoo had a high mortality rate upon reintroduction at Scotia due to predation by raptors and starvation. The habitat preferences for mallee with a shrub understorey appear to be driven by availability of termites, and other reintroduced ecosystem engineers appear to have been facilitators by creating new refuge burrows for numbats. This study shows that numbats can be successfully reintroduced into areas of their former range if protected from introduced predators, and illustrates the difficulties in monitoring such cryptic species.
Documenting natural behaviours may be an important component of conservation management of threatened species in that deviations from some behaviours may serve as early warning signs of subsequent deteriorating condition and the possible need for intervention. We described predation behaviour of the endangered Australian scincid lizard Tiliqua adelaidensis from 23 burrows by watching video images from cameras over 10 days each month for five months in spring and summer. We observed 341 predation attempts, of which 277 were successful. These lizards predominantly ambush passing prey from their burrow entrance without completely emerging from the burrow. Orthopterans were the major component of their captures; prey captures peaked in November and December. We measured the proportion of unsuccessful foraging attempts, the proportion of foraging attempts that involved full emergence, the mean distance a lizard moved away from the burrow entrance, and the proportion of plant parts in the diet. We suggest that if any of these parameters increase it could indicate the requirement for intervention management. Our study supports the view that behavioural monitoring could be considered as an integral component of any conservation management of endangered animal species.
Bight redfish, Centroberyx gerrardi, is a demersal teleost endemic to continental shelf and upper slope waters of southern Australia. Throughout most of its range, C. gerrardi is targeted by a number of separately managed commercial and recreational fisheries across several jurisdictions. However, it is currently unknown whether stock assessments and management for this shared resource are being conducted at appropriate spatial scales, thereby requiring knowledge of population structure and connectivity. To investigate population structure and connectivity, we developed 16 new polymorphic microsatellite markers using 454 shotgun sequencing. Two to 15 alleles per locus were detected. There was no evidence of linkage disequilibrium between pairs of loci and all loci except one were in Hardy–Weinberg equilibrium. Cross-amplification trials in the congeneric C. australis and C. lineatus revealed that 11 and 16 loci are potentially useful, respectively. However, deviations from Hardy–Weinberg equilibrium and linkage disequilibrium between pairs of loci were detected at several of the 16 markers for C. australis, and therefore the number of markers useful for population genetic analyses with C. lineatus is likely considerably lower than 11.
Populations in fragmented urban remnants may be at risk of genetic erosion as a result of reduced gene flow and elevated levels of inbreeding. This may have serious genetic implications for the long-term viability of remnant populations, in addition to the more immediate pressures caused by urbanisation. The population genetic structure of the generalist skink Ctenotus fallens was examined using nine microsatellite markers within and among natural vegetation remnants within a highly fragmented urban matrix in the Perth metropolitan area in Western Australia. These data were compared with samples from a large unfragmented site on the edge of the urban area. Overall, estimates of genetic diversity and inbreeding within all populations were similar and low. Weak genetic differentiation, and a significant association between geographic and genetic distance, suggests historically strong genetic connectivity that decreases with geographic distance. Due to recent fragmentation, and genetic inertia associated with low genetic diversity and large population sizes, it is not possible from these data to infer current genetic connectivity levels. However, the historically high levels of gene flow that our data suggest indicate that a reduction in contemporary connectivity due to fragmentation in C. fallens is likely to result in negative genetic consequences in the longer term.
Hatchling overwintering inside the natal nest is a strategy used by several Northern Hemisphere species of freshwater turtles. We recorded hatchling overwintering in the nest by Chelodina longicollis (Chelidae) in south-eastern Australia, during three reproductive seasons. Hatchlings spent, on average, 320 days inside the nest from the date eggs were laid until emergence. Some nests were carefully opened adjacent to the nest plug, one during winter and one in spring, to confirm that eggs had hatched and were not in diapause, although we could not precisely confirm hatching dates. Despite our small sample size, we observed a dichotomous overwintering strategy, with hatchlings from one nest emerging in autumn and spending their first winter in the aquatic environment, and hatchlings from three nests overwintering in the nest and emerging in spring. These findings expand the phylogenetic range of turtles exhibiting hatchling overwintering behaviour. Future research should evaluate whether this strategy is widespread among other long-necked turtles in temperate regions and examine physiological mechanisms involved in coping with winter temperatures.
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