William S. Osborne

Geographic Variation in the Advertisement Call Structure of Litoria verreauxii (Anura: Hylidae)

Abstract Many evolutionary processes have been identified that could lead to signal variability among populations despite stabilizing selection to maintain conspecific recognition. By examining among-population variation in mate recognition signals we may gain insights into the processes behind the evolution of such variation. We documented among-population variation in the advertisement call of Litoria verreauxii in the Australian Snowy Mountains to determine how call structure varied (1) across a broad geographic area, (2) from allopatry to sympatry with northern Litoria ewingii (an undescribed member of the same species complex), and (3) between two subspecies, Litoria verreauxii verreauxii and Litoria verreauxii alpina. Significant variation in all measured call properties was explained by latitude and/or longitude. Most noticeably, a strong east-west trend in introductory note duration and pulse number was detected that coincided with the transition from allopatry to sympatry with northern L. ewingii. The observed variation is discussed within the context of several evolutionary mechanisms including clinal variation and both reproductive and ecological character displacement. We found considerable variation in pulse rate among nearby allopatric populations (based upon current taxonomy). Pulse rate has been implicated in species recognition and reinforcement in L. verreauxii. Some of the among-population variation in pulse rate may reflect the presence of cryptic taxa. However, these results suggest that factors other than interspecific interactions with closely related species can lead to considerable among-population divergence in pulse rate. Finally, there was little difference in call structure between the two subspecies.

Assessment of genetic diversity in the critically endangered Australian corroboree frogs, Pseudophryne corroboree and Pseudophryne pengilleyi, identifies four evolutionarily significant units for conservation

The iconic and brightly coloured Australian northern corroboree frog, Pseudophryne pengilleyi, and the southern corroboree frog, Pseudophryne corroboree are critically endangered and may be extinct in the wild within 3 years. We have assembled samples that cover the current range of both species and applied hypervariable microsatellite markers and mitochondrial DNA sequences to assess the levels and patterns of genetic variation. The four loci used in the study were highly variable, the total number of alleles observed ranged from 13 to 30 and the average number of alleles per locus was 19. Expected heterozygosity of the four microsatellite loci across all populations was high and varied between 0.830 and 0.935. Bayesian clustering analyses in structure strongly supported four genetically distinct populations, which correspond exactly to the four main allopatric geographical regions in which the frogs are currently found. Individual analyses performed on the separate regions showed that breeding sites within these four regions could not be separated into distinct populations. Twelve mtND2 haplotypes were identified from 66 individuals from throughout the four geographical regions. A statistical parsimony network of mtDNA haplotypes shows two distinct groups, which correspond to the two species of corroboree frog, but with most of the haplotype diversity distributed in P. pengilleyi. These results demonstrate an unexpectedly high level of genetic diversity in both species. Our data have important implications for how the genetic diversity is managed in the future. The four evolutionarily significant units must be protected and maintained in captive breeding programmes for as long as it is possible to do.

An experiment to test key hypotheses of the drivers of reptile distribution in subalpine ski resorts

Summary Alpine and subalpine ecosystems support many endemic species. These ecosystems are increasingly under threat from human-induced disturbances such as habitat loss and fragmentation as a consequence of ski resort development and expansion. However, limited peer-reviewed research has investigated the impacts of ski-related disturbances on wildlife, particularly on reptiles. To address this knowledge gap, we conducted reptile surveys to determine the patterns of reptile distribution and abundance in Australian ski resorts. Then, using a factorial experimental design, we investigated 1) the influence of temperature and predation in driving observed distributions and 2) how a common ski resort management practice – mowing of modified ski slopes – affected thermal regimes and rates of predation of reptiles on ski runs. We found that the removal of vegetation structural complexity through mowing resulted in significantly higher rates of predation on plasticine models, as well as significantly altered thermal regimes. Crucially, mown ski runs had higher maximum ground temperatures that frequently exceeded the recorded critical maximum body temperatures of the target species of lizards. Thus, mowing has the potential to render these areas unsuitable for thermoregulatory purposes for a large proportion of the potential activity period of reptiles. Together, modifications of the thermal environment and elevated rates of predation appear to explain the avoidance of ski runs by reptiles. To facilitate the persistence of reptiles in disturbed subalpine environments, management plans must focus on implementing strategies that reduce the impact of human activities that alter temperature regimes and predation rates on lizards. Synthesis and Applications. We suggest that the retention of structural complexity on ski runs (e.g. through the cessation of mowing during peak reptile activity periods) and/or revegetation with native plant communities will concurrently provide refuge from predators and buffer against extreme temperatures, making ski runs more hospitable to reptiles. Based on our findings, we emphasize that effective management strategies targeting subalpine biodiversity conservation require an understanding of the drivers that determine species distributions in these landscapes.

Home ranges of, and habitat use by, the grassland earless dragon (Tympanocryptis pinguicolla) in remnant native grasslands near Canberra

The grassland earless dragon (Tympanocryptis pinguicolla) is a habitat specialist restricted to the highly fragmented native temperate grasslands of the Australian Capital Territory (ACT) and nearby New South Wales (NSW). These grasslands, which are listed as an endangered ecological community, continue to be affected by a range of processes including development and overgrazing. Although changes to its habitat present a significant threat to the grassland earless dragon, little is known about its spatial and habitat requirements. We used radio-tracking to study the home-range areas and habitat requirements of 10 adult lizards in native grassland adjacent to Canberra, ACT. We found that burrows excavated by arthropods are an important resource for grassland earless dragons, with individuals having one or two home burrows around which they maintained home ranges of between 925 m2 and 4768 m2. Fidelity to these burrows increased with the onset of winter, indicating their importance as over-winter refuge sites. Within the native grasslands, grassland earless dragons were found to use a broad range of grassland structure as habitat. This result contrasts with the prevailing view that these dragons are confined to well drained, minimally disturbed areas, which include large patches of short grass dominated by Austrodanthonia. We conclude that habitat management (i.e. grazing, mowing, burning) for this species should aim to retain structural heterogeneity of native grasslands rather than impose a uniform structure.

The life history and ecology of the Pink-tailed Worm-lizard Aprasia parapulchella Kluge – a review

This review synthesises research on the Pink-tailed Worm-lizard Aprasia parapulchella - a threatened species with life-history traits and habitat and dietary preferences that make it particularly vulnerable to decline. Further information on the ecology of A. parapulchella is required in order to develop effective approaches to conservation and management, particularly given the conservation status of the species. Aprasia parapulchella is a dietary specialist living in the burrows of small ants, the eggs and larvae of which it preys upon. It is late maturing (adult size probably attained in the third or fourth year of life), has a small clutch, is thought to be longlived and has specific habitat preferences. It has a strong association with landscapes that are characterised by outcroppings of lightly-embedded surface rocks. The lizard is associated with a particular suite of ant species and ground cover tending towards open native vegetation (grasses and shrubs) at most sites, but with regional difference...

Designing for conservation outcomes: The value of remnant habitat for reptiles on ski runs in subalpine landscapes

Subalpine ecosystems are centres of endemism that are important for biodiversity. However, these areas are under threat from the creation, expansion and continued modification of ski runs, activities that have largely negative effects on wildlife. Despite this threat, research on the impacts of ski runs is limited for reptiles—particularly regarding the value of remnant vegetation retained on ski runs. Here we quantify the effects of habitat loss and fragmentation (i.e., patch size, patch isolation and edge effects) on the abundance of a common subalpine lizard and on thermal regimes (a key determinant of lizard distribution) in an Australian ski resort. The number of lizards observed differed significantly with habitat type (ski runs vs. forested areas) and patch isolation, but not patch size. In addition, the edges of patches supported more lizards than any other habitat type. These patterns of lizard distribution can be explained, in part, by the differing thermal regimes in each habitat. Ski runs had significantly higher ground surface temperatures than any other habitat type, precluding their use for a considerable proportion of the activity period of a lizard. In comparison, edges were characterised by lower temperatures than ski runs, but higher temperatures than the core of forested areas, potentially providing a favourable environment for thermoregulation. Based on our results, we conclude that although modified ski runs have a negative effect on lizards, patches of remnant vegetation retained on ski runs are of value for reptiles and their conservation could help mitigate the negative effects of habitat loss caused by ski run creation.

How many conservation units are there for the endangered grassland earless dragons

Species are the most commonly recognised unit for conservation management, yet significant variation can exist below the level of taxonomic recognition and there is a lack of consensus around how a species might be defined. This definition has particular relevance when species designations are used to apportion conservation effort and when definitions might be made through legislation. Here, we use microsatellite DNA analyses to test the proposition that the last remaining populations of the endangered grassland earless dragon (Tympanocryptis pinguicolla) harbour substantial cryptic genetic variation. Our study provides strong evidence that long historical isolation and the recent impacts of urbanization, have led to genetic differentiation in microsatellite DNA allele frequencies and high numbers of private alleles among three genetic clusters. This differentiation is partially concordant with previous mitochondrial DNA analyses, which show the two regions (Canberra and Monaro) where this species exists, to be reciprocally monophyletic, but differs through the identification of a third genetic cluster that splits a northern Canberra cluster from that of southern Canberra. Our data also identify a stark contrast in population genetic structure between clusters such that high levels of genetic structure are evident in the highly urbanised Canberra region but not in the largely rural Monaro region. We conclude that this species, like many reptiles, harbours considerable cryptic variation and currently comprises three distinct and discrete units. These units could be classified as separate species for the purpose of conservation under the relevant Australian and international Acts drawing management appropriate to that status.

Remotely sensed agricultural modification improves prediction of suitable habitat for a threatened lizard

ABSTRACT The geographical distribution of a species is limited by factors such as climate, resources, disturbances and species interactions. Environmental niche models attempt to encapsulate these limits and represent them spatially but do not always incorporate disturbance factors. We constructed MaxEnt models derived from a remotely sensed vegetation classification with, and without, an agricultural modification variable. Including agricultural modification improved model performance and led to more sites with native vegetation and fewer sites with exotic or degraded native vegetation being predicted suitable for A. parapulchella. Analysis of a relatively well-surveyed sub-area indicated that including agricultural modification led to slightly higher omission rates but markedly fewer likely false positives. Expert assessment of the model based on mapped habitat also suggested that including agricultural modification improved predictions. We estimate that agricultural modification has led to the destruction or decline of approximately 30–35% of the most suitable habitat in the sub-area studied and approximately 20–25% of suitable habitat across the entire study area, located in the Australian Capital Territory, Australia. Environmental niche models for a range of species, particularly habitat specialists, are likely to benefit from incorporating agricultural modification. Our findings are therefore relevant to threatened species planning and management, particularly at finer spatial scales.