The critical thermal limits of organisms and the thermal sensitivity of their performance tend to vary predictably across latitudinal gradients. There has been comparatively less investigation into variation in thermal biology with elevation, despite similar gradients in environmental temperatures. To redress this, we examined critical thermal limits (CTmin and CTmax), thermal sensitivity of locomotor performance, and shelter site attributes, in three lizard species that replace one another along a contiguous elevation gradient in south-eastern Australia. The species examined consisted of a highland specialist, Liopholis guthega, mid-elevation species, Liopholis montana, and lowland species, Liopholis whitii. We found similar habitat attributes between the species, but L. guthega predominantly occurred in open habitat, which might reflect a strategy for maximizing exposure to insolation. We found intraspecific variation in lizard thermal traits, most notably in cold tolerance of L. guthega and in both heat and cold tolerance of L. whitii, suggesting population-specific variables acting on thermal physiology rather than a species distribution maintained by distinct thermal tolerances. This study represents one of the few examinations of thermal trait variability within and between species with elevation in a temperate system and provides evidence for thermal physiology driven by adaptation and/or physiological plasticity to local conditions.

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Anthropogenic climate change is causing a world-wide reduction of alpine habitat, leaving many high-elevation species restricted to sky-islands and vulnerable to extinction. Understanding the genetic parameters of these populations provides key insight into species diversity, dispersal capacity and vulnerability to disturbance. We examined the impact of past climatic variation on a threatened alpine endemic lizard, the Guthega skink, Liopholis guthega. We analysed SNP and mtDNA data to determine the population structure and phylogeny within this species, providing an understanding of the species' relatedness, dispersal and viability. We identified significant genetic structure, with the split between populations in Koscuiszko National Park, New South Wales (NSW) and the Bogong High Plains, Victoria (VIC) consistent with Plio-Pleistocene divergence. However, we also detected evidence of possible historical introgressive hybridization between some NSW populations and the VIC populations. Marked within-site population structure and significant population differentiation among sites within each state were found, indicating a limited dispersal capacity. Higher levels of genetic diversity within NSW support the correlation between elevation and diversity and implicate Kosciuszko National Park as a historic refugia. Low contemporary habitat availability, little to no capacity for elevational progression and low genetic diversity, particularly in VIC, leaves L. guthega highly vulnerable to threatening processes associated with climate change. Conservation management should consider genetic rescue as a potential method to enhance genetic diversity across this species' range.

A species' life history is a strong determinant of its risk of extinction; traits such as body size, growth rate, age at maturity and fecundity influence population viability and persistence, as well as capacity for dispersal and colonisation of new habitats. Yet, despite the potential for substantial geographic variation in life history, most conservation programmes rely upon the species average rather than information specific to individual populations. We use the Guthega Skink (Liopholis guthega), a threatened alpine endemic lizard restricted to two geographically isolated locations in southeastern Australia, as a case study to demonstrate how geographic variation in life history traits may better inform conservation management. Liopholis guthega has a relatively short life span, with only a few years of reproductive activity, inter-annual variation in reproductive output, and less-than-annual reproduction. We show that the Victorian population has a significantly slower growth rate, attains a smaller maximum size, reaches reproductive maturity later, and produces significantly smaller litters, despite no difference in longevity suggesting that it may be more vulnerable to extinction. We, therefore, suggest evaluating genetic rescue from the New South Wales population to improve recruitment and longevity of Victorian L. guthega, ongoing population monitoring in both locations, and a dedicated pest control programme to reduce pressure on this population. Our study has far reaching impacts; primarily demonstrating how knowledge of geographic variation in life history has the potential to improve conservation management of threatened species.

Phenotypic variation provides the framework for natural selection to work upon, enabling adaptive evolution. One of the most discernible manifestations of phenotypic variability is colour variation. When this variation is discrete, genetically based colour pattern morphs occur simultaneously within a population. Why and how colour polymorphisms are maintained is an evolutionary puzzle. Several evolutionary drivers have been hypothesized as influencing clinal patterns of morph frequency, with spatial variation in climate and predation being considered especially important. Despite this, no study has examined both of their roles simultaneously. The aims of this study were to: (a) examine the covariation of physiology, environmental variables and colouration at a local scale; and (b) determine if these factors and their interplay explain broad clinal variation in morph frequency. We used the lizard Liopholis whitii as a model system, as this species displays a discrete, heritable polymorphism for colour pattern (plain-backed, patterned morphs) whose morph frequency varies latitudinally. We measured reflectance, field activity temperatures and microhabitat structure to test for differences in crypsis, thermal biology and microhabitat selection of patterned and plain-backed morphs within a single population where colour morphs occur sympatrically. We then used data from the literature to perform a broad-scale analysis to identify whether these factors also explained the latitudinal variation of morph frequency in this species. At the local scale, plain-backed morphs were found to be less cryptic than patterned morphs while no other differences were detected in terms of thermal biology, dorsal reflectance and microhabitat use. At a broader scale, predation was the most influential factor mediating morph frequency across latitudes. However, the observed pattern of morph frequency is opposite to what the modelling results suggest in that the incidence of the least cryptic morph is highest where predation pressure is most severe. Clinal variation in the level of background matching between morphs or the potential reproductive advantage by the plain-backed morph may, instead, be driving the observed morph frequency. Together, these results provide key insights into the evolution of local adaptation as well as the ecological forces involved in driving the dynamics of colour polymorphism.