The mesic habitats of eastern Australia harbour a highly diverse fauna. We examined the impact of climatic oscillations and recognised biogeographic barriers on the evolutionary history of the ...delicate skink (Lampropholis delicata), a species that occurs in moist habitats throughout eastern Australia. The delicate skink is a common and widespread species whose distribution spans 26° of latitude and nine major biogeographic barriers in eastern Australia. Sequence data were obtained from four mitochondrial genes (ND2, ND4, 12SrRNA, 16SrRNA) for 238 individuals from 120 populations across the entire native distribution of the species. The evolutionary history and diversification of the delicate skink was investigated using a range of phylogenetic (Maximum Likelihood, Bayesian) and phylogeographic analyses (genetic diversity, ΦST, AMOVA, Tajima's D, Fu's F statistic).
Nine geographically structured, genetically divergent clades were identified within the delicate skink. The main clades diverged during the late Miocene-Pliocene, coinciding with the decline and fragmentation of rainforest and other wet forest habitats in eastern Australia. Most of the phylogeographic breaks within the delicate skink were concordant with dry habitat or high elevation barriers, including several recognised biogeographic barriers in eastern Australia (Burdekin Gap, St Lawrence Gap, McPherson Range, Hunter Valley, southern New South Wales). Genetically divergent populations were also located in high elevation topographic isolates inland from the main range of L. delicata (Kroombit Tops, Blackdown Tablelands, Coolah Tops). The species colonised South Australia from southern New South Wales via an inland route, possibly along the Murray River system. There is evidence for recent expansion of the species range across eastern Victoria and into Tasmania, via the Bassian Isthmus, during the late Pleistocene.
The delicate skink is a single widespread, but genetically variable, species. This study provides the first detailed phylogeographic investigation of a widespread species whose distribution spans virtually all of the major biogeographic barriers in eastern Australia.
The Red List of Threatened Species, published by the International Union for Conservation of Nature (IUCN), is a crucial tool for conservation decision-making. However, despite substantial effort, ...numerous species remain unassessed or have insufficient data available to be assigned a Red List extinction risk category. Moreover, the Red Listing process is subject to various sources of uncertainty and bias. The development of robust automated assessment methods could serve as an efficient and highly useful tool to accelerate the assessment process and offer provisional assessments. Here, we aimed to (1) present a machine learning-based automated extinction risk assessment method that can be used on less known species; (2) offer provisional assessments for all reptiles-the only major tetrapod group without a comprehensive Red List assessment; and (3) evaluate potential effects of human decision biases on the outcome of assessments. We use the method presented here to assess 4,369 reptile species that are currently unassessed or classified as Data Deficient by the IUCN. The models used in our predictions were 90% accurate in classifying species as threatened/nonthreatened, and 84% accurate in predicting specific extinction risk categories. Unassessed and Data Deficient reptiles were considerably more likely to be threatened than assessed species, adding to mounting evidence that these species warrant more conservation attention. The overall proportion of threatened species greatly increased when we included our provisional assessments. Assessor identities strongly affected prediction outcomes, suggesting that assessor effects need to be carefully considered in extinction risk assessments. Regions and taxa we identified as likely to be more threatened should be given increased attention in new assessments and conservation planning. Lastly, the method we present here can be easily implemented to help bridge the assessment gap for other less known taxa.
Reptiles are the most species-rich group of terrestrial vertebrates, yet we lack a comprehensive understanding of their extinction risk. Only 45% of described reptile species have been assessed by ...IUCN to date (4648 of 10,400 species); of these, 20% (945 species) are threatened with extinction, and 19% (867 species) are Data Deficient. The goal of this special issue is to improve our understanding of reptile conservation needs and extinction risk by (i) investigating patterns and drivers of extinction risk and data deficiency at a global scale; (ii) identifying and addressing taxonomic and regional gaps in our understanding of extinction risk and data deficiency; and (iii) drawing upon detailed case studies to highlight conservation approaches to mitigate extinction. By doing so, the special issue will guide future conservation efforts toward the taxa and regions in greatest need of assessment, and toward risks requiring immediate mitigation. We conclude with potential avenues for future research, including the need to address regional knowledge gaps, conduct macroecological and retrospective analyses of extinction risk, and implement targeted monitoring of conservation intervention outcomes.
Reptiles represent the world's most diverse group of terrestrial vertebrates (~10,300 recognized species). Knowledge of their conservation status, however, lags behind that of birds, mammals and ...amphibians. Only ~40% of the world's reptile species have had their conservation status assessed by the IUCN, and detailed analysis of extinction risk has been limited to a subset of 1500 species. Using lizards (Sauria and Amphisbaenia), the most diverse group of reptiles, we investigated whether biases in distribution, ecology, life-history and taxonomy exist in the species that have been assessed to date by the IUCN. Our results highlight that only 36% of the ~6300 described lizard species have had their conservation status assessed. Whilst data deficiency is a key concern in lizards (16% of assessed species), the large number of non-assessed species (~4000 species) represents a larger and more pressing issue. Accentuating this ‘assessment gap’ is the fact that biases exist in the subset of lizard species that have been assessed by the IUCN. Australia and Asia, as well as tropical areas in general, were the least assessed regions. Assessed lizard species were more likely to have larger body and clutch sizes, broader distributional and elevational ranges, occur at more northerly latitudes, and have a viviparous mode of reproduction. Some evidence suggests that they also tend to be diurnal, surface active, and with developed limbs. The level of assessment also differed significantly among lizard families and higher taxa. We recommend the implementation of an integrated approach to bridge the ‘assessment gap’ in lizards, involving regional and taxon-specific working groups associated with the IUCN's Global Reptile Assessment, predictive modelling, enhanced knowledge of lizard distribution and biology, and improved taxonomic methods.
Abstract Trait polymorphisms can vary across different contexts of selection and be maintained through trade-offs between these contexts. For example, colour polymorphic variants may represent ...alternative strategies optimizing crypsis or thermoregulation in different populations. Here we use visual modelling to test the conspicuousness of different colour pattern morphs in males and females of an Australian lizard, Lampropholis delicata, to predators and conspecifics. We further assess differences in reflectance, microhabitat selection, and mate preference to determine the functional role of the polymorphism and explain its variable distribution across latitude and the sexes. Plain morphs are more conspicuous than striped morphs in both bird and lizard visual models, suggesting predation selection, and habitat structure varies among sex-morph types, but we find no difference in microhabitat selection or mate preference based on colour. We suggest that a combination of spatially varying selection, habitat preference, and context-specific behaviour may be necessary to explain spatial patterns of colour morph frequencies.
Unintentional species invasions are instigated by human-mediated dispersal of individuals beyond their native range. Although most introductions fail at the first hurdle, a select subset pass through ...each stage of the introduction process (i.e. transport, introduction, establishment and spread) to become successful invaders. Efforts to identify the traits associated with invasion success have predominately focused on deliberate introductions, which essentially bypass the initial introduction stage. Here, we highlight how behavior influences the success or failure of unintentional species introductions across each stage of the introduction process, with a particular focus on transportation and initial establishment. In addition, we emphasize how recent advances in understanding of animal personalities and individual-level behavioral variation can help elucidate the mechanisms underlying the success of stowaways.
Protected Areas (PAs) are the cornerstone of biodiversity conservation. Here, we collated distributional data for >14,000 (~70% of) species of amphibians and reptiles (herpetofauna) to perform a ...global assessment of the conservation effectiveness of PAs using species distribution models. Our analyses reveal that >91% of herpetofauna species are currently distributed in PAs, and that this proportion will remain unaltered under future climate change. Indeed, loss of species' distributional ranges will be lower inside PAs than outside them. Therefore, the proportion of effectively protected species is predicted to increase. However, over 7.8% of species currently occur outside PAs, and large spatial conservation gaps remain, mainly across tropical and subtropical moist broadleaf forests, and across non-high-income countries. We also predict that more than 300 amphibian and 500 reptile species may go extinct under climate change over the course of the ongoing century. Our study highlights the importance of PAs in providing herpetofauna with refuge from climate change, and suggests ways to optimize PAs to better conserve biodiversity worldwide.
Studies of realized niche shifts in alien species typically ignore the potential effects of intraspecific niche variation and different invaded‐range environments on niche lability. We incorporate ...our detailed knowledge of the native‐range source populations and global introduction history of the delicate skink Lampropholis delicata to examine intraspecific variation in realized niche expansion and unfilling, and investigate how alternative niche modelling approaches are affected by that variation. We analyzed the realized niche dynamics of L. delicata using an ordination method, ecological niche models (ENMs), and occurrence records from 1) Australia (native range), 2) New Zealand, 3) Hawaii, 4) the two distinct native‐range clades that were the sources for the New Zealand and Hawaii introductions, and 5) the species’ global range (including Lord Howe Island, Australia). We found a gradient of realized niche change across the invaded ranges of L. delicata: niche stasis on Lord Howe Island, niche unfilling in New Zealand (16%), and niche unfilling (87%) and expansion (14%) in Hawaii. ENMs fitted to native‐range data generally identified suitable climatic conditions at sites where the species has established non‐native populations, whereas ENMs based on native‐range source clades and non‐native populations had lower spatial transferability. Our results suggest that the extent to which realized niches are maintained during invasion does not depend on species‐level traits. When realized niche shifts are predominately due to niche unfilling, fully capturing species’ responses along climatic gradients by basing ENMs on native distributions may be more important for accurate invasion forecasts than incorporating phylogenetic differentiation, or integrating niche changes in the invaded range.
•Understanding the factors that determine extinction risk is vital for effective conservation.•Relative to other vertebrate groups, extinction risk has rarely been examined in reptiles.•We conduct ...the most comprehensive study of extinction risk within a reptile group.•Body size, geographic range size and habitat specialization were the strongest predictors of extinction risk.•We place our results in context with studies on extinction risk in other vertebrate groups.
A species’ vulnerability to extinction depends on extrinsic threats such as habitat loss, as well as its intrinsic ability to respond or adapt to such threats. Here we investigate the relative roles of extrinsic threats and intrinsic biological traits in determining extinction risk in the lizard fauna of New Zealand. Consistent with the results of previous studies on mammals and birds, we find that habitat specialization, body size and geographic range size are the strongest predictors of extinction risk. However, our analyses also reveal that lizards that occupy areas with high levels of annual rainfall and are exposed to exotic predators and high human population densities are at greater risk. Thus, while the intrinsic traits that render species prone to extinction appear largely congruent across vertebrate taxa, our findings illustrate that both extrinsic threats and intrinsic traits need to be considered in order to accurately predict, and hence prevent, future population declines.
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