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It is predicted that climate change will cause species extinctions and distributional shifts in coming decades, but data to validate these predictions are relatively scarce. Here, we compare recent and historical surveys for 48 Mexican lizard species at 200 sites. Since 1975, 12% of local populations have gone extinct. We verified physiological models of extinction risk with observed local extinctions and extended projections worldwide. Since 1975, we estimate that 4% of local populations have gone extinct worldwide, but by 2080 local extinctions are projected to reach 39% worldwide, and species extinctions may reach 20%. Global extinction projections were validated with local extinctions observed from 1975 to 2009 for regional biotas on four other continents, suggesting that lizards have already crossed a threshold for extinctions caused by climate change. 10.1126/science.1184695

As a group, lizards occupy a vast array of habitats worldwide, yet there remain relatively few cases where habitat use (ecology), morphology, and thus, performance, are clearly related. The best known examples include: increased limb length in response to increased arboreal perch diameter in anoles and increased limb length in response to increased habitat openness for some skinks. Rocky habitats impose strong natural selection on specific morphological characteristics, which differs from that imposed on terrestrial species, because moving about on inclined substrates of irregular sizes and shapes constrains locomotor performance in predictable ways. We quantified habitat use, morphology, and performance of 19 species of lizards (family Scincidae, subfamily Lygosominae) from 23 populations in tropical Australia. These species use habitats with considerable variation in rock availability. Comparative phylogenetic analyses revealed that occupation of rock-dominated habitats correlated with the evolution of increased limb length, compared to species from forest habitats that predominantly occupied leaf litter. Moreover, increased limb length directly affected performance, with species from rocky habitats having greater sprinting, climbing, and clinging ability than their relatives from less rocky habitats. Thus, we found that the degree of rock use is correlated with both morphological and performance evolution in this group of tropical lizards. Key words: adaptation; comparative method; ecomorphology; habitat use; lizard; locomotion; performance; physiological ecology; rock use; Scincidae.

We surveyed electrophoretic variation and examined population structuring in the endangered Black-capped Vireo (Vireo atricapillus), a species whose distribution is closely tied with a successional habitat. Seventeen presumptive loci were resolved from blood from individuals in four populations in Texas and Oklahoma. Mean heterozygosity in the Black-capped Vireo was 0.058. A significant departure from random mating expectations was detected in only 1 of 26 comparisons. Highly significant differentiation was observed among populations (mean [theta] = 0.17). Although the high levels of differentiation suggest limited exchange between populations, most of the differentiation was due to divergence at two loci. The relatively high heterozygosity and the association with successional habitats suggest a source-sink population dynamic with new habitat patches colonized from several source populations. Our results suggest that management of this species should focus on its habitat preferences and conserving connectivity between patches rather than on concerns of loss of heterozygosity. Key words: allozymes, endangered, genetic variation, Vireo atricapillus.

Free-ranging lizards have been studied relative to their locomotor performance, reproductive burden, and the cost of reproduction. The change in endurance between gravid and postgravid side-blotched lizards, Uta stansburiana, was measured to find the cost of reproduction. Reproductive investment was changed in some females by direct ovarian manipulation. All females had lower endurance when gravid. Analyses showed the decrement in performance associated with current reproductive investment represents a cost of reproduction expressed as diminished locomotor performance and lowered survivorship at the next clutch.

Research demonstrates the key role of the environment in biological morphology, using lizard genera Anolis and Sceloporus as examples. Topics include a comparison of morphological traits, such as limb proportions and tail length, and of geographic location, such as tropic and arid, for both species.

Most analyses of adaptation employ a comparison among taxa for resolving correlations between a trait and a suite of environmental variables. Inferences regarding the evolution of a trait may be [...]

Models of global climate change predict an increase in the mean surface temperature between 1.5 [degrees] and 4.5 [degrees] C by the middle of the next century. Even a moderate increase of 3 [degrees] C is likely to result in a shift in the distribution of North American habitat types and vegetational associations, either in latitude or elevation or both. The challenge to Conservation Biology is to predict the responses of terrestrial organisms to the expected alteration in habitats and ecosystems. Recent biophysical models have been expanded to demonstrate the intimate associations between the thermal environment, organismal physiology and ecology. Thus, the expected turnover in habitats may have a profound influence on the distribution of organisms. I describe one possible approach that couples temporal and spatial variation in an ecologically relevant physiological trait, locomotory performance, in a widespread species of lizard, Urosaurus ornatus, to predict the expected response of species to global change. Estimates of maximum velocity and endurance capacity were obtained from 16 populations throughout the range of U. ornatus. Information on spatial variation was supplemented with data on temporal variation spanning an eight year period from a single reference population. I used these data to address two questions: 1) is there an association between locomotory performance and the expected habitat changes predicted from global climate models and 2) is there sufficient variation within a population to respond to habitat modification. Populations of U. ornatus varied significantly in sprint speed and stamina. Several environmental factors expected to correlate with global climate change were evaluated using the patterns of variation in locomotor performance. Results from this study suggest that high elevation populations found in ponderosa pine forests should be most susceptible to changes in climate. Within-population variation was found to span the range of variation seen among populations and was sensitive to temporal variation in climatic conditions. Given the expected and rapid change in environments, small, ectothermic, terrestrial species may not have the ability to modify their geographic distribution. However, the results presented here suggest that only certain populations are at risk; yet the evolutionary response of the population may be long relative to the rate of environment change.

A method was devised to identify the variations in life history traits that are due to phylogenetic effects. First, the taxonomic level at which most of the variation is associated was evaluated by nested ANCOVAs. An intraclass correlation coefficient, which measures the differences among descendant taxa at any given level, was subsequently calculated. Finally, a network autocorrelation method was used to map the species' life history attributes onto their evolutionary relationships, thus showing variation patterns that are explainable in terms of phylogenetic interrelationships.

The natural world displays a bewildering variety of organisms that appear uniquely adapted to a myriad of environmental conditions. In seeking to disentangle the basis for this diversity, evolutionary biologists [...]