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.

No abstract

Some biologists embrace the classical view that changes in behavior inevitably initiate or drive evolutionary changes in other traits, yet others note that behavior sometimes inhibits evolutionary changes. Here we develop a null model that quantifies the impact of regulatory behaviors (specifically, thermoregulatory behaviors) on body temperature and on performance of ectotherms. We apply the model to data on a lizard (Anolis cristatellus) and show that thermoregulatory behaviors likely inhibit selection for evolutionary shifts in thermal physiology with altitude. Because behavioral adjustments are commonly used by ectotherms to regulate physiological performance, regulatory behaviors should generally constrain rather than drive evolution, a phenomenon we call the "Bogert effect." We briefly review a few other examples that contradict the classical view of behavior as the inevitable driving force in evolution. Overall, our analysis and brief review challenge the classical view that behavior is invariably the driving force in evolution, and instead our work supports the alternative view that behavior has diverse-and sometimes conflicting-effects on the directions and rates at which other traits evolve. A shift into a new niche or adaptive zone is, almost without exception, initiated by a change in behavior. The other adaptations to the new niche, particularly the structural ones, are acquired secondarily. With habitat and food selection-behavioral phenomena-playing a major role in the shift into new adaptive zones, the importance of behavior in initiating new evolutionary events is self-evident. (E. Mayr [1963, p. 604 Keywords ])By behavior organisms can effectively damp out heterogeneity in the physical environment. … Indeed this dampening of external environmental heterogeneity seems to be one of the major trends of evolution. (R. N. Brandon [1988, p. 65]) Evolutionary biologists classically view behavior as an important pacemaker or driver of evolutionary change. Indeed, many argue that "behavioral drive" usually initiates evolutionary shifts in morphology, physiology, or ecology (Schmalhausen 1949;Mayr 1959Mayr , 1963Hardy 1965;Wyles et al. 1983;Plotkin 1988;Wcislo 1989) or that behavioral shifts often promote speciation (Lande 1981;West-Eberhard 1989;Boake 1994). Nevertheless, some other biologists-predominantly physiological and functional ecologists-note that behavior can sometimes inhibit rather than drive evolutionary change in other traits (Elton 1927;Bogert 1949;Bartholomew 1964;Hertz 1981;Hertz and Huey 1981;Coyne et al. 1983;Wake et al. 1983;Brandon 1988;Odling-Smee 1988;Aboitiz 1990;van Damme et al. 1990). These authors note that regulatory behaviors (e.g., behavioral thermoregulation) often dampen the impact of environmental variation on organisms, thereby minimizing the intensity of selection on other traits.Our purpose here is not to challenge the validity of the classical view (e.g., Mayr 1963) that behavior is an important driver of evolutionary change. Instead, our primary goal is...