Erosion of Lizard Diversity by Climate Change and Altered Thermal Niches

Abstract

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.

The conservation status of the world’s reptiles

“…Recently reported local declines in snake and lizard populations (Cagle, 2008;Reading et al, 2010;Sinervo et al, 2010) suggest localised elevated extinction risks for both taxa. While we estimate that about one in five lizard species is threatened with extinction, only 12% of snakes were estimated to be threatened with extinction.…”

Evaluating within‐population variability in behavior and demography for the adaptive potential of a dispersal‐limited species to climate change

“…Common methods for future range predictions ignore both the constraints, such as movement rates, and the adaptive capacity that influence how species respond to changes in their environment (Kearney & Porter, 2009; Thomas, Cameron, & Green, 2004). Multiple pathways exist for species to respond to climate change: dispersing into new habitats, evolving in response to changing conditions, ameliorating stressors via phenotypic plasticity, or going locally extinct (Lande & Shannon, 1996; Parmesan, 2006; Sinervo et al., 2010). While there is evidence that some species may be able to track their climate niche through time (Tingley, Monahan, Beissinger, & Moritz, 2009), it is unclear how less mobile species will respond to changing conditions.…”

A System for Assessing Vulnerability of Species (SAVS) to Climate Change

“…Population variations and reproductive output are often associated with energetic tradeoffs related to climate (Franklin and others 2000). Even moderate changes to daily temperature or humidity levels can influence daily activity patterns and ultimately limit food intake, limit access to mates, or increase predation risk (Lueth 1941;Walsberg 2000;Sinervo and others 2010). Recent local extinctions in Mexican lizards were attributed to climate-induced changes to suitable foraging time (Sinervo and others 2010).…”

“…Crepuscular species may already be restrained in an active period and unable to shift to nocturnal or diurnal activities. Ectotherms may be more vulnerable, because they rely more on behavior to adjust to changes in ambient conditions (Kearny and others 2009;Sinervo and others 2010).…”