Global warming, body size and conservation in a Qinghai-Tibet Plateau lizard

Global mean temperatures have increased by 0.3–0.6°C since the late 19th century, affecting the physiology, distributions, phenology and adaptations of plants and animals. In the Qinghai-Tibet Plateau, average annual temperatures increased by an average of 0.25°C per decade from the 1970s to the 1990s, and by an average of 0.34°C per decade thereafter. Using museum collections from the 1950s to the 2000s and published references, we tested the hypothesis that body size of the toad-headed lizard Phrynocephalus vlangalii in the Qinghai-Tibet Plateau declined between 1954 and 2008 as a response to global warming. However, body size of males and females did not vary significantly between 1954 and 2008, probably due to the reciprocity between higher food availability and earlier age at sexual maturity. We suggest that human activity might result in declining population sizes in the future despite the lack of an apparent current response to changing climates.