Proc. R. Soc. B http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2011.2000 (2011)

Credit: © MAGESOURCE

For ectotherms — cold-blooded animals, including reptiles and amphibians, which cannot regulate their temperature through their own metabolism — environmental temperature changes “literally change the pace of life,” according to Wenyun Zuo, of the University of New Mexico in Albuquerque, and colleagues.

Ectotherms develop from infancy to adulthood more quickly in warmer conditions, and increase their body mass faster too. Most ectotherms follow a temperature-size rule, whereby the warmer the temperature, the smaller the animal is at maturity. But for about 15% of species, the reverse holds: the warmer it is, the larger they get.

Zuo's team explains this oddity with a simple mathematical model, in which the rate of biomass accumulation and the pace of maturity have different temperature dependences. The usual size rule applies for those animals in which temperature has a stronger affect on development rate than on body mass accumulation. The model shows that these animals not only mature more quickly at warmer temperatures, but also use less energy to do so, giving them an evolutionary advantage in most conditions. Their model could be used to predict the effects of climate change on various species' body sizes, the authors say.