The Temperature‐Size Rule in Ectotherms: Simple Evolutionary Explanations May Not Be General

In many organisms, individuals in colder environments grow more slowly but are larger as adults. This widespread pattern is embodied by two well-established rules: Bergmann's rule, which describes the association between temperature and body size in natural environments, and the temperature-size rule, which describes reaction norms relating temperature to body size in laboratory experiments. Theory predicts that organisms should grow to be larger in colder environments when growth efficiency decreases with increasing environmental temperature. Using data from 97 laboratory experiments, including 58 species of ectotherms, we found little evidence that growth efficiency is negatively related to environmental…

• IS
  Indiana State University