Measuring the plasticity of developmental rate across insect populations: comment on Rocha and Klaczko (2012)

Rocha and Klaczko emphasize the general complexity of reaction norm shape and caution that ignoring such complexity can be misleading when forcing nonlinear reaction norms into linear shapes. They refer to our article on differences in plasticity of Drosophila serrata populations along a latitudinal gradient as an example of a misleading simplifying approach. However, their claim that an artifact is introduced into our analyses by calculating developmental rate as the reciprocal of development time (rate = time(-1)) is based on a misunderstanding of the mathematical properties of the thermal developmental rate reaction norm. Here we discuss why developmental rate is a suitable measure for our study and under which circumstances it is appropriate to describe developmental rate by a linear model.