Published online by Cambridge University Press: 31 May 2012
Gilbert and Raworth (1996) propose a general theory to explain the effects of temperature on the development and growth rates of insects. The theory is evolutionary rather than physiological. They propose that insects are selected for a high rate of increase (i.e., rapid growth and large size) in spring, and for rapid development in summer. They claim that these selection pressures explain five “puzzles:” (1) the linearity of the relationship between development rate and temperature, (2) a reduction in the genetic variation of development rate at high temperature (i.e., average midsummer temperature), (3) a reduction in the genetic variation of growth rate at low temperature (i.e., average spring temperature), (4) slow development at the time of emergence after overwintering, and (5) a greater reduction in development rate than growth rate at low temperature.