A general rule for the dependence of developmental rate on temperature in ectothermic animals.

In animals that do not regulate their body temperature by the production of heat, the proportion of the total developmental time spent in a particular developmental stage does not change with temperature. In the quasi-linear region of the relationship between developmental rate and temperature, all of the developmental stages appear to have the same species-specific lower developmental threshold. This trait, which is called developmental isomorphy, constrains developmental adaptations of ectotherms to their environments and facilitates the precise timing of life-history events.