Mismatch Between Ectotherm Thermal Preferenda and Optima for Swimming: A Test of the Evolutionary Pace Hypothesis

摘要

A continuing issue in evolutionary thermal biology is the mismatch between preferred body temperatures (T pref) and optimal temperatures (T opt) for whole-animal performance. Using phylogenetic comparative analyses, I examined the hypothesis that a difference in the rates at which T pref and T opt evolve causes the mismatch in a lineage of European newts. In a laboratory thermal gradient, newts maintained body temperatures that were on average 8 °C below T opt for maximum swimming velocity. The lower boundary of the T pref range evolved faster than the mean T pref, the upper boundary of the T pref range, and T opt. The strong evolutionary co-variation between mean T pref and its boundaries prevented the shift of mean T pref away from T opt. This suggests that the variation in evolutionary rates has a limited potential to modify the disparity between thermal optima and preferenda.