Adaptive trans-generational phenotypic plasticity and the lack of an experimental control in reciprocal match/mismatch experiments

Abstract

Parental information about the prevailing environmental condition may enable offspring to adjust their phenotypes in accordance with future demands. The state-of-the-art experimental test of the occurrence of such adaptive trans-generational phenotypic plasticity is a ‘match/mismatch’ approach: a fully factorial reciprocal transplant experiment where offspring encounter environments either matching or mismatching parents’ experience. Here, we highlight that a hidden assumption of this approach is that the effect of early and late offspring environment acts completely additively on offspring fitness. Likely violations of this assumption, such that early ‘silver-spoon’ effects are more valuable when later environmental conditions are relatively harsh, will bias the estimates of potential trans-generational effects. We discuss the different implications of this on the interpretation of the outcome of match/mismatch experiments and suggest different complementary and alternative approaches.