Quantifying the effects of embryonic phenotypic plasticity on adult phenotypes in reptiles: A review of current knowledge and major gaps

Studies of reptiles have contributed greatly to understanding the impacts of developmental environments on offspring phenotypes. A major challenge for these studies, however, is quantifying the effects of embryonic environments on adult phenotypes and reproductive success. Such measurements may be necessary to gain full insight into the evolution of plasticity, as well as the long-term consequences of plasticity under environmental change. Unfortunately, most studies of reptile developmental plasticity only measure phenotypic traits of offspring at hatching, and rarely evaluate effects on subsequent adult phenotypes. This lack of information highlights a major gap in this active field. In this review, we first discuss conceptual issues regarding the ecology and evolution of plasticity to provide justification for long-term studies necessary to measure adult phenotypes. Second, we review case studies of reptiles that assessed the effects of developmental environments on adult phenotypes and/or reproduction, and we highlight the valuable insights that they provide. Importantly, we illustrate that terminating studies during early-life stages can lead to incomplete or even misleading interpretations. Third, we discuss the pros and cons of different experimental approaches for quantifying long-term effects of developmental environments. Overall, devoted long-term studies on taxa with diverse ecologies and life histories will provide major advances in the field of developmental plasticity.