Is Heterochrony Still an Effective Paradigm for Contemporary Studies of Evo-devo?

Abstract

Heterochrony, or change in the relative timing of developmental events, has been a dominant concept in the study of the relation between evolution and development since even before the term was coined in the mid-nineteenth century. Its popularity exploded beginning in the late 1970s and 1980s as part of the resurgence of interest in Evo-devo that also began at that time, and reflecting a basic premise that heterochronic analysis is indispensible to a meaningful understanding and explanation of morphological diversification. Yet the gradual recognition that the molecular and developmental mechanisms that underlie morphological evolution may be understood more effectively in terms of other processes has increasingly qualified the universality of heterochrony as an explanatory tool. Consequently, while heterochrony still has an important role to play in contemporary studies of Evo-devo, it is not an all-encompassing and exclusive role. Instead, a more nuanced view of heterochrony—as an important paradigm, but not the sole paradigm—provides a more comprehensive depiction and understanding of the developmental basis of evolutionary change.