Developmental evolution as a mechanistic science: The inference from developmental mechanisms to evolutionary processes

SYNOPSIS. Developmental Evolution (DE) contributes to various research prog rams in biology, such as the assessment of homology and the determination o f the genetic architecture underlying species differences. The most distinc tive contribution offered by DE to evolutionary biology, however, is the el ucidation of the role of developmental mechanisms in the origin of evolutio nary innovations. To date, explanations of evolutionary innovations have re mained beyond the reach of classical evolutionary genetics, because such ex planations require detailed information on the function of genes and the em ergent developmental dynamics of their interactions with other genetic fact ors. We argue that this area has the potential to become the core of DE's d isciplinary identity. The main challenge in developing a research program f or DE along these lines, however, is to provide a methodological framework that accounts for the fact that developmental mechanisms continue to evolve after a character has originated. Developmental mechanisms elucidated in a derived species may therefore not provide insights into the evolutionary o rigin of the character in question. To meet this challenge, we propose a se t of questions that may guide us in our search for valid inferences on the role of developmental mechanisms in the explanation of evolutionary innovat ions.