Developmental System Drift

Developmental System Drift (DSD) is an evolutionary phenomenon whereby the genetic underpinnings of a trait in a common ancestor diverge in descendant lineages even as the trait itself remains conserved. Evidence for DSD comes from both interspecies hybridizations and comparative developmental genetic studies. The widespread occurrence of DSD implies that developmental systems are constantly evolving, even in the absence of selection for morphological change. Similar implications have been found in studies of the genetics of hybrid inviability and infertility, which reflect divergence in complex developmental systems that are perpetually under strong selection in all taxa. Gene duplications and compensatory changes in proteins and gene regulatory networks have been proposed to be the key mechanisms that drive DSD. DSD has implications for phylogenetic inference and biological homology, experimental tests of interspecies conservation of gene function, and convergent evolution. The burgeoning data and methods of comparative genomics, genome editing, and systems biology promise to greatly enhance our understanding of the dynamics and mechanisms of DSD.