Fig. 7
From: Evidence against tetrapod-wide digit identities and for a limited frame shift in bird wings
The evolution of digit gene expression in amniotes is highly dynamic. a A phylogeny of the taxa sampled by this study and schematic graphs summarizing the relative similarity of digits within limbs, where connections and line thickness reflect degree of similarity in gene expression profiles. b Schematic of a limited frame shift model for evolutionary origin of the avian wing in which the developmental identity of D1 was translocated to position D2. Alligator and chicken illustrations reproduced with permission by Michael Richardson. Anolis illustration by Sarah Werning without modification (license [https://creativecommons.org/licenses/by/3.0/])
