Reconstructing animal phylogeny in the light of evolutionary developmental biology

The relevance of evolutionary developmental biology (evo-devo) in our effort to reconstruct the tree of life has been very poorly explored until recently. However, the contribution of an evo-devo approach to the main steps of phylogenetic analysis, such as evaluation of homology, selection of characters and assessment of character polarity can be critically important, especially in species-rich groups. As independence of traits is a prerequisite for the use of coded information in the reconstruction of phylogeny, the identification of developmentally independent units is one of the areas where evo-devo biology may offer an especially important contribution. The way in which characters originate and change in evolution has fundamental consequences on the patterns of evolutionary change we can reconstruct from character distribution. The remoulding of pre-existing features, genetic networks, or developmental trajectories, can operate at any level of biological organisation. Comparative developmental biology supports a view that homology cannot be a relationship of the all-or-nothing kind.