EvoDevo and its significance for animal evolution and phylogeny

Abstract

Despite Steinböck’s (1963, p. 49) dismissive statement that “ontogeny has only a very limited value for phylogenetic questions,” successful attempts to infer phylogenetic relationships from comparative information about the developmental schedules of animal species are numerous, beginning with two well-known, eighteenth-century examples. One is Thompson’s (1830) discovery of the crustacean nature of barnacles, based on his observation of nauplius larvae metamorphosing into sessile adults (see Chap. XX) whose morphology deviates so strongly from the arthropod ground plan that Linné (1758) placed Lepas (inclusive of barnacles) in his Vermes Testacea (i.e., the shelled mollusks) rather than in his Insecta (a “class” broadly equivalent to present-day Arthropoda). The other example is Kowalewski’s (1866) discovery of the affinities between vertebrates and ascidians, revealed by the presence of the notochord in the larva of the latter (Chap. XX). This does not imply, however, that the relationships between ontogeny and phylogeny are always easy to discover or that these follow simple and perhaps universal principles such as Haeckel’s (1866) “biogenetic law.” Haeckel’s recapitulationist views, indeed, have never been again much in favor since Garstang (1922) demonstrated that many larval adaptations are recent and independent; and a further strong blow to the theory was de Beer’s (1930, 1940) demonstration of the pervasiveness of heterochrony. However, new opportunities to extract phylogenetic information from ontogenetic data have been emerging since the advent of evolutionary developmental biology (Telford and Budd 2003; Cracraft 2005; Minelli 2007, 2009; Minelli et al. 2007).