VIEWS FROM UNDERSTANDING EVOLUTION A Name by Any Other Tree

If you read other articles in this issue carefully, you might begin to wonder if animal life is going through a hushed up identity crisis: Hummingbirds and canaries have finally come out as dinosaurs (Angielczyck 2009; Chiappe 2009). Despite lacking the four feet of tetrapods (tetra = four, pod = foot), snakes and whales have been embraced by this group (Clack 2009). Elephants are simply confused; they may or may not be ungulates (Prothero 2009). This taxonomic soul searching and the resulting strange bedfellows (e.g., lumping budgies with brachiosaurus) do not, of course, stem from long therapy sessions, but from a quiet revolution gripping biology: phylogenetics. Phylogenetics is the area of biology that deals with evolutionary relationships among organisms. In the past few decades, technological advances have produced a flood of genetic data, computing power has exploded, and scientists have developed new mathematical algorithms for building phylogenies—or evolutionary trees. As a result, biologists have been increasingly able to reconstruct the evolutionary histories of groups of organisms. We can now draw the family trees of close-knit groups, like Darwin’s finches (Petren et al. 1999), and sketch the deepest lines of descent that connect animals, plants, fungi, and bacteria (Ciccarelli et al. 2006; Figs. 1 and 2). The widespread availability of evolutionary trees is reshaping how biologists ask and answer biological questions. For a review of how to read and understand evolutionary trees, see Gregory (2009). Phylogenies have even invaded what is, perhaps, the most foundational area of biology: taxonomy—how we classify and name life forms. This is the reason that elephants are left on the fence about their identity, while birds have landed in the dinosaur camp, and snakes can boast the paradoxical title of tetrapod. Biologists have changed the fundamental ways that they think about classification.