Genome duplication, extinction and vertebrate evolution

Vertebrate evolution has been punctuated by three episodes of widespread gene or genome duplication, which have been linked with the origin of vertebrates, gnathostomes and teleosts, respectively. These three events coincide with bursts of character acquisition and increases in phenotypic complexity, and many researchers have suggested a causal relationship between the two. However, this pattern is derived from data for living taxa only; we argue here that, when fossils are taken into account, bursts of character acquisition disappear and gen(om)e duplication in vertebrate phylogeny can no longer be correlated with the origin of body plans. If patterns of character acquisition or morphological gaps between higher taxa are a reflection of phenotypic complexity, then more inclusive data sets incorporating fossil taxa provide no support for hypotheses linking gen(om)e duplications and the evolution of complexity in vertebrates.