From genomes to morphology: A view from amphioxus
As complete genome sequences are determined from an ever-increasing number of animal species, new opportunities are arising for comparative biology. For zoologists interested in the evolution of shape and form, however, there is a problem. The link between genome sequence and morphology is not direct and is obfuscated by complex and evolving genetic pathways, even when conserved regulatory genes are considered. Nonetheless, a large-scale comparison of genome sequences between extant chordates reveals an intriguing parallel between genotypic and phenotypic evolution. Tunicates have highly altered genomes, with loss of ancestral genes and shuffled genetic arrangements, while vertebrate genomes are also derived through gene loss and genome duplication. The recently sequenced amphioxus genome, in contrast, reveals much greater stasis on the cephalochordate lineage, in parallel to a less derived body plan. The opportunities and challenges for relating genome evolution to morphological evolution are discussed. © 2010 The Royal Swedish Academy of Sciences.