Meeting Abstract
The first phase of the crocodilian genome project has been completed. We sequenced and assembled the genomes of the American alligator, Saltwater crocodile, and Indian gharial. One striking feature of the crocodilian genomes is that they seem to evolve very slowly. To test the hypothesis of slow molecular evolution in crocodilians, we wanted to compare a relatively large number of single-copy orthologous loci from species throughout the tetrapod tree of life. Previously, we had used ultraconserved elements (UCEs) to obtain such loci for phylogenetic studies by extracting UCEs from sequenced genomes or by using sequence capture probes to amniote UCEs. In this study, we used UCEs to directly compare the rates of molecular evolution of crocodilians to all other major groups of tetrapods. We found that crocodilians do have slow rates of molecular evolution at UCE loci (i.e., the UCEs plus flanking DNA) and that analyses of other portions of the genome reveal similar results. Because unique sets of UCEs are known in many broad phylogenetic groups containing thousands of species (tetrapods, fish, and hymenoptera), and are likely in many other such groups, UCEs represent unique portals into the genomes of the diverse array of organisms studied by SICB members.
