Mining the Most Species-Rich Amniote Genus: de novo Sequencing of Three Anole Lizards for Comparative Genomic Analysis

The repeated evolution of morphological adaptations to specific ecological niches makes Anolis lizards a spectacular example of adaptive radiation in vertebrates, and an ideal model for comparative genomics. The complete genome of the green anole (A. carolinensis) has already provided insights to the evolution of genomic and phenotypic variation in vertebrates. A multi-species comparison within the Anolis genus would increase the power of studies seeking to understand the genomic bases of species diversification. We carried out de novo whole genome sequencing and draft assembly of three species, the grass anole (A. auratus), the bridled anole (A. frenatus), and the slender anole (A. apletophallus). Here we report some of our preliminary comparative genomic findings. Analysis of the abundance and diversity of transposable elements within these genomes has revealed repetitive landscapes typical of non-mammalian vertebrates, yet variation between Anolis species is greater than what is observed across most mammals. This may have provided a genomic environment amenable to key adaptations during the Anolis radiation. Using well-defined models such as mouse and chicken, we identified orthologous genes integral to myogenesis and limb development, and are beginning to catalogue interspecific variation in protein-coding genes and cis-regulatory motifs. Functional anatomical and histological studies are being performed to quantify the tail and hindlimb muscle groups of these species compared to A. carolinensis. Our ultimate goal is to identify the divergent alleles associated with ecological speciation, thus bridging the genotype-phenotype gap.