Anole evolution

Green Anole (Anulis carolinensis)

Squamates include all lizards and snakes, and display some of the most diverse and extreme morphological adaptations among vertebrates. However, compared with birds and mammals, relatively few resources exist for comparative genomic analyses of squamates, hampering efforts to understand the molecular bases of phenotypic diversification in such a speciose clade. In particular, the ∼400 species of anole lizard represent an extensive squamate radiation. 

Spreading through the Americas, the anoles lizards, evolved like Darwin's finches, adapting to different islands and different habitats on the mainland resulting in more than 400 species. Colleagues at the Smithsonian Tropical Research Institute (STRI) and Arizona State University compared anole lizard genomes searching for genetic evidence for rapid evolution that may account for differences between bodies of animals living in different environments. 

They discovered that changes in genes involved in the diencephalon (consisting of the hypothalamus, thalamus, metathalamus, pineal glands, and epithalamus), for color vision, hormones and the colorful dewlap that males bob to attract females, may contribute to the formation of boundaries between species. Genes regulating limb development also evolved especially quickly. One obvious explanation for such a faster rate of evolution is the anole lizards' faster rate of reproduction. Anoles typically mate in their first year of life, while other reptiles take much longer to reach sexual maturity. They also breed with many other individuals so mutations that make it difficult for individuals to survive are eliminated fairly quickly.

Overall, it seems that molecular changes underlying behavioral adaptations known to reinforce species boundaries were a key component in the diversification of anole lizards.