Selection at behavioral, developmental and metabolic genes is associated with the northward expansion of a successful tropical colonizer

Abstract

23What makes a species able to colonize novel environments? This question is key to understand 24 the dynamics of adaptive radiations and ecological niche shifts, but the mechanisms that underlie 25 expansion into novel habitats remain poorly understood at a genomic scale. Lizards from the 26 genus Anolis are typically tropical and the green anole (Anolis carolinensis) constitutes an 27 exception since it expanded into temperate North America from subtropical Florida. Thus, we 28 used the green anole as a model to investigate signatures of selection associated with 29 colonization of a new environment, namely temperate North America. To this end, we analyzed 30 29 whole genome sequences, representing the entire genetic diversity of the species. We used a 31 combination of recent methods to quantify both positive and balancing selection in northern 32 populations, including FST outlier methods, machine learning and ancestral recombination 33graphs. We naively scanned for genes of interest and assessed the overlap between multiple tests.34 Strikingly, we identified many genes involved in behavior, suggesting that the recent successful 35 colonization of northern environments may have been linked to behavioral shifts as well as 36 physiological adaptation. These results were robust to recombination, gene length and clustering. 37