Environmental Variation Influences Genome Evolution in Hispaniolan Trunk Anoles (Anolis distichus)

Environmental variation often drives evolutionary processes like population differentiation, local adaptation and speciation. We used genome-scale data to investigate the contribution of environmental variation to evolution of the North Caribbean bark anole (Anolis distichus), a widespread common lizard that exhibits impressive phenotypic variation across varying habitats on the island of Hispaniola. We obtained new double-digest restriction-associated DNA sequence data (ddRADseq) from nearly 200 individuals and used 53 GIS data layers representing a range of environmental variables. We first asked how environmental variation has contributed to genome-wide differentiation across Hispaniola. We found that Hispaniola's three major mountain ranges contribute to deep genome-wide divergence and patterns of migration, that some deeply genomically divergent populations occupy significantly different environments, and that environmental variation is broadly capable of explaining more range-wide genomic differentiation than geographic distance alone. We then asked whether specific loci exhibit evidence of local adaptation to environmental variation using genotype-environment association (GEA) methods. We initially identified hundreds of loci broadly distributed across the genome that are significantly correlated with one or more environmental variables, but ultimately found that fewer than 100 of these candidate loci are shared across different GEA methods applied to our entire dataset, and that only 10 candidate loci are shared by independent analyses of two regional subsets of our dataset, suggesting parallel evolution is infrequent. Our study shows that abiotic environmental variation has played a critical role in explaining the evolution and diversity of a widespread and phenotypically diverse Caribbean anole species. La variaci & oacute;n ambiental a menudo impulsa procesos evolutivos como la diferenciaci & oacute;n entre poblaciones, adaptaci & oacute;n local y especiaci & oacute;n. Utilizamos datos a escala gen & oacute;mica para investigar la contribuci & oacute;n de la variaci & oacute;n ambiental a la evoluci & oacute;n de la lagartija de corteza (Anolis distichus), un lagarto com & uacute;n y muy extendido que exhibe una gran variaci & oacute;n fenot & iacute;pica en toda la isla de La Espa & ntilde;ola. Obtuvimos nuevos datos de secuencia de ADN asociado a sitios de restricci & oacute;n con doble digesti & oacute;n (ddRADseq) a partir de casi 200 individuos. Como variables ambientales utilizamos 53 capas de datos de tipo SIG que entre todas incluyen una amplia gama de variables. Con estos datos nos preguntamos en primer lugar c & oacute;mo la variaci & oacute;n ambiental ha contribuido a la diferenciaci & oacute;n de todo el genoma en La Espa & ntilde;ola. Encontramos que las barreras ambientales m & aacute;s obvias en La Espa & ntilde;ola (las tres cadenas monta & ntilde;osas principales) contribuyen a una profunda divergencia en todo el genoma e influyen en patrones de migraci & oacute;n donde algunas poblaciones gen & oacute;micamente divergentes ocupan ambientes significativamente diferentes y que la variaci & oacute;n ambiental en general explica m & aacute;s diferenciaci & oacute;n gen & oacute;mica en todo el rango de distribuci & oacute;n que la distancia geogr & aacute;fica sola. Luego, utilizando m & eacute;todos de asociaci & oacute;n genotipo-ambiente (GEA), nos preguntamos si loci o regiones espec & iacute;ficas del genoma exhiben evidencia de adaptaci & oacute;n local como resultado de la variaci & oacute;n ambiental. Inicialmente identificamos cientos de loci distribuidos a lo largo de todo el genoma que est & aacute;n significativamente correlacionados con una o m & aacute;s variables ambientales, pero finalmente descubrimos que menos de 100 de estos loci candidatos coinciden usando diferentes m & eacute;todos de GEA aplicados a todo el conjunto de datos, y que solo 10 loci candidatos coinciden si dividimos el conjunto de datos en dos regiones geogr & aacute;ficas y las analizamos independientemente. Nuestro estudio demuestra que la variaci & oacute;n ambiental abi & oacute;tica ha jugado un papel cr & iacute;tico en la evoluci & oacute;n y diversidad de una especie de lagarto anolino caribe & ntilde;o ampliamente distribuida y fenot & iacute;picamente diversa.