Genomic signatures of drift and selection driven by predation and human pressure in an insular lizard

Abstract

[EN]Genomic divergence was studied in 10 small insular populations of the endangered Balearic Islands lizard (Podarcis lilfordi) using double digest restriction-site associated DNA sequencing. The objectives were to establish levels of divergence among populations, investigate the impact of population size on genetic variability and to evaluate the role of diferent environmental factors on local adaptation. Analyses of 72,846 SNPs supported a highly diferentiated genetic structure, being the populations with the lowest population size (Porros, Foradada and Esclatasang islets) the most divergent, indicative of greater genetic drift. Outlier tests identifed ~2% of loci as candidates for selection. Genomic divergence-Enviroment Association analyses were performed using redundancy analyses based on SNPs putatively under selection, detecting predation and human pressure as the environmental variables with the greatest explanatory power. Geographical distributions of populations and environmental factors appear to be fundamental drivers of divergence. These results support the combined role of genetic drift and divergent selection in shaping the genetic structure of these endemic island lizard populations.

[ES] Se ha estudiado la divergencia genómica en 10 pequeñas poblaciones insulares de la lagartija balear (Podarcis lilfordi), en peligro de extinción, mediante la secuenciación del ADN asociada al sitio de restricción de doble digestión. Los objetivos eran establecer los niveles de divergencia entre las poblaciones, investigar el impacto del el tamaño de la población en la variabilidad genética y evaluar el papel de los diferentes factores ambientales en la adaptación local.