The role of the environment on the genetic divergence between two Boa imperator lineages

Abstract

AbstractAimA fundamental problem in evolutionary biology has been understanding the role of environmental factors in the process of genetic diversification. Our main goal was to define the ecological niches of two Boa imperator lineages, in order to assess if environmental drivers could be associated with the divergence and genetic variation between them. We quantified the environmental niches at two evolutionary and geographical scales: regional‐historical (lineages) and local‐ecological (individuals within lineages).LocationNeotropical region of Mexico and mainland Central America.MethodsWe performed ecological niche modelling (ENM) methods by defining the accessibility area per B. imperator lineage, based on their geographic ranges, to analyse ecological and geographical distributions. We applied statistics of niche overlap, interpredictability, equivalency and similarity. We tested the niche‐centrality hypothesis within lineages by evaluating the relationship between genetic metrics and the distance to ecological and geographical centroids.ResultsTemperature seasonality, precipitation and elevation were the most informative environmental variables (GARP and MaxEnt). Ecological interprediction and niche similarity and equivalency tests revealed a dynamic process of niche evolution, where the niches of the two lineages are not identical but still showed a signature of niche conservatism. Correlation analyses between genetic variability and structure showed negative correlations with distance to ecological and geographical centroids at the local level.Main conclusionsOur results support the role of environmental variables as significant and highly accurate predictors of lineage distribution and divergence, in agreement with the boa's evolutionary history. The niches of the two lineages are not identical, sharing environmental niche space but not all ecological variables. A historically more recent signal of genetic structure within lineages was evident, where the quality of the ecological niche further influences genetic distribution patterns within populations. Our results illustrate how ENM may validate evolutionary patterns from a biogeographical and phylogeographical framework.