Ecomorphological evolution in the Liolaemus darwinii species group (Squamata: Liolaemini): adaptive diversification to climatic niches

CAMARGO, A.; SITES, J.W., JR.; MORANDO, M.; AVILA, L.J.

Raleigh

Congreso; Evolution 2014; 2014

American Society of Naturalist, Society for the Study of Evolution, Society of Systematic Biology

Patterns of diversification at the macroevolutionary level can be due to adaptation processes or simple random divergence. In turn, adaptive divergence can be driven by natural selection in response to ecological factors. In this work, we evaluated diversification models in the L. darwinii species group using comparative phylogenetic methods. We took seven morphometric measurements in males of 18 species and we obtained climatic data from georeferenced localities. First, we compared the fit of Brownian vs. adaptive models of diversification based on the morphological variation among species and a phylogeny for the group using the R packages ?picante? and ?geiger?. Second, we evaluated the evolutionary correlation between the morphological variation and the climatic niches using a phylogenetic canonical correlation analysis with the R package ?phytools?. Third, we fitted Ornstein-Uhlenbeck (OU) models of adaptive evolution to randomly evolving predictor (climatic) variables using the R script ?slouch?. Three morphometric traits showed phylogenetic signal and fitted a model of adaptive optima better than a Brownian model. Taking into account phylogeny, the morphological variation among species is highly and significantly correlated with the variation in climatic niches. OU models show that phylogenetic signal of several morphometic traits is the result of adaptive change to climatic variation instead of phylogenetic inertia. These results suggest that adaptive diversification in the L. darwinii group took place as a response to divergent climatic niches in the wide, latitudinal and altitudinal gradients of the Monte Desert in west-central Argentina.