Interplay between conservatism and divergence in climatic niche evolution of Brassicaceae tribe Eudemeae shaped their distribution across the different environments of the Andes

Abstract

The Andean region is one of the most biodiverse areas, displaying high levels of endemism and spatial turnover of species. Tribe Eudemeae includes nine genera and 40 species distributed from the northern Andes in Colombia to the southernmost portion of the Andes in Argentina and Chile. Here, we generated a species-level phylogenetic tree to study their climatic niche evolution. We first analysed phylogenetic structure and evolutionary shifts among the main climatic spaces using model-based estimates. Second, we estimated climatic niches for each species and compared them in a phylogenetic context. In Eudemeae, three main groups of climatic spaces were found, mainly related to the northern and central Andes, the north-central portion of the southern Andes and the central-southern portion of the southern Andes. Results suggest that initial colonization of new climatic spaces in the evolution of the tribe appears to be promoted through shifts in adaptive regimes, whereas subsequent diversification of genera occurred predominantly under the same climatic regimes. This trade-off between niche conservatism and divergence appears to have modulated their diversification across the Andes and contributed to their current geographical distribution.