Factores geográficos y climáticos detrás de la diversificación de Citharexylum L.

FROST, LAURA; O'LEARY, NATALY; OLMSTEAD, RICHARD

Entre Ríos, Paraná

Jornada; XXXVIII Jornadas Argentina de Botánica; 2021

SAB

As a family of Neotropical origin that has remained largely constrained to tropical latitudes in the Americas, Verbenaceae are a good system with which to understand Neotropical diversification. Citharexylum, comprising 60-75 spp., is widespread geographically, occurring from northern Mexico to southern Brazil and Argentina, and climatically, occupying lowland moist forests, mid-elevation cloud forests, seasonally dry forests, high elevation shrublands, and xeric shrublands. Its distribution in multiple biomes across two continents provides an opportunity to understand the relative contributions of niche conservatism?radiation within a biome, possibly facilitated by dispersal between climatically similar but geographically distant regions?and niche evolution?adaptation to a different biome?to diversification. The evolutionary history of Citharexylum uncovers different modes of diversification in Neotropical regions. We find that dispersal between Mesoamerica and South America has been infrequent; instead, two major radiations have occurred in situ. In Mesoamerica, niche evolution has occurred more frequently and more recently, whereas in South America, niche evolution occurred deep in the evolutionary history of the lineage and daughter clades have since radiated within their ancestral biome. Despite these differences in diversification dynamics, we observe similar diversification rates in the two radiations and similar taxonomic diversity.