Oral Paper

         Phylogenomics

Phylogenomic insights into the evolution, biogeography, and taxonomy of Andean Weinmannia (Cunoniaceae)

Presenting Author
Eduardo Aguirre Mazzi
Description
The Andes Mountains of South America are one of the most biodiverse regions on the planet and are home to many large plant radiations. One example of an important Andean plant radiation is Weinmannia section Weinmannia (Cunoniaceae), a clade of evergreen trees and shrubs that are prominent members of Andean forests. Most of the diversity in the group (> 90 Species) is distributed mainly in the Andean region, but some species are found in Atlantic forests, the Tepuis formations of the Guyana shield, the mountains of Central America and the Caribbean islands, and in temperate forests from Southern South America. Despite high levels of diversity found in Andean forests, the evolution of this group is poorly understood, and many species limits are unclear. The aim of this study was to elucidate the phylogenetic relationships among Andean Weinmannia species and to test the monophyly of morphologically described species. We estimated a maximum likelihood phylogeny of the genus based on 2b-RAD sequence data of Weinmannia species distributed across the Andes spanning Chile, Bolivia, Peru, Ecuador, and Colombia. Whenever it was possible, we included at least three individuals of each species and location, and we excluded all putative hybrids identified morphologically or through preliminary molecular data analysis (i.e., STRUCTURE). The results of the study showed that phylogenetic relationships exhibited a strong geographic structure, with species from Ecuador and Colombia forming distinct clades nested within a larger clade consisting of species from the southern Andes and Bolivia. Additionally, there was a clear pattern in which specimens collected from southern latitudes (Chile) grouped closer to the root of the phylogeny, whereas those from northern latitudes (Colombia and Ecuador) were placed closer to the crown of the tree. This phylogenetic pattern suggests that the lineage diversified as it dispersed from south to north, tracking cool environments that originated with the Andean uplift. In addition, we did not find all morphologically described species to be monophyletic; for example, specimens identified as W. pinnata and W. balbisiana were assigned to different clades along with several different species. In addition, clades often contained species with disparate morphologies, ranging from pinnate leaves to simple leaves. Altogether, these findings suggest either that these species may have experienced hybridization and introgression with relatives or that the genus has repeatedly evolved similar morphologies in different locations. Weinmannia promises to be an important model for understanding the ecology and evolution of plants that occupy a broad range of elevations in the Andes, and further research will continue to explore the main processes driving the diversification of the genus in the Andes from an integrative taxonomy perspective.