Shifts in diversification rates linked to biogeographic movement into new areas, an example of disparate continental distributions and a recent radiation in the Andes [article]

Simon Uribe-Convers, David C Tank
2015 bioRxiv   pre-print
Premise of the study: Clade specific bursts in diversification are often associated with the evolution of key innovations. However, in groups with no obvious morphological innovations, observed upticks in diversification rates have also been attributed to the colonization of a new geographic environment. In this study, we explore the systematics, diversification dynamics, and historical biogeography of the plant clade Rhinantheae in the Orobanchaceae, with a special focus on the Andean clade of
more » ... the genus Bartsia L.. Methods: We sampled taxa from across Rhinantheae, including a representative sample of Andean Bartsia species. Using standard phylogenetic methods, we reconstructed evolutionary relationships, inferred divergence times among the clades of Rhinantheae, elucidated their biogeographic history, and investigated diversification dynamics. Key results: We confirmed that the South American Bartsia species form a highly supported monophyletic group. The median crown age of Rhinantheae was determined to be ca. 30 Ma, and Europe played an important role in the biogeographic history of the lineages. South America was first reconstructed in the biogeographic analyses around 9 Ma, and with a median age of 2.59 Ma, this clade shows a significant uptick in diversification. Conclusions: Increased net diversification of the South American clade corresponds with biogeographic movement into the New World. This happened at a time when the Andes were reaching the necessary elevation to host an alpine environment. Although a specific route could not be identified with certainty, we provide plausible hypotheses to how the group colonized the New World.
doi:10.1101/019554 fatcat:mzylfkid6jg3hebpxbaynmatji