BRIT Lunchtime Lecture: Evolutionary Dynamics of the Millettioid/Phaseoloid Clade (Fabaceae: Papilionoideae)

About the Research Lecture Series

The BRIT Research Lecture Series is designed to create community wide conversation about a diverse range of important and rapidly developing topics. This series gives scientists and speakers a forum for sharing the most current information about their areas of expertise and allows the public to interact with leading members of the local, national, and international scientific community.

This is a free hybrid seminar. Please join us in person in the Commons of the BRIT Building or virtually via the following link: https://us06web.zoom.us/j/86798152978.

Join us for a hybrid seminar presented by Dr. Oyetola Oyebanji, who recently joined our BRIT Research Team. We will explore how global dispersal, climate change, and ancient migration shaped one of the most diverse lineages in the legume family. Using DNA from over 760 species, this research reveals how the Millettioid/Phaseoloid clade evolved rapidly across continents over 60 million years—offering new insight into tropical biodiversity and plant evolution.

Unravelling the mechanisms driving the uneven temporal distribution of plant lineages is central to evolutionary biology. One of such lineages that the evolutionary trajectory is poorly understood is the Millettiod/Phaseoloid (MP) clade, a key lineage of the subfamily Papilionoideae (Fabaceae). To fill this gap, a robust time-calibrated phylogeny for 763 species (c. 80% of the genera) of the MP clade was generated leveraging Next Generation Sequence data. Phylogenetic analyses support the monophyly of the MP clade and four of its tribes (Abreae, Desmodieae, Indigofereae, and Psoraleeae), and two polyphyletic tribes (Millettieae and Phaseoleae). Timing between the origin (c. 62 Million years ago) and subsequent diversification (c. 61 Mya) are nearly simultaneous during the Paleocene in Cenozoic era. The MP clade originated in Africa (and most of its tribes) before radiating into Asia, Europe, Australia, and the Americas at different periods in the Cenozoic, supporting “out of the tropics hypothesis” and “tropical niche conservatism”, underscoring tropics as the evolutionary cradle and museum for this clade. Heterogenous diversification rates were supported by the possible evolutionary shifts detected across the phylogeny throughout the Cenozoic, with a spike in net diversification and speciation rates starting c. 10 Mya and continuing toward the present. Thus, the present-day species richness and spatio-temporal dynamics of the MP clade may stem from Paleocene-Eocene boreotropical migration, recurrent transcontinental long-distance dispersal via classic biogeographic mechanisms during the Cenozoic, and accelerated speciation post-Mid-Miocene Climatic Optimum (cooler climate). Together, these results illuminate diversification patterns of the MP clade, setting the stage for future evolutionary research on this important legume lineage.