Well-resolved phylogeny reveals multiple origins of keel flowers during the diversification of papilionoid legumes

Cai, L.; Cardoso, D.; Tressel, L. G.; Lee, C.; Shrestha, B.; Choi, I.-S.; Lima, H. C.; Queiroz, L. P.; Ruhlman, T. A.; Jansen, R. K.; Wojciechowski, M. F.

doi:10.1101/2024.10.07.617045

bioRxiv · 10.1101/2024.10.07.617045

Well-resolved phylogeny reveals multiple origins of keel flowers during the diversification of papilionoid legumes

Cai, L.·Cardoso, D.·Tressel, L. G.·Lee, C.·Shrestha, B.·Choi, I.-S.·Lima, H. C.·Queiroz, L. P.·Ruhlman, T. A.·Jansen, R. K.·Wojciechowski, M. F.

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Abstract

O_LIThe butterfly-shaped keel flower is a highly successful floral form in angiosperms. These flowers steer the mechanical interaction with bees and thus are hypothesized to accelerate pollinator-driven diversification. The exceptionally labile evolution of keel flowers in Papilionoideae (Fabaceae) provides a suitable system to test this hypothesis. C_LIO_LIUsing 1,456 low-copy nuclear loci, we confidently resolve the early divergence history of Papilionoideae. Constrained by this backbone phylogeny, we generated a time tree for 3,326 Fabales to evaluate the tempo and mode of diversification within a state-dependent evolutionary framework. C_LIO_LIThe first keel flowers emerged around 59.0 Ma in Papilionoideae, predating the earliest fossil by 3-4 million years. The Miocene diversification of Papilionoideae coincided with rapid evolution of keel flowers. At least six independent origins and thirty-two losses of keel flowers were identified in Papilionoideae, Cercidoideae, and Polygalaceae. However, the state-dependent diversification model was not favored. C_LIO_LILack of radiation associated with keel flowers suggests that diversification within Papilionoideae was not solely driven by pollinator-mediated selection, but instead an outcome of the synergistic effects of multiple innovations including nitrogen fixation and chemical defense as well as dispersal into subtropical and temperate regions. C_LI

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Cai, L., Cardoso, D., Tressel, L. G., Lee, C., Shrestha, B., Choi, I.-S., Lima, H. C., Queiroz, L. P., Ruhlman, T. A., Jansen, R. K., Wojciechowski, M. F.. 2024-10-11. Well-resolved phylogeny reveals multiple origins of keel flowers during the diversification of papilionoid legumes. https://doi.org/10.1101/2024.10.07.617045

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