Format: ORAL

Livio Btscher1, Colin E. Hughes2, Jurriaan M. de Vos1

1 Department of Environmental Sciences, University of Basel, Basel, CH 2 Department of Systematic and Evolutionary Botany, University of Zürich, Zürich, CH

We present an overview of why the genus Lupinus L. (Fabaceae) has emerged as a model clade for studying rapid recent plant radiations providing potent insights into the drives rapid ecological and phenotypic plant diversification. The Western New World Lupinus clade with more than 200 species, comprises a series of nested and parallel radiations, including the recent rapid Andean radiation. Previous work has shown that a combination of biome shifts and life form changes underpin accelerated species diversification, but detailed understanding of the interactions between environmental and phenotypic evolution is lacking. Moreover, while multiple drivers of high rates of species diversification have been proposed, the drivers of rapid ecological and morphological trait evolution remain unclear. Here we leverage taxonomic, morphological, biogeographic, and environmental data to ask what environmental factors drove the apparently differential rates of trait evolution among western New World Lupinus lineages. Specifically, we test which model classes, including models of incremental or pulsed change (i.e., Lvy processes), best describe evolution across eight traits, and whether life forms, climatic niches, and biographic realms affect the tempo and mode of trait evolution. We demonstrate a radically expanded trait space occupancy by the Andean clade. We reveal support for pulsed evolution in three of eight plant traits and identify five nested branches in the Andean clade that are congruent with evolutionary jumps, rather than a single shift to an overall higher rate of incremental evolution. We find that these shifts are associated with perennials occupying aseasonal temperature niches, but not all such lineages experience jumps, suggesting that longer life spans and longer growing seasons are prerequisites but, alone are insufficient to drive episodes of pulsed trait evolution. Our findings demonstrate the existence of rapid bursts of trait evolution and suggest that pulsed evolution may be a common feature of plant radiations.