RT Journal Article SR Electronic T1 Diversification, disparification, and hybridization in the desert shrubs Encelia JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.31.230938 DO 10.1101/2020.07.31.230938 A1 Sonal Singhal A1 Adam B. Roddy A1 Christopher DiVittorio A1 Ary Sanchez-Amaya A1 Claudia L. Henriquez A1 Craig R. Brodersen A1 Shannon Fehlberg A1 Felipe Zapata YR 2020 UL http://biorxiv.org/content/early/2020/07/31/2020.07.31.230938.abstract AB There are multiple hypotheses for the spectacular plant diversity found in deserts. We explore how different factors, including the roles of ecological opportunity and selection, promote diversification and disparification in Encelia, a lineage of woody plants in the deserts of the Americas.Using a nearly complete species-level phylogeny along with a broad set of phenotypic traits, we estimate divergence times and diversification rates, identify instances of hybridization, quantify trait disparity, and assess phenotypic divergence across environmental gradients.We show that Encelia originated and diversified recently (mid-Pleistocene) and rapidly, with rates comparable to notable adaptive radiations in plants. Encelia probably originated in the hot deserts of North America, with subsequent diversification across steep environmental gradients. We uncover multiple instances of gene flow between species. The radiation of Encelia is characterized by fast rates of phenotypic evolution, trait lability, and extreme disparity across environments and between species-pairs with overlapping geographic ranges.Encelia exemplifies how interspecific gene flow in combination with high trait lability can enable exceptionally fast diversification and disparification across steep environmental gradients.Competing Interest StatementThe authors have declared no competing interest.