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Abstract— Antennaria are dioecious perennial herbs distributed mainly in the Holarctic Region, with their major center of diversity in the Rocky Mountains of Western North America. The genus comprises 33 known sexual diploid/tetraploid species and at least five polyploid agamic complexes which mostly reproduce by forming asexual seeds. We performed a phylogenetic reconstruction of the 31 sexually-reproducing Antennaria species using a novel target enrichment method that employs custom capture probes designed to work across Asteraceae. Both concatenated and coalescent-based analyses of DNA sequence data from hundreds of nuclear loci recovered Antennaria as a monophyletic group except for the long-disputed species, Antennaria linearifolia , which was recovered outside of the genus. Antennaria was further resolved into three distinct, major lineages. Analysis of ancestral state reconstruction of 12 taxonomically important morphological characters elucidated patterns of character evolution throughout the genus. Estimations of ancestral geographic ranges and molecular dating analyses demonstrated the Rocky Mountain region, including the Vancouverian Province, as the center of origin for the genus Antennaria, around 5.8 MYA. Subsequent dispersals of Antennaria into the Arctic and Appalachian provinces, Canadian provinces, and Eurasia took place roughly 3.2 MYA, 2.4 MYA, and 1.6 MYA, respectively. Biogeographical stochastic mapping indicated that 51.4% of biogeographical events were based on within-area speciation. The remaining 48.6% of the events were divided into two types of dispersals: 1) range expansion dispersals (anagenic, 37%), and 2) founder/jump dispersals (cladogenic, 11.6%). Our results provide a framework for future evolutionary studies of Antennaria, including speciation, origin(s) of polyploidy, and agamospermy in the genus. 

The sunflower family, Asteraceae, comprises 10% of all flowering plant species and displays an incredible diversity of form. Asteraceae are clearly monophyletic, yet resolving phylogenetic relationships within the family has proven difficult, hindering our ability to understand its origin and diversification. Recent molecular clock dating has suggested a Cretaceous origin, but the lack of deep sampling of many genes and representative taxa from across the family has impeded the resolution of migration routes and diversifications that led to its global distribution and tremendous diversity. Here we use genomic data from 256 terminals to estimate evolutionary relationships, timing of diversification(s), and biogeographic patterns. Our study places the origin of Asteraceae at ∼83 MYA in the late Cretaceous and reveals that the family underwent a series of explosive radiations during the Eocene which were accompanied by accelerations in diversification rates. The lineages that gave rise to nearly 95% of extant species originated and began diversifying during the middle Eocene, coincident with the ensuing marked cooling during this period. Phylogenetic and biogeographic analyses support a South American origin of the family with subsequent dispersals into North America and then to Asia and Africa, later followed by multiple worldwide dispersals in many directions. The rapid mid-Eocene diversification is aligned with the biogeographic range shift to Africa where many of the modern-day tribes appear to have originated. Our robust phylogeny provides a framework for future studies aimed at understanding the role of the macroevolutionary patterns and processes that generated the enormous species diversity of Asteraceae.