LAUSR

Biodiversity is not evenly distributed among related groups, raising questions about the factors contributing to such disparities. The sunflower family (Asteraceae, >26,000 species) is among the largest and most diverse plant families, but its species diversity is concentrated in a few subfamilies, providing an opportunity to study the factors affecting biodiversity. Phylotranscriptomic analyses here of 244 transcriptomes and genomes produced a phylogeny with strong support for the monophyly of the Asteraceae and the monophyly of most subfamilies and tribes. This phylogeny provides a reference for detecting changes in diversification rates and possible factors affecting Asteraceae diversity, which include global climate shifts, whole-genome duplications (WGDs), and morphological evolution. The origin of the Asteraceae was estimated at ~83 MYA, with most subfamilies having diverged before the Cretaceous-Paleocene boundary. Phylotranscriptomic analyses supported the existence of 41 WGDs in the Asteraceae. Changes to herbaceousness and capitulescence with multiple flower-like capitula, often with distinct florets and scaly pappus/receptacular bracts, are associated with multiple upshifts in diversification rate. WGDs might have contributed to the survival of the early Asteraceae by providing new genetic materials to support morphological transitions. The resulting competitive advantage for adapting to different niches would have increased biodiversity in Asteraceae. This article is protected by copyright. All rights reserved.