Phylotranscriptomic insights into Asteraceae diversity, polyploidy, and morphological innovation

Area of Science:

• Evolutionary Biology
• Plant Science
• Genomics

Background:

• Biodiversity distribution is uneven across related taxa, prompting research into contributing factors.
• The sunflower family (Asteraceae) is exceptionally diverse (>26,000 species), with concentrated diversity in specific subfamilies, making it an ideal model for studying biodiversity drivers.

Purpose of the Study:

• To investigate the evolutionary history and diversification patterns within the sunflower family (Asteraceae).
• To identify key factors, including climate shifts, whole-genome duplications (WGDs), and morphological evolution, that have shaped Asteraceae biodiversity.

Main Methods:

• Phylotranscriptomic analyses of 244 transcriptomes and genomes.
• Construction of a robust phylogeny for Asteraceae and its subfamilies/tribes.
• Detection of changes in diversification rates and identification of associated evolutionary events.

Main Results:

• A well-supported phylogeny confirmed the monophyly of Asteraceae and most of its subfamilies and tribes.
• The origin of Asteraceae was dated to approximately 83 million years ago, with major divergences predating the Cretaceous-Paleocene boundary.
• Forty-one whole-genome duplications (WGDs) were identified in Asteraceae, and shifts towards herbaceousness and capitulescence were linked to increased diversification rates.

Conclusions:

• Whole-genome duplications (WGDs) likely provided genetic novelty supporting early morphological transitions and adaptation in Asteraceae.
• Morphological innovations, such as herbaceousness and capitulescence, conferred a competitive advantage, driving niche adaptation and increasing biodiversity.
• The study provides a framework for understanding the complex interplay of factors driving exceptional biodiversity in the sunflower family.