Repeated long-distance dispersal and convergent evolution in hazel

Area of Science:

• Botany
• Evolutionary Biology
• Biogeography

Background:

• The genus Corylus (hazel) comprises economically important temperate tree and shrub species with a worldwide distribution.
• Closely related species offer insights into global evolutionary and biogeographic processes.

Purpose of the Study:

• To construct a time-calibrated phylogenetic tree for the genus Corylus.
• To model the biogeographic history and evolutionary pathways of tree and shrub forms within Corylus.

Main Methods:

• Utilized multiple nuclear and chloroplast DNA loci for phylogenetic analysis.
• Employed phylogenetic methods to reconstruct the genus's evolutionary and biogeographic history.

Main Results:

• Estimated multiple long-distance dispersal events of Corylus lineages between Europe and Asia, and from Asia to North America.
• Identified 4-5 independent instances of convergent evolution driving the tree versus shrub form diversification over the past 25 million years.
• Observed significant discordance between nuclear and chloroplast phylogenies, suggesting potential chloroplast capture and past introgression.

Conclusions:

• The study presents a novel phylogenetic hypothesis for Corylus.
• Long-distance dispersal is a key factor in shaping the global distribution of temperate plant biodiversity.
• Convergent evolution has played a significant role in the diversification of growth forms within the genus.