Widespread adaptive evolution during repeated evolutionary radiations in New World lupins

Area of Science:

• Evolutionary Biology
• Genomics
• Plant Sciences

Background:

• The drivers of rapid species diversification remain largely unknown.
• Distinguishing between adaptive and non-adaptive evolutionary processes is crucial.
• Explosive species radiations present a key evolutionary puzzle.

Purpose of the Study:

• To investigate the evolutionary mechanisms behind rapid species radiations in New World lupins (Lupinus, Leguminosae).
• To determine the relative roles of Darwinian adaptation versus non-adaptive processes in driving diversification.
• To examine the genomic basis of rapid evolutionary radiations.

Main Methods:

• Comparative genomic analysis of rapidly diversifying lupins and related species.
• Analysis of coding and regulatory genetic changes across plant genomes.
• Correlation of gene expression shifts with diversification rates and trait evolution.

Main Results:

• Rapid radiations in New World lupins were associated with increased adaptation frequency across coding and regulatory elements genome-wide.
• Slowly diversifying lupins and other plant genera showed significantly less frequent adaptation.
• Shifts in optimal gene expression patterns coincided with accelerated diversification and the evolution of perenniality.

Conclusions:

• Darwinian adaptation, acting on both coding and regulatory changes, is the primary driver of rapid species diversification in New World lupins.
• This study provides the first clear evidence for accelerated, lineage- and genome-wide Darwinian evolution during rapid diversification events.
• Findings reconcile debates on the importance of protein-coding versus regulatory evolution in driving evolutionary radiations.