Genomic architecture and introgression shape a butterfly radiation

Area of Science:

• Evolutionary Biology
• Genomics
• Speciation Research

Background:

• Heliconius butterflies exhibit rapid adaptive radiation.
• Understanding speciation requires analyzing genome-wide gene flow.
• Distinguishing incomplete lineage sorting from introgression is crucial.

Purpose of the Study:

• To investigate speciation history and gene flow architecture in Heliconius butterflies.
• To identify genomic regions affected by introgression.
• To characterize novel genetic elements involved in adaptive radiation.

Main Methods:

• Utilized 20 de novo genome assemblies.
• Employed statistical tests to differentiate incomplete lineage sorting from introgression.
• Analyzed the distribution of introgressed loci in relation to recombination rates and gene density.

Main Results:

• Gene flow has obscured ancient phylogenetic relationships across large genomic regions.
• Introgressed loci are less common in low-recombination, gene-rich areas.
• A novel inversion trapping a color pattern locus was identified and likely transferred via introgression.

Conclusions:

• Introgression plays a significant role in the adaptive radiation of Heliconius.
• Selective processes, including the purging of incompatible alleles, shape introgressed regions.
• Convergent evolution of rearrangements like inversions can occur through introgression.