Selection and isolation define a heterogeneous divergence landscape between hybridizing Heliconius butterflies

Area of Science:

• Evolutionary Biology
• Genomics
• Speciation Research

Background:

• Hybridizing species offer insights into genomic variation and species boundary maintenance.
• Complex histories of isolation, gene flow, and selection create heterogeneous genomic divergence landscapes, complicating speciation history reconstruction.

Purpose of the Study:

• To reconstruct recent speciation in the erato clade of Heliconius butterflies by analyzing genomic divergence patterns.
• To investigate the genomic landscape of divergence across three contact zones of Heliconius erato and Heliconius himera.

Main Methods:

• Analysis of genomic divergence patterns in Heliconius butterflies.
• Application of demographic modeling to reconstruct gene flow, selection, and demographic changes.
• Utilizing the relationship between admixture and divergence with recombination rate variation.

Main Results:

• Heliconius erato and Heliconius himera exhibit intermediate genomic divergence, consistent with incomplete reproductive isolation.
• Periods of isolation and selection, followed by secondary contact with asymmetrical gene flow, are identified as key factors shaping genomic landscapes.
• Demographic modeling and recombination rate estimates effectively disentangle gene flow and selection contributions to genomic divergence.

Conclusions:

• The study successfully reconstructs recent speciation in the erato clade of Heliconius butterflies.
• Heterogeneous genomic landscapes are shaped by a combination of isolation, selection, and asymmetrical secondary gene flow.
• Demographic modeling is a powerful tool for understanding the interplay of evolutionary forces in speciation.