Genome-wide cline analysis identifies new barrier locus in Antirrhinum snapdragon hybrid zone

David L. Field and colleagues, writing in PLOS Genetics, report the identification of a new genomic region contributing to reproductive isolation between two subspecies of the snapdragon Antirrhinum majus. The study used genome-wide cline analysis — scanning for genomic regions where allele frequencies shift more steeply across a hybrid zone than the genome-wide average — as an alternative to the more commonly used FST-based differentiation scans.

The team included researchers from institutions including the John Innes Centre, the Institute of Science and Technology Austria, and the Chinese Academy of Sciences, among others. By applying the cline approach to a natural hybrid zone in the Pyrenees, they identified a locus not previously implicated in reproductive isolation in this system. The work adds to understanding of the genomic architecture of speciation and the maintenance of species boundaries in the face of gene flow.

The Antirrhinum hybrid zone is a long-established model system in evolutionary genetics, and the new locus was identified using phased whole-genome sequencing data. The authors note that cline analysis offers a potentially more robust signal of barrier loci than FST outlier approaches in cases where demographic history can confound differentiation statistics.

The paper is peer-reviewed and published in PLOS Genetics. It is of primary interest to evolutionary geneticists, population geneticists, and educators using Antirrhinum as a teaching model for speciation.