Premium
Patterns of divergence across the geographic and genomic landscape of a butterfly hybrid zone associated with a climatic gradient
Author(s) -
Ryan Sean F.,
Fontaine Michael C.,
Scriber J. Mark,
Pfrender Michael E.,
O'Neil Shawn T.,
Hellmann Jessica J.
Publication year - 2017
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.14236
Subject(s) - biology , reproductive isolation , cline (biology) , evolutionary biology , context (archaeology) , hybrid zone , local adaptation , genetic divergence , ecological speciation , adaptation (eye) , ecological genetics , ecology , genetics , genetic variation , gene , gene flow , genetic diversity , population , paleontology , demography , neuroscience , sociology
Hybrid zones are a valuable tool for studying the process of speciation and for identifying the genomic regions undergoing divergence and the ecological (extrinsic) and nonecological (intrinsic) factors involved. Here, we explored the genomic and geographic landscape of divergence in a hybrid zone between Papilio glaucus and Papilio canadensis . Using a genome scan of 28,417 dd RAD SNP s, we identified genomic regions under possible selection and examined their distribution in the context of previously identified candidate genes for ecological adaptations. We showed that differentiation was genomewide, including multiple candidate genes for ecological adaptations, particularly those involved in seasonal adaptation and host plant detoxification. The Z chromosome and four autosomes showed a disproportionate amount of differentiation, suggesting genes on these chromosomes play a potential role in reproductive isolation. Cline analyses of significantly differentiated genomic SNP s, and of species‐diagnostic genetic markers, showed a high degree of geographic coincidence (81%) and concordance (80%) and were associated with the geographic distribution of a climate‐mediated developmental threshold (length of the growing season). A relatively large proportion (1.3%) of the outliers for divergent selection were not associated with candidate genes for ecological adaptations and may reflect the presence of previously unrecognized intrinsic barriers between these species. These results suggest that exogenous (climate‐mediated) and endogenous (unknown) clines may have become coupled and act together to reinforce reproductive isolation. This approach of assessing divergence across both the genomic and geographic landscape can provide insight about the interplay between the genetic architecture of reproductive isolation and endogenous and exogenous selection.