Publication Date
1-2-2024
Journal
Nature Communications
DOI
10.1038/s41467-023-44352-2
PMID
38167733
PMCID
PMC10761872
PubMedCentral® Posted Date
1-2-2024
PubMedCentral® Full Text Version
Post-print
Published Open-Access
yes
Keywords
Animals, Songbirds, Gene Expression Regulation, Genome, Genomics, Genetic Speciation, Hybridization, Genetic, Reproductive Isolation
Abstract
Behavioral variation abounds in nature. This variation is important for adaptation and speciation, but its molecular basis remains elusive. Here, we use a hybrid zone between two subspecies of songbirds that differ in migration - an ecologically important and taxonomically widespread behavior---to gain insight into this topic. We measure gene expression in five brain regions. Differential expression between migratory states was dominated by circadian genes in all brain regions. The remaining patterns were largely brain-region specific. For example, expression differences between the subspecies that interact with migratory state likely help maintain reproductive isolation in this system and were documented in only three brain regions. Contrary to existing work on regulatory mechanisms underlying species-specific traits, two lines of evidence suggest that trans- (vs. cis) regulatory changes underlie these patterns - no evidence for allele-specific expression in hybrids and minimal associations between genomic differentiation and expression differences. Additional work with hybrids shows expression levels were often distinct (transgressive) from parental forms. Behavioral contrasts and functional enrichment analyses allowed us to connect these patterns to mitonuclear incompatibilities and compensatory responses to stress that could exacerbate selection on hybrids and contribute to speciation.