Gene Regulatory Evolution During Speciation in a Songbird

Abstract

Over the last decade tremendous progress has been made towards a comparative understanding of gene regulatory evolution. However, we know little about how gene regulation evolves in birds, and how divergent genomes interact in their hybrids. Because of unique features of birds - female heterogamety, a highly conserved karyotype, and the slow evolution of reproductive incompatibilities - an understanding of regulatory evolution in birds is critical to a comprehensive understanding of regulatory evolution and its implications for speciation. Using a novel complement of analyses of replicated RNA-seq libraries, we demonstrate abundant divergence in gene expression between subspecies of zebra finches Taeniopygia guttata. By comparing parental populations and their F1 hybrids, we also show that gene misexpression is relatively rare, a pattern that may partially explain the slow buildup of postzygotic reproductive isolation observed in birds relative to other taxa. Although we expected that the action of genetic drift on the island-dwelling zebra finch subspecies would be manifested in a high rate of trans regulatory divergence, we found that most divergence was in cis regulation, following a pattern commonly observed in other taxa. Thus our study highlights both unique and shared features of avian regulatory evolution.