A DNA Replication Mechanism Can Explain Structural Variation at the Pigeon Recessive Red Locus

For species to adapt to their environment, evolution must act upon genetic variation that is present in the population. Elucidating the molecular mechanisms that give rise to this variation is thus of crucial importance for understanding how organisms evolve. In addition to variation caused by point mutations, structural variation (deletions, duplications, inversions, translocations) is also an important source of variety. Mechanisms involving recombination, transposition and retrotransposition, and replication have been proposed for generating structural variation, and each are capable of explaining certain rearrangements. In this study, we conduct a detailed analysis of two partially overlapping rearrangements (e(1) and e(2) allele) in domestic rock pigeon (Columba livia) which are both associated with the recessive red phenotype. We find that a replicative mechanism is best able to explain the complex architecture of the e(1) allele, and is also compatible with the simpler architecture of the e(2) allele as well.