Gone With the Wind: Exploring a Vanished Rock Dove, <i>Columba livia</i>, Hybrid Zone in the Sahara Desert

Rock doves (<i>Columba livia</i>) are the wild ancestor of domestic and feral pigeons and had a wide distribution across Eurasia and the northern part of Africa. West African rock doves have been identified as genetically distinct from all other populations, possibly representing a distinct species. This divergence is hypothesized to have arisen through cycles of allopatry during the dry and wet Sahara periods. Based on the Refugia Theory and observed admixture patterns, it was proposed that a hybrid zone existed in the Sahara during its last green period, playing a critical role in the speciation of West African rock doves. This project aims to test the existence and location of this vanished hybrid zone by analyzing whole-genome sequences from six historical rock doves from previously unsampled populations in the Central Sahara and West Africa, along with published genomic data. By exploring population structure, genetic diversity, and admixture patterns, our results confirm the existence of the hybrid zone, likely located around the mountainous regions of northwest Africa. To explain the observed genetic differentiation of West African rock doves, we propose a four-step scenario involving speciation by reinforcement. Finally, we support a species-level taxonomic arrangement to designate the West African rock dove as <i>C. gymnocycla</i>.