Genetic structure and differentiation of the endemic Bolle's Laurel Pigeon (Columba bollii) in the Canary Islands

Island archipelagos are global biodiversity hotspots since they often foster high concentrations of diverse lineages and endemic species. Here, we examine the population genetics of the endemic Bolles Laurel Pigeon Columba bollii, a frugivorous bird inhabiting subtropical laurel forests. We genotyped ten microsatellite loci using DNA obtained from moulted tail feathers collected at eight sampling sites on the four western islands of the Canarian archipelago. Analyses including F-statistics, Bayesian clustering approaches, isolation by distance tests and population graph topologies, were used to infer the genetic diversity and the population differentiation within and among insular populations. Additionally, we evaluated the effect of null alleles on data analysis. Low genetic diversity was found in all populations of Bolles Laurel Pigeon, with no significant differences in diversity among them. However, significant genetic differentiation was detected among all populations, with pigeons from La Palma and El Hierro exhibiting the closest affinity. Bayesian clustering supported population separation between islands, and also detected fine-scale structure within the Tenerife and La Gomera populations. Present-day pigeon movements appear to occur between islands, however, this has not been sufficient to remove the signature of genetic divergence among the populations of Bolles Laurel Pigeon, which was moderately linked to geographical distance. According to metapopulation structure, this study suggests that the evolutionary history of C. bollii is closely related to the geological past of these oceanic islands and the distribution range of its habitat, the laurel forest. Finally, conservation implications for the species are discussed.