No genetic differentiation, but less diversity, in the Iberian breeding population of the Eurasian Curlew (Numenius arquata)

Abstract

The Iberian Peninsula harbours an “Endangered” population of the Eurasian Curlew (Numenius arquata), of less than five breeding pairs, restricted to a small geographical area, the Terra Cha district in Lugo (Galicia, Spain). These birds constitute the southernmost breeding nuclei of the species, located 550 km southwest from the nearest nesting sites in France. The present study aims to shed light on the genetic pattern of this population, and quantify the current levels of genetic diversity. We sequenced one mitochondrial gene and two nuclear introns of Eurasian Curlew sampled during the breeding season in Spain, Germany, Sweden and the Russian Federation. Overall, we observed low genetic variation among loci, including a monomorphic intron. Neither mitochondrial DNA (mtDNA) nor nuclear DNA (nDNA) showed differentiation between the Iberian population and the European Curlew (Numenius arquata arquata). The Iberian birds share a single mtDNA haplotype, which is the most common among populations, and the four nDNA haplotypes present in the Iberian birds are shared with other populations, including that of the farmost Siberian Curlew (Numenius arquata orientalis). We could not reject the hypothesis of a recent colonization of the Iberian Peninsula by the European Curlew, but the lack of variation in the Iberian gene pool during the last decade suggests no current recruitment from other populations, which might impair the persistence of this peripheral breeding nucleus.