Genetic affinities within the Herring Gull Larus argentatus assemblage revealed by AFLP genotyping

To date, the taxonomic status of circumpolar breeding populations of the He rring Gull Larus argentatus, the Lesser Black-backed Gull Larus fuscus, and the closely related Yellow-legged Gull Larus cachinnans has been based on differences or similarities in phenotype, morphology, and feeding and prema ting behavior. To shed some new light on the many taxonomic uncertainties s urrounding these taxa, we describe the results of a large DNA study based o n comparing the distribution of 209 biallelic markers among 109 gulls, repr esenting 11 gull taxa of the Herring Gull assemblage and the Common Gull La rus canus. A detailed phylogenetic analysis failed to show clustering of in dividuals into groups representing either geographic origin or phenotype. A lternatively, birds were grouped into taxa defined on the basis of phenotyp e and geographic origin or phenotype alone. Genetic analyses revealed signi ficantly different genetic distances between all pairs of taxa. However, ba sed on these genetic distances, again no consistent phylogenetic tree could be constructed. Analysis of molecular variance indicated that about 77% of the total genetic variability among these gulls could be explained by with in-taxon differences. Only 23% of the total genetic variability was due to genetic differences between taxa, irrespective of their species or subspeci es status. Although this seems to challenge the current taxonomic treatment of the herring gull assemblage, our results are too premature and too inco mplete to recommend a drastic change.