Se avecinan cambios taxonómicos

BirdLife acaba de hacer pública la nueva lista 2009-2010 de cambios taxonómicos recomendados. En lo que atañe a gaviotas, las novedades son sorprendentes. Más abajo pego el texto, con indicación del link donde se puede descargar la lista Excel completa (haz click aquí). 

Resumiendo, merece una mención especial la incoporación de los taxones:
  

L.armenicus a L. michahellis

L. vegae/smithsonianus/mongolicus a L. argentatus 

L.  taymirensis/barabensis a L. fuscus

Parece que la falta de estudios genéticos definitivos es esencial, y la sola diferenciación morfológica no puede darse por concluyente.

Un nuevo giro de tuerca en la taxonomía de un grupo de aves tan complicado como son las gaviotas. En mi opinión, estas conclusiones son muy conservadoras, dado que existen notables diferencias (y estudios genéticos serios, en muchos casos) en algunos de los taxones que perderían su condición de especie (por ejemplo, L. armenicus)

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Larus cachinnans (Sibley and Monroe 1990, 1993) has been split into L. cachinnans and L. michahellis; L. armenicus (Sibley and Monroe 1990, 1993; AERC TAC) has been lumped into L. michahellis. 

These changes to the BirdLife checklist follow examination by the BirdLife Taxonomic Working Group (BTWG) of a recent review of large white-headed gulls in the Holarctic by Collinson et al. (2008) and associated literature referred to therein. 

The following species level treatment, shown with subspecific placements, has been adopted by the BTWG: L. fuscus (with intermedius, graellsii, heuglini, taimyrensis and barabensis); L. argentatus (with argenteus, smithsonianus, vegae and mongolicus); L. michahellis (with atlantis and armenicus) and L. cachinnans. This treatment is based on evidence of sympatry, and morphological and behavioural differences, but rejects further splits derived from phylogentic analyses based on mtDNA because Collinson et al. (2008) admit that (1) mtDNA lineages can disappear by random events, resulting in misplacements and displacements in phylogenies, and (2) hybridisation, which seems very widespread in these white-headed gulls, can result in "adoption" of mtDNA sequences by another taxon, completely obscuring the real situation. Collinson et al. (2008) explicitly state "these complications do not just make gull phylogenies difficult: they may cause entirely false conclusions to be drawn about species boundaries… it must be recognised that splits or lumps based solely on mtDNA cannot be regarded as robust". While proposed splits not adopted here are not based solely on mtDNA, the morphological evidence presented is not conclusive, taxa are only diagnosable in some cases and there is hybridisation between them.