Genetic differentiation of an endangered capercaillie (Tetrao urogallus) population at the Southern edge of the species range

Abstract

The low-latitude limits of species ranges are thought to be particularly important as long-term stores of genetic diversity and hot spots for speciation. The Iberian Peninsula, one of the main glacial refugia in Europe, houses the southern distribution limits of a number of boreal species. The capercaillie is one such species with a range extending northwards to cover most of Europe from Iberia to Scandinavia and East to Siberia. The Cantabrian Range, in North Spain, constitutes the contemporary south-western distribution limit of the species. In contrast to all other populations, which live in pure or mixed coniferous forests, the Cantabrian population is unique in inhabiting pure deciduous forests. We have assessed the existence of genetic differentiation between this and other European populations using microsatellite and mitochondrial DNA (mtDNA) extracted from capercaillie feathers. Samples were collected between 2001 and 2004 across most of the current distribution of the Cantabrian population. Mitochondrial DNA analysis showed that the Cantabrian birds form a distinct clade with respect to all the other European populations analysed, including the Alps, Black Forest, Scandinavia and Russia, which are all members of a discrete clade. Microsatellite DNA from Cantabrian birds reveals the lowest genetic variation within the species in Europe. The existence of birds from both mtDNA clades in the Pyrenees and evidence from microsatellite frequencies for two different groups, points to the existence of a Pyrenean contact zone between European and Cantabrian type birds. The ecological and genetic differences of the Cantabrian capercaillies qualify them as an Evolutionarily Significant Unit and support the idea of the importance of the rear edge for speciation. Implications for capercaillie taxonomy and conservation are discussed.

Habitat partitioning in endangered Cantabrian capercaillie Tetrao urogallus cantabricus

“…Cantabrian capercaillie occupies a very southerly range within the grouse family (Quevedo et al 2006b), and has recently been identified as an Evolutionarily Significant Unit because of its unique ecological and genetic characteristics (Rodríguez-Muñoz et al 2007). The population appears to show low recruitment, with values as low as 0.54 juveniles per hen at the end of the summer and 74% of broodless hens in an 8-year period (Bañuelos et al this study, see ''Methods'' for details).…”

Diet and habitat selection in Cantabrian Capercaillie (Tetrao urogallus cantabricus): ecological differentiation of a rear-edge population

“…Hence, the population may be expected to show marked ecological and behavioral differentiation related to its distinct habitat. Although the population is known to be an evolutionary significant unit and may be part of a distinct southern capercaillie lineage (Duriez et al 2007; Rodríguez-Muñoz et al 2007), its potential ecological peculiarities remain largely unknown (e.g. Storch 2007).…”

Subspecies Cantabrian capercaillie Tetrao urogallus cantabricus endangered according to IUCN criteria

“…Recent phylogenetic studies indicate that the subspecies T. u. cantabricus (Castroviejo 1967(Castroviejo , 1975, an endemic of the Cantabrian Mountains of northwest Spain, forms a clade different from other European capercaillie (Rodríguez Muñ oz et al 2006), qualifies to be considered as an Evolutionarily Significant Unit (Moritz 1994(Moritz , 2002, and therefore deserves international conservation concern.…”