Free Access
Genet. Sel. Evol.
Volume 33, Number 5, September-October 2001
Page(s) 529 - 542
DOI: 10.1051/gse:2001131

Genet. Sel. Evol. 33 (2001) 529-542

Differentiation among Spanish sheep breeds using microsatellites

Juan-José Arranz, Yolanda Bayón and Fermín San Primitivo

Departamento de Producción Animal, Universidad de León, 24071 León, Spain

(Received 2 November 2000; accepted 23 April 2001)

Genetic variability at 18 microsatellites was analysed on the basis of individual genotypes in five Spanish breeds of sheep -Churra, Latxa, Castellana, Rasa-Aragonesa and Merino -, with Awassi also being studied as a reference breed. The degree of population subdivision calculated between Spanish breeds from $F_{\rm ST}$ diversity indices was around 7% of total variability. A high degree of reliability was obtained for individual-breed assignment from the 18 loci by using different approaches among which the Bayesian method provided to be the most efficient, with an accuracy for nine microsatellites of over 99% . Analysis of the Bayesian assignment criterion illustrated the divergence between any one breed and the others, which was highest for Awassi sheep, while no great differences were evident among the Spanish breeds. Relationships between individuals were analysed from the proportion of shared alleles. The resulting dendrogram showed a remarkable breed structure, with the highest level of clustering among members of the Spanish breeds in Latxa and the lowest in Merino sheep, the latter breed exhibiting a peculiar pattern of clustering, with animals grouped into several closely set nodes. Analysis of individual genotypes provided valuable information for understanding intra- and inter-population genetic differences and allowed for a discussion with previously reported results using populations as taxonomic units.

Key words: microsatellites / sheep breeds / population assignment / individual clustering analysis

Correspondence and reprints: Yolanda Bayón E-mail:

© INRA, EDP Sciences 2001