Genetic variation at microsatellite loci in Spanish sheep

Genetic variation at 18 microsatellite loci was analysed in six indigenous Spanish sheep: Churra; Latxa; Manchega; Rasa-Aragonesa; Castellana and Merino. Merinos had frequently the highest number of alleles per locus, whereas Latxas showed the lowest one at many loci. Markers ordered decreasingly according to the number of variants differentiated in the whole population were: MAF70; TGLA13; CSSM66; BM143, BM6444; MAF36; MAF64; CSSM6; TGLA53; OarFCB11; MAF33; BM4621; MAF48; MAF65; BM1258; ILSTS002; ADCYC and OarCP34. Parameters of variability such as effective number of alleles and gene diversities corroborated the high level of variation frequently displayed by microsatellite markers. Comparison of allele distributions among populations and loci did not reveal consistent shapes. Distributions were centralised in some cases, whereas in others some kind of skewness was evident. Breed-specific alleles were detected at most loci, being frequent in Merinos and rare in Churras.