Native breeds demonstrate high contributions to the molecular variation in northern European sheep

Abstract

Population contribution to genetic diversity can be estimated using neutral variation. However, population expansion or hybridization of diverged ancestries may weaken correlation between neutral and non-neutral variation. Microsatellite variation was studied at 25 loci in 20 native and 12 modern or imported northern European sheep breeds. Breed contributions to total gene diversity, allelic richness and mean allele-sharing distance between individuals were measured. Indications of changes in population size and admixtures of divergent ancestries were investigated and the extent of inbreeding was estimated. The northern European sheep demonstrated signs of reduction in effective population size. Many old, small populations made a substantial positive contribution to total molecular variation, but populations with several divergent major ancestries did not contribute substantially to molecular variation, with the exception of the Norwegian Rygja sheep. However, several diverged major ancestries may cause it to contribute less to non-neutral variation than expected from the microsatellite data. Breed uniqueness and within-breed variability generally had opposite effects on breed contributions to molecular diversity. The degree of inbreeding did not reflect the breed contribution to total gene diversity or allelic richness, but inbred populations increased the mean allele-sharing distance between individuals. Our study indicates breed conservation to be especially important in maintaining allelic variation in northern European sheep and supports the evolutionary importance of peripheral populations.

Study of genetic differences among Slovak Tsigai populations using microsatellite markers

“…Tapio et al (2005) found similar allelic richness studying European sheep (2.62-6.26). In Romanian Tsigai 7.52 alleles per breed were detected (Peter et al, 2007).…”

Genetic differentiation between the Old and New types ofSerbianTsigaisheep

“…A set of 15 microsatellites available for all breeds (refer to [25]) was used for the calculation. The analysis was done using DISPAN [12].…”

“…Two sheep breeds from Ukraine (Carpathian Mountain and Sokolsk), two from Russia (Russian Tsigai and Romanov) and one from Finland (Finnsheep), described by Tapio et al [25,26], were included in the analysis of breed relationships.…”

“…In total 100 Serbian Tsigai sheep were genotyped for 23 Samples from Nordic standard animals were included in all gel-runs allowing adjustment of all allele sizes to the agreed sizes of the North-SheD reference samples ( [25], NorthSheD project www.lbhi.is/northshed).…”

North European short-tailed breeds of sheep: a review

“…Although information was obtained on 34 shorttailed breeds originating in Northern Europe, it should be kept in mind that several of them are now rare and endangered and continued efforts are needed to conserve their great genetic diversity (Tapio, 2006). Breeds with North European short-tail ancestry such as the Estonian Ruhnu, the Estonian Saaremaa, the Lithuanian Native Coarsewooled and the Norwegian Grey Troender sheep (Tapio et al, 2005a and2005b;Zapasnikiene and Nainiene, 2008), and possibly the -E-mail: ord@bondi.is Herdwick sheep in the United Kingdom (Ryder, 1983), are not classified as short-tails, presumably due to their longer tails as a results of crossing with long-tailed breeds. Thus, they could not be included in the survey.…”