Genetic variation and population structure of Italian native sheep breeds undergoing in situ conservation

• Published in: Journal of animal science 2009-12, Vol.87 (12), p.3837-3844
• Main Authors: Dalvit, C, De Marchi, M, Zanetti, E, Cassandro, M
• Format: Article
• Language: English
• Subjects: Alleles; Alpagota (sheep breed); animal genetic resources; animal genetics; Animal Husbandry; Animal productions; Animals; Bergamasca (sheep breed); Biological and medical sciences; breed differences; Breeding; Brogna (sheep breed); conservation programs; founder effect; Foza (sheep breed); Fundamental and applied biological sciences. Psychology; gene frequency; genetic distance; Genetic Drift; genetic variation; Genetic Variation - genetics; Genetics, Population; heterozygosity; Heterozygote; Inbreeding; Italy; Lamon (sheep breed); microsatellite repeats; Microsatellite Repeats - genetics; molecular sequence data; population genetics; rare breeds; sheep; Sheep - genetics; sheep breeds; surveys; Terrestrial animal productions; Vertebrates
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jas.2008-1682

The genetic variability and presence of population substructures in 4 native Northern Italian sheep breeds, Alpagota, Brogna, Foza, and Lamon, undergoing in situ conservation, and 1 widespread Italian breed, Bergamasca, were studied by investigating 19 microsatellite markers. The breeds showed considerable genetic variability in terms of number of alleles and heterozygosity, with the exception of Alpagota, which was the least variable (0.607). Nevertheless, a significant deficit of heterozygotes was observed in each breed due to rather increased levels of inbreeding or to the presence of population substructures, probably caused by increased genetic variation in the founder populations. The analyses evidenced clear genetic differentiation (FST = 0.085), reduced levels of admixture, and presence of private alleles among the breeds, confirming their genetic uniqueness. In particular, according to Reynolds genetic distances, Alpagota was the most differentiated, perhaps because it had been bred mostly in a rather isolated area. Loss of any of the investigated breeds would result in a loss of genetic diversity ranging from 0.5 to 1.6% of the total observed gene diversity. Results supported the decision to safeguard these breeds as important reservoirs of genetic diversity and suggested breeding and mating practices to maintain variability and to overcome within-breed substructures.