Genetic diversity and structure of the West Balkan Pramenka sheep types as revealed by microsatellite and mitochondrial DNA analysis

Abstract

Several different phenotypes of the native Pramenka sheep have been developed in the Balkan region for different environmental and socio-cultural conditions. Animals from seven West Balkan Pramenka sheep types were analysed for 15 microsatellite markers and for mitochondrial DNA (mtDNA) and the results were used to assess genetic variation within and among the types and to infer the genetic population structure of the Pramenka sheep. Mean expected heterozygosity and allelic richness over the microsatellite loci and sheep types were 0.78 and 7.9, respectively. A Bayesian statistical method for estimating hidden genetic structure suggested that a core of the largest panmictic population was formed by Serbian, Kosovan, Bosnian, Montenegrin and Albanian types, while Croatian and Macedonian types comprised two other main populations, respectively. Mitochondrial DNA analysis revealed two mtDNA haplogroups in the Pramenka sheep, B and A, with a frequency of 93.7% and 6.3%, respectively. A total of 60 mtDNA haplotypes were found in 64 animals sequenced, and the mean nucleotide and haplotypic diversities over the types were 0.013 and 0.945, respectively. Molecular analysis suggests that the West Balkan Pramenka sheep types have their origins in two distinct maternal lineages of domestic sheep and different Pramenka phenotypes tend to form few panmictic populations. The Pramenka sheep represents a valuable resource of genetic diversity in sheep.

Genetic diversity and differentiation of 12 eastern Adriatic and western Dinaric native sheep breeds using microsatellites

“…Moderate genetic variation component estimated between the studied populations (5.29%) was similar to values reported for other Balkan sheep (Cínkulov et al, 2008), and somewhat higher than those reported for Greek breeds (Ligda et al, 2009). The low percentages of the variance explained by utility-wise (0.008, P < 0.01) and geography-wise (0.006, P < 0.05) grouping, compared with results reported in Indian sheep (Arora et al, 2011), suggest a low influence of specific selection strategies, but also a poor influence of the geographical isolation in the overall sampling area.…”

“…Except for OarFCB128, these markers showed no correlation to the occurrence of null alleles and can be explained by a reduced effective size of the flocks in the studied populations. Although a comparison of the genetic diversity parameters described here with those reported in other populations is difficult because of different markers and sample sizes used, our results indicate values similar to those reported for the Balkan pramenka breeds (Cínkulov et al, 2008). In general, our analyses revealed higher within-breed variability than reported for selected breeds such as Sarda sheep, as expected for sheep populations that have not been highly pressured by selection (Arranz et al, 2001;Pariset et al, 2003).…”

“…Moreover, we found that sheep genetic diversity in this south European region was not lost, with values fitting the pattern of radiation of genetic variation from the Near East hot-spot (Tapio et al, 2010). For example, we found the MNA (range 6.03 to 8.6) to be within the range reported for Balkan pramenka breeds (Cínkulov et al, 2008) and alpine sheep (Dalvit et al, 2008). However, it was lower than that reported for Greek (Ligda et al, 2009) and Turkish sheep breeds (Gutierrez-Gil et al, 2006).…”

“…As reported in Cínkulov et al (2008), IST group can be considered as a distinct breed, but VLA is clustering with other Balkan pramenka populations. Factorial correspondence and structure analysis showed that LIK, CRE and IST are the most distinct groups.…”

“…Differentiation and neutral nuclear diversity studies are scarce and have been reported only in a limited number of these pramenka populations (Bradic et al, 2003;Lawson Handley et al, 2007;Cínkulov et al, 2008) using different sets of markers, which makes comparison of results between breeds and with other breeds difficult (Food and Agriculture Organization of the United Nations, 2011). Ancestral origin using mtDNA and Y chromosome data has also been investigated in Pramenka sheep (Bradic et al, 2005;Ivanković et al, 2005;Ferencakovic et al, 2013).…”