Genetic Variability and Population Structure in the Sardinian Anglo-Arab Horse

SIMPLE SUMMARY: It is known that animal populations might be affected by bottleneck phenomena, which reduce genetic variability, increase inbreeding and consequentially reduce evolutionary potential. Pedigree completeness, genetic variability and population structure were analyzed in the Sardinian Anglo-Arab horse (SAA) breed, and the analyzed results were compared with three other Italian horse populations: Maremmano, Murgese and Bardigiano (reported in bibliography). In addition, the maternal lineage was analyzed through mitochondrial DNA in order to preserve and improve the breed. The estimated parameters suggest that the SAA breed is well managed, especially when considering the female lineage because it still conserves a high number of founder mares. The role of breeding programs in the conservation of genetic diversity is essential. In fact, a breeding program might lead to fast genetic progress; however, it might also lead to a high level of inbreeding and consequently to a genetic drift. Analyzing both these parameters and the additional use of mitochondrial DNA might be an effective tool not only to verify the success of a breeding program, but also to be helpful for breeders on planning effective mating programs. ABSTRACT: The Sardinian Anglo Arab (SAA) is a famous horse breed in Italy, with a significant historical background in the island of Sardinia. The aim of the study is to perform an evaluation of genetic variability in SAA using pedigree and mitochondrial data. In the current population, pedigree completeness was observed to be close to 100%, while the inbreeding coefficient and the average relatedness were lower than 3%. The ratio of effective founders/numbers of ancestors was 3.68 for the whole pedigree. The effective population size (N(e)) computed by an individual increase in inbreeding (N(e_1)) was 456.86, the N(e) on equivalent generations (N(e_2)) was 184.75, and this value slightly increased to 209.31 when computed by log-regression on equivalent generations (N(e_3)). These results suggest the presence of crossbreeding and bottleneck phenomena, and they were compared with other Italian horses (reported in bibliography) to present the SAA among the Italian horse breeds scenario. Furthermore, the noteworthy mitochondrial variability reflects the use of a considerable number of founder mares; the contribution of L lineage was very important, probably because of the re-colonization from the Iberian Peninsula after the Last Glacial Maximum.