Exploring the Origin and Relatedness of Maternal Lineages Through Analysis of Mitochondrial DNA in the Holstein Horse

Mitochondrial DNA and Y chromosome reveal the genetic structure of the native Polish Konik horse population

Polish Konik remains one of the most important horse breeds in Poland. The primitive, native horses with a stocky body and mouse-like coat color are protected by a conservation program, while their Polish population consists of about 3,480 individuals, representing 16 dam and six sire lines. To define the population's genetic structure, mitochondrial DNA and Y chromosome sequence variables were identified. The mtDNA whole hypervariable region analysis was carried out using the Sanger sequencing method on 233 Polish Koniks belonging to all dam lines, while the Y chromosome analysis was performed with the competitive allele-specific PCR genotyping method on 36 horses belonging to all sire lines. The analysis of the mtDNA hypervariable region detected 47 SNPs, which assigned all tested horses to 43 haplotypes. Most dam lines presented more than one haplotype; however, five dam lines were represented by only one haplotype. The haplotypes were classified into six (A, B, E, J, G, R) recognized mtDNA haplogroups, with most horses belonging to haplogroup A, common among Asian horse populations. Y chromosome analysis allocated Polish Koniks in the Crown group, condensing all modern horse breeds, and divided them into three haplotypes clustering with coldblood breeds (28 horses), warmblood breeds (two horses), and Duelmener Pony (six horses). The clustering of all Wicek sire line stallions with Duelmener horses may suggest a historical relationship between the breeds. Additionally, both mtDNA and Y chromosome sequence variability results indicate crossbreeding before the studbooks closure or irregularities in the pedigrees occurred before the DNA testing introduction.

Phylogeographic and population genetic structure of hound-like native dogs of the Mediterranean Basin

The dog was probably the first domesticated animal. Despite extensive archaeological and genetic investigations, the origin and the evolution of the extant dogs are still being debated. Dog breeds that have over time been selected for hunting share common ancestral traits. This study represents the first comprehensive attempt to survey at the genomic and mitochondrial level eight hound-like dogs breeds indigenous to the Mediterranean Basin to determine if they share common ancient origins. Results from the microsatellite analysis indicate that all the dog populations have a low inbreeding value.The Kelb tal-Fenek has a high divergence from the current Egyptian street population, however there is not enough evidence from this study to exclude completely the potential of an ancient common relationship. Overall, the mitochondrial results indicate high frequencies of haplogroups A and B and a low representation of haplogroup C, while only one Egyptian dog could be assigned to haplogroup D. Results reveal identities and shared clades, suggesting the conservation of ancient European mitotypes in the Mediterranean hound-like breeds, especially in the Egyptian population. Although none of the dog populations/breeds participating in this study indicate to be direct descendants of the Egyptian dogs, they still have a very close morphologically resemblance to those iconic Egyptian dogs often depicted in ancient art forms and share some genetic links with the current Egyptian population. Further research is required with other markers such us complete mitogenomes and SNP panels to confirm the complex history of the Mediterranean dogs involved in this study.

Mitochondrial DNA Variation Contributes to the Aptitude for Dressage and Show Jumping Ability in the Holstein Horse Breed

Maternal lineages are considered an important factor in breeding. Mitochondrial DNA (mtDNA) is maternally inherited and plays an important role in energy metabolism. It has already been associated with energy consumption and performances, e.g., stamina in humans and racehorses. For now, corresponding studies are lacking for sport performance of warmblood breeds. MtDNA sequences were available for 271 Holstein mares from 75 maternal lineages. As all mares within a lineage showed identical haplotypes regarding the non-synonymous variants, we expanded our data set by also including non-sequenced mares and assigning them to the lineage-specific haplotype. This sample consisting of 6334 to 16,447 mares was used to perform mitochondrial association analyses using breeding values (EBVs) estimated on behalf of the Fédération Équestre Nationale (FN) and on behalf of the Holstein Breeding Association (HOL). The association analyses revealed 20 mitochondrial SNPs (mtSNPs) significantly associated with FN-EBVs and partly overlapping 20 mtSNPs associated with HOL-EBVs. The results indicated that mtDNA contributes to performance differences between maternal lineages. Certain mitochondrial haplogroups were associated with special talents for dressage or show jumping. The findings encourage to set up innovative genetic evaluation models that also consider information on maternal lineages.