Genetic characterization of the Miyako horse based on polymorphisms of microsatellites and mitochondrial DNA.
Abstract: To help plan conservation of the endangered Miyako horse, a biological resource of the Miyako Islands in Japan, we characterized the genetics of the breed by genotyping 32 microsatellites and identifying mitochondrial DNA haplotypes. We also calculated genetic distances between individuals based on the proportion of shared alleles and visualized the genetic relationships with a phylogenetic tree. Two important results were obtained. One is that accurate pedigree registration of the horse by using microsatellites is possible, as the exclusion power of parentage testing is 0.999998. Another is that the current genetic diversity of the horses was clarified. The average number of alleles, observed heterozygosity and expected heterozygosity were 4.2, 0.701 and 0.649, respectively, for the 35 analyzed horses. The probability values for bottleneck models (infinite allele model: 0.00000; stepwise mutation model: 0.00026; and two-phase model: 0.00000) suggested that Miyako horses have experienced a recent genetic bottleneck. Only one mitochondrial haplotype was identified. Consequently, genetic diversity within the population is relatively well-maintained despite a very small population size (41 at the time of the study), and the first priority in conservation of the Miyako horse is to increase the population size.
Publication Date: 2016-10-28 PubMed ID: 27795462PubMed Central: PMC5289264DOI: 10.1292/jvms.16-0111Google Scholar: Lookup
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Summary
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This research is about the genetic characterization of the endangered Miyako horse breed in Japan using microsatellites and mitochondrial DNA. The researchers identified the limits of genetic diversity within the population and concluded that, despite its small size, the population’s diversity is fairly maintained. This hence highlights the need to increase the population size as a priority in conservation efforts.
Research Methodology
- The researchers involved in the study collected genetic data from 32 microsatellites and mitochondrial DNA in order to better understand the genetic makeup of the Miyako horse breed.
- Using this data, they calculated genetic distances between individual horses by examining the proportion of shared alleles (different forms of a specific gene).
- The genetic relationships were then visualized through the construction of a phylogenetic tree, a diagram that shows evolutionary relationships based on genetic similarity.
Findings
- The first key finding is regarding pedigree verification. The researchers found that microsatellites can be used to accurately verify the pedigree of the horses, with a very high exclusion power of parentage testing (0.999998).
- The second important discovery pertains to an understanding of the current genetic diversity within the Miyako horses population. The average number of alleles, observed heterozygosity (ratio of heterozygous individuals, that have two different versions of a particular gene, to all individuals), and expected heterozygosity were found to be 4.2, 0.701 and 0.649 respectively among the 35 horses analyzed.The high observed heterozygosity despite a limited pool of alleles suggests maintained genetic diversity.
- The researchers also performed tests to identify whether the Miyako horse population had experienced a genetic bottleneck (a sharp reduction in population size due to environmental events, leading to a decrease in genetic diversity). The probability values for genetic bottleneck models suggested that the Miyako horses had indeed experienced a recent genetic bottleneck.
- Additionally, the researchers found that there was only one mitochondrial haplotype (a group of genes within an organism that were inherited together from a single parent) in the entire population. This indicates a lack of variation in the inherited genetic material.
Conclusion
- The researchers concluded that despite the small population of the Miyako horse (41 at the time of the study), the genetic diversity within the population remains fairly maintained.
- However, due to the evidence of a recent genetic bottleneck and the presence of only one mitochondrial haplotype, the researchers suggest that in order to ensure the conservation of the Miyako horse, efforts should first be focused on increasing the population size.
Cite This Article
APA
Senju N, Tozaki T, Kakoi H, Almunia J, Maeda M, Matsuyama R, Takasu M.
(2016).
Genetic characterization of the Miyako horse based on polymorphisms of microsatellites and mitochondrial DNA.
J Vet Med Sci, 79(1), 218-223.
https://doi.org/10.1292/jvms.16-0111 Publication
Researcher Affiliations
- Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
MeSH Terms
- Alleles
- Animals
- DNA, Mitochondrial / genetics
- Endangered Species
- Female
- Genotyping Techniques / veterinary
- Haplotypes / genetics
- Horses / genetics
- Japan
- Male
- Microsatellite Repeats / genetics
- Phylogeny
- Polymorphism, Genetic / genetics
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Citations
This article has been cited 7 times.- Masuda M, Nikadori A, Nikadori E, Uchida N, Takizawa Y, Ishimaru M, Yamamoto T, Yuasa R, Kugai H, Nagahama Y, Takasu M, Tozaki T. Evaluation of genetic diversity using 31 microsatellites in Miyako horses.. J Equine Sci 2023 Mar;34(1):1-6.
- Yoshihara T, Kikuchi M, Akiba Y, Horiguchi M, Takasu M, Tozaki T. Genetic diversity analysis and parentage verification of Taishu horses using 31 microsatellites.. J Equine Sci 2022 Dec;33(4):63-69.
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