Adaptive evolution of the mitochondrial ND6 gene in the domestic horse.
Abstract: Mitochondria play a crucial role in energy metabolism through oxidative phosphorylation. Organisms living at high altitudes are potentially influenced by oxygen deficits and cold temperatures. The severe environmental conditions can impact on metabolism and direct selection of mitochondrial DNA. As a wide-ranging animal, the domestic horse (Equus caballus) has developed various morphological and physiological characteristics for adapting to different altitudes. Thus, this is a good species for studying adaption to high altitudes at a molecular level. We sequenced the complete NADH dehydrogenase 6 gene (ND6) of 509 horses from 24 sampling locations. By comparative analysis of three horse populations living at different altitudes (>2200 m, 1200-1700 m, and <900 m), we found that the high-altitude population had the lowest genetic diversity and significant negative Tajima's D; both values declined with increasing elevation. Moreover, non-directional selection was identified for the ND6 gene by a tree-based relative ratio test (P = 0.007); the highest proportion of high-altitude horses was found distributed on the selected branches. We conclude that the high-altitude environment has directed adaptive evolution of the mitochondrial ND6 gene in the plateau horse.
Publication Date: 2010-01-26 PubMed ID: 20198570DOI: 10.4238/vol9-1gmr705Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article shows how the mitochondrial ND6 gene has adaptively evolved in domestic horses living at high altitudes. This adaptive evolution is thought to be a result of the harsh environmental conditions found at high altitudes.
Objective of the Research
- The main objective of this study was to examine the adaptation to high altitudes at the genetic level in domestic horses. The research focused on the ND6 gene, which is part of the mitochondrial DNA and plays a crucial role in energy metabolism. A better understanding of these genetic adaptations can potentially enhance our understanding of how organisms adjust to harsh environments.
Methodology
- The researchers examined the ND6 genes of 509 horses from 24 different locations. These locations were categorized based on the altitude at which the horses reside: high-altitude of over 2200 meters, mid-altitude of between 1200-1700 meters, and low altitude of less than 900 meters.
- Genetic diversity among the horse populations at different altitudes was measured, and comparative analysis was conducted.
- Tree-based relative ratio tests were used to identify the presence of non-directional selection for the ND6 gene among these populations.
Findings
- The researchers found that horses living in the high-altitude areas had the lowest genetic diversity and a significant negative Tajima’s D value, which is a measure of variation in DNA sequences. Both of these features decreased as the elevation increased.
- Through the tree-based relative ratio test, they identified non-directional selection of the ND6 gene among the horse populations.
- Interestingly, most horses living at high altitudes were found distributed on the selected branches, indicating a strong correlation between the adapted gene and high-altitude living.
Conclusion
- Based on these findings, the research concluded that the harsh environment at high altitudes has led to the adaptive evolution of the mitochondrial ND6 gene in domestic horses. This suggests that natural selection at high altitudes favours those horses with specific variations in the ND6 gene that perhaps enable better energy metabolism under low oxygen and cold conditions.
Cite This Article
APA
Ning T, Xiao H, Li J, Hua S, Zhang YP.
(2010).
Adaptive evolution of the mitochondrial ND6 gene in the domestic horse.
Genet Mol Res, 9(1), 144-150.
https://doi.org/10.4238/vol9-1gmr705 Publication
Researcher Affiliations
- Laboratory for Conservation and Utilization of Bio-Resource, Yunnan University, Kunming, Yunnan, China.
MeSH Terms
- Altitude
- Animals
- China
- Evolution, Molecular
- Genes, Mitochondrial / genetics
- Genetic Variation
- Horses / genetics
- Likelihood Functions
- NADH Dehydrogenase / genetics
- Phylogeny
- Selection, Genetic
Citations
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