Phylogenetic analysis of Tibetan mastiffs based on mitochondrial hypervariable region I

Area of Science:

• Genetics
• Zoology
• Conservation Biology

Background:

• Tibetan mastiffs, a valuable genetic resource and cultural heritage, face a sharp decline in numbers.
• Understanding their genetic diversity and phylogenetic relationships is essential for effective conservation and utilization.

Purpose of the Study:

• To investigate the genetic diversity and phylogenetic origins of Tibetan mastiffs.
• To provide a foundation for the protection and sustainable development of this breed.

Main Methods:

• Sequencing of the hypervariable region I of mitochondrial DNA (mtDNA) from 110 Tibetan mastiffs.
• Analysis of polymorphic sites, haplotype diversity, nucleotide diversity, and phylogenetic relationships.
• Median-joining network and phylogenetic tree construction.
• Mismatch distribution analysis and neutrality tests.

Main Results:

• Eight haplotypes were identified, with H4 and H8 unique to the Tibetan population.
• Tibetan mastiffs from Gansu exhibited higher genetic diversity (haplotype diversity: 0.808; nucleotide diversity: 0.603%) than those from the Tibet region (haplotype diversity: 0.794; nucleotide diversity: 0.589%).
• Overall genetic variation within the total population was low.
• Phylogenetic analysis confirmed Tibetan mastiffs originated from grey wolves, with a distinct maternal lineage.
• Population analysis suggested Tibetan mastiffs are in genetic equilibrium or experiencing a decline.

Conclusions:

• Tibetan mastiffs possess lower overall genetic diversity, with higher diversity observed in Gansu populations.
• The breed originated from grey wolves, sharing a common maternal ancestry with other domestic dogs.
• Evidence suggests a state of genetic equilibrium or population decline, highlighting the urgency for conservation strategies.