Identification and analysis of the genetic diversity of Dermacentor everestianus using mitochondrial 16S rRNA and COI sequences in the Xizang Autonomous Region of China

Ticks serve as vectors and reservoirs for a variety of pathogens, including protozoa, bacteria, and viruses, that cause tick-borne diseases in both humans and livestock. Despite their widespread distribution, their genetic diversity and population structure in Xizang have not been thoroughly investigated. In this study, sheep ticks were identified from four counties by microscopy, followed by genetic analysis of Dermacentor everestianus populations in Xizang based on mitochondrial 16S rRNA and cytochrome oxidase subunit 1 (COI) gene sequences. D. everestianus was the predominant species and 16S rRNA gene sequence analysis revealed nine haplotypes with seven nucleotide variations, showing a mean haplotype diversity (H_d) of 0.505 and mean nucleotide diversity (P_i) of 0.00129. Similarly, the COI sequences revealed 28 haplotypes with 26 nucleotide variations, yielding a mean H_d of 0.828 and a mean P_i of 0.00279. Molecular variance analysis (AMOVA) indicated that most genetic variation occurs within populations. In addition, neutral test analyses suggested potential bottleneck events in the D. everestianus populations. The haplotype network had a star-like distribution with the common haplotypes A1, A2, B1, and B5. The phylogenetic tree separated haplotypes of both genes into two branches on the haplotype network indicating no distinct geographical clustering. This study is the first to highlight the prevalence of D. everestianus in Xizang, revealing moderate genetic differentiation among the four populations, possibly due to host mobility. This intensive investigation of genetic variation and population structure contributes valuable insights into the current population genetics of D. everestianus in Xizang, China.