Haplotype network analyses, genetic diversity, and population structure of Hyalomma anatolicum based on cytochrome c oxidase subunit I (COI) and the large subunit ribosomal RNA (16S rRNA).

Among the Ixodid ticks, Hyalomma anatolicum is a well-known vector that transmits various pathogens to terrestrial and semi-terrestrial vertebrates including humans, and its population differ in ecology and vector competence. Expansion of this tick to new areas changes the genetic structure, and lead to affect the vector-pathogen interaction and disease outcomes. The present study was designed to infer the haplotype diversity, demographic dynamics, gene flow and genetic differentiation, and phylogeny of H. anatolicum from different countries based on the cytochrome oxidase I (COI) and 16S rDNA sequences. A total of 320 ticks were collected from cattle, buffaloes, and sheep in five districts of Khyber Pakhtunkhwa, Pakistan, morphologically identified as H. anatolicum, and subjected to genetic analysis. A total 85 and 138 sequences for COI and 16S rDNA, including 11 and 2 sequences generated in this study, respectively, were analyzed to assess haplotype network, population structure and divergence, demographic changes, and phylogenetic analysis. Analysis based on COI sequences yielded 29 haplotypes in which haplotype 1 and 15 were the predominant consisting of 35 and 20 sequences, respectively, from Pakistan, India, China, Bangladesh, Iraq, Saudi Arabia, Kazakhstan and Egypt. The 16S rRNA yielded 30 haplotypes in which haplotype 1 was predominant consisting of total 86 sequences from Pakistan, India, China, United Arab Emirates, Tajikistan, Kazakhstan, Turkey, Egypt, and Iraq. Complete haplotype network based on COI and 16S rRNA confirmed stellate structure, together with high haplotype diversity (COI 0.77899, 16S rRNA 0.60774) and low nucleotide diversity (COI 0.00445, 16S rRNA 0.00431), which support recent population expansion. Similarly, neutrality indices for the whole dataset, Tajima's D (COI - 2.36363**, 16S rRNA - 2.54127***), Fu and Li's D (COI - 5.72992, 16S rRNA - 6.31313*), and Fu and Li's F (COI - 5.04435*, 16S rRNA - 5.56085*) were negative, indicating deviation from neutrality and recent population dispersal. In the phylogenetic tree based on the COI and 16S rDNA sequences, with exception of one sequence for a single haplotypes, which appeared independently, there is a single main clade that includes the largest number of sequences for all other haplotype. Based on COI and 16S rDNA sequences, the present study provided first detail information about the population genetics and haplotype networks of H. anatolicum.