Investigation of genetic diversity of Ixodes ricinus ticks based on mitochondrial DNA and microsatellite markers

Abstract

The application of molecular markers to the study of ticks has recently provided new insights into their population structures and phylogenetic relationships (Navajas and Fenton 2000). Use of microsatellites as genetic markers in population genetic studies has increased rapidly over the last years including several species of Ixodidae (Roed et al. 2006). Mitochondrial DNA (mtDNA) markers have also proved popular for studying of the systematic of ticks and their population structure. The aim of this study was to evaluate genetic diversity of I. ricinus ticks in Baltic countries using mtDNA and microsatellites markers. We screened three mitochondrial gene sequences 16S rRNA, cytb and control region sequences among 35 I.ricinus and ticks, collected from 16 locations: in Lithuania (4 locations), Latvia (4), Estonia (7) and Slovakia (1). Cytb gene was the most conservative gene that had only 4 haplotypes in Baltic countries, with control region sequences was detected 13 haplotypes and the most haplotypes (16 haplotypes) was detected in 16S rRNR gene sequences. We used four microsatellite loci for investigation of genetic diversity among 180 I.ricinus and ticks, collected from 16 locations in Lithuania (6 locations), Latvia (5) and Estonia (5). A total of 79 alleles were detected: the highest number of alleles per locus (25) was observed in samples from Latvia, followed in samples from Lithuania (20), and the lowest in samples from Estonia (18). The number of observed alleles between loci ranged from 5 to 10, and the observed heterozigosities between 0.2 and 0.8. Analysis of molecular variance (AMOVA) showed that genetic diversity of I. ricinus within sampling locations yielded 79%, and among locations 21% of the total genetic diversity. The PCA analysis not revealed distinct clustering for samples from different locations. Samples of different origin showed to a varying extent overlaps.