Hybridization in natural sympatric populations of Dermacentor ticks in northwestern North America

• Published in: Ecology and evolution 2013-03, Vol.3 (3), p.714-724
• Main Authors: Araya‐Anchetta, A., Scoles, G. A., Giles, J., Busch, J. D., Wagner, D. M.
• Format: Article
• Language: English
• Subjects: Amplified fragment length polymorphism; Animal behavior; Arachnids; D. variabilis; Dermacentor; Dermacentor andersoni; Gene flow; Genetic structure; Hybridization; Hybrids; Ixodidae; Laboratories; Loci; Mitochondrial DNA; Original Research; Polymorphism; Population; Population genetics; Population structure; Populations; Roads & highways; Rodents; Species; Sympatric populations; Ticks
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.496

Hybridization in ticks has been described in a handful of species and mostly as a result of laboratory experiments. We used 148 AFLP loci to describe putative hybridization events between D. andersoni and D. variabilis in sympatric populations from northwestern North America. Recently, D. variabilis has expanded its range westward into the natural range of D. andersoni. Using a sample of 235 D. andersoni and 62 D. variabilis, we identified 31 individuals as putative hybrids: four F2 individuals and 27 backcrosses to D. andersoni (as defined by NewHybrids). We found no evidence of hybrids backcrossing into D. variabilis. Furthermore, all hybrids presented 16S mtDNA signatures characteristic of D. andersoni, which indicates the directionality of the hybrid crosses: female D. andersoni × male D. variabilis. We also discovered 13 species‐specific AFLP fragments for D. andersoni. These loci were found to have a decreased occurrence in the putative hybrids and were absent altogether in D. variabilis samples. AFLP profiles were also used to determine the levels of genetic population structure and gene flow among nine populations of D. andersoni and three of D. variabilis. Genetic structure exists in both species (D. andersoni, ΦST = 0.110; D. variabilis, ΦST = 0.304) as well as significant estimates of isolation by distance (D. andersoni, ρ = 0.066, P = 0.001; D. variabilis, ρ = 0.729, P = 0.001). We describe putative hybridization events between Dermacentor andersoni and D. variabilis in sympatric populations from Northwestern North America. Using a sample of 235 D. andersoni and 62 D. variabilis, we identified 31 individuals as putative hybrids: four F2 individuals and 27 backcrosses to D. andersoni. We found no evidence of hybrids backcrossing into D. variabilis.