What Is Going on with the Genus Dermacentor? Hybridizations, Introgressions, Oh My!

ORCID

Goddard: https://orcid.org/0000-0002-2617-7141; Moraru: https://orcid.org/0000-0002-4361-7540

MSU Affiliation

College of Agriculture and Life Sciences; Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology

Creation Date

2026-09-30

Abstract

In the 1930s, R. A. Cooley noted that Dermacentor occidentalis (Acarina: Ixodidae) and Dermacentor andersoni were closely related and could hybridize. Decades later, James Oliver discovered that crosses of Dermacentor variabilis, D. andersoni, and D. occidentalis could, on occasion, produce hybrids. A recent molecular analysis (both mtDNA and nDNA) in our laboratory revealed that certain specimens of Dermacentor andersoni nested with Dermacentor parumapertus. Does this close relationship, along with the mito-nuclear discordance we have observed, mean D. andersoni and D. parumapertus are a single species? By contemporary taxonomic criteria, this seems improbable based on their distinctly different morphologies, host associations, and ecologies. This paper explores ideas related to mito-nuclear discordance, hybridization, and introgression (primarily) not only in these two species but also other members of the genus Dermacentor. Both D. andersoni and D. parumapertus can be found on the same hosts and have sympatric distributions, so introgression of genetic material by occasional cross-mating between these two species is possible. Further, the difficulty in applying specific species concepts in ticks has been recently pointed out and a unified agreement on an integrative species concepts could clearly be useful in this situation. With the discovery of D. parumapertus as a potential vector of Rickettsia parkeri and the historically recognized role of D. andersoni in transmission of Rickettsia rickettsii, understanding the specific status of each lineage of these species (and others in the genus) is extremely important from a public health perspective.

Keywords

Dermacentor andersoni, Dermacentor parumapertus, hybridization, introgression, mito-nuclear discordance

Publication Date

11-26-2019

Publication Title

Journal of Medical Entomology

Publisher

Oxford University Press; Entomological Society of America

First Page

653

Last Page

656

Rights

© The Author(s) 2019

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Digital Object Identifier (DOI)

https://doi.org/10.1093/jme/tjz219