Temporal and spatial dynamics of competitive parapatry in chewing lice

• Published in: Ecology and evolution Vol. 9; no. 13; pp. 7410 - 7424
• Main Authors: Hafner, David J., Hafner, Mark S., Spradling, Theresa A., Light, Jessica E., Demastes, James W.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01-07-2019; John Wiley and Sons Inc; Wiley
• Subjects: Chewing; chewing lice; Climate change; contact zones; dispersal distance; Flood control; Flood predictions; Floods; Garyops centralis; Geomyidae; Historical account; hybrid zones; Hybridization; Lice; Mastication; Original Research; Parasites; Phthiraptera; pocket gophers; Species; species replacement; Studies; New Mexico; Great Basin; hybrid zones; dispersal distance; chewing lice; pocket gophers; contact zones; species replacement
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.5183

We synthesize observations from 1979 to 2016 of a contact zone involving two subspecies of pocket gophers (Thomomys bottae connectens and T. b. opulentus) and their respective chewing lice (Geomydoecus aurei and G. centralis) along the Río Grande Valley in New Mexico, U.S.A., to test predictions about the dynamics of the zone. Historically, the natural flood cycle of the Rio Grande prevented contact between the two subspecies of pocket gophers. Flood control measures completed in the 1930s permitted contact, thus establishing the hybrid zone between the pocket gophers and the contact zone between their lice (without hybridization). Since that time, the pocket gopher hybrid zone has stabilized, whereas the northern chewing louse species has replaced the southern louse species at a consistent rate of ~150 m/year. The 0.2–0.8 width of the replacement zone has remained constant, reflecting the constant rate of chewing louse species turnover on a single gopher and within a local pocket gopher population. In contrast, the full width of the replacement zone (northernmost G. centralis to southernmost G. aurei) has increased annually. By employing a variety of metrics of the species replacement zone, we are better able to understand the dynamics of interactions between and among the chewing lice and their pocket gopher hosts. This research provides an opportunity to observe active species replacement and resulting distributional shifts in a parasitic organism in its natural setting.
We synthesize observations from 1979 to 2016 of a contact zone involving two subspecies of pocket gophers (Thomomys bottae connectens and T. b. opulentus) and their respective chewing lice (Geomydoecus aurei and G. centralis) along the Río Grande Valley in New Mexico, U.S.A., to test predictions about the dynamics of the zone. By employing a variety of metrics of the species replacement zone, we are able to analyze detailed interactions between and among the chewing lice and their pocket gopher hosts. This research provides an opportunity to observe active species replacement and resulting distributional shifts in a parasitic organism in its natural setting.