Data from: Temporal and spatial dynamics of competitive parapatry in chewing lice

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/y. 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.