Isolation over time in Texas collections of Rhipicephalus microplus . Tick samples include collections from cattle and white-tailed deer. Panel a) pairwise FST comparisons over time within seven individual properties (see Table 1, collection subset “TA”). Each individual point is a pairwise θ value between two collections at a single property, which controls for spatial variation. Filled pink triangles denote pairwise comparisons within Prop11 in Zapata Co.; filled blue squares denote pairwise comparisons within Prop34 in Starr Co.; open circles represent pairwise comparisons within five other properties sampled over shorter time intervals. Panel b) pairwise FST comparisons for collections sampled within a 4 km neighborhood around Prop11 (Zapata Co.) or Prop34 (Starr Co.) (see Table 1, collection subset “TB”). Symbol definitions are the same as for Panel a, with the following additions: open pink triangles denote all pairwise θ values among collections near Prop11; open blue squares denote all pairwise θ values among collections near Prop34.