Results of Barrier analyses for B. rufescens and B. occidentalis . A) Four barriers between populations of B. rufescens, with Barrier a as the first barrier inferred and Barrier d as the last. Barrier a corresponds to a division between samples from Guatemala and all others; b separates some populations from Los Tuxtlas, c separates the remaining population from Los Tuxtlas, and d separates populations on either side of the Isthmus of Tehuantepec. B) For B. occidentalis, Barrier a separates populations from Guatemala and southeastern Chiapas from all others, Barrier b divides the Cerro Baul population and one population from the Berriozabal area from all others, and Barrier c separates populations from the Pacific coast of Guatemala and southeastern Chiapas from the single population in the El Triunfo area. Blue lines indicate polygons from Voronoi tessellation, green lines show Delaunay triangulation.