Differences in dietary composition and preference maintained despite gene flow across a woodrat hybrid zone

1. Hybridization can homogenize the gene pools of species that come into secondary contact. Alternatively, species differentiation can persist despite hybridization and interspecific gene flow. When hybridization occurs across sharp environmental transitions (i.e. ecotones), spatial variation in selection may reduce interspecific gene flow through pre- and post-zygotic isolating mechanisms. Ecotones, characterized by adjacent yet distinct biotic communities, provide natural laboratories in which to investigate how environmental selection influences the ecology and evolution of organisms. For wild herbivores, differential plant availability across sharp ecotones may be an important source of dietary-based selection.

2. We studied small herbivore diet composition across a sharp ecotone where two species of woodrat, Neotoma bryanti and N. lepida, come into secondary contact with one another and hybridize. We quantified woodrat dietary preference through trnL metabarcoding of field-colle...