At the boundary between two woodrat species (Neotoma fuscipes and N. macrotis) in the Sierra Nevada foothills, drought has driven differential survival between the species and their hybrids, changing who is available to mate with whom. Using six years of field-measured parentage data, we show that as conspecific mates became scarcer, hybridization rates increased — but not symmetrically. Reproductive success was skewed between the parental lineages, F1 hybrid males had near-zero reproductive success, and nearly all surviving hybrids had one purebred parent, pointing to partial genomic incompatibility between the two species.
The study illustrates a subtle but important pathway by which climate change can reshape species boundaries: not just through range shifts, but by altering the demographic balance that determines who gets to mate with whom at a hybrid zone.
Citation: Matocq, M.D., Hunter, E.A., Murphy, P.J., Adkins, C.L., Shoemaker, K.T. 2024. Asymmetric mate preference and reproductive interference mediate climate-induced changes in mate availability in a small mammal hybrid zone. Evolution. https://doi.org/10.1093/evolut/qpae110