The spatial ecology of Mojave Rattlesnakes (Crotalus scutulatus), Prairie Rattlesnakes (C. viridis), and their hybrids in southwestern New Mexico

Hybridization between species provides unique opportunities to understand
evolutionary processes that are linked to reproductive isolation and,
ultimately, speciation. However, the extrinsic factors that limit
hybridization are poorly understood for most animal systems. Although the
spatial ecology of individuals in natural habitats is fundamental to
shaping reproductive success and survival, analyses of the spatial ecology
of hybrids and their parental groups are rarely reported. Here, we used
radiotelemetry to monitor wild rattlesnakes across an interspecific hybrid
zone (Crotalus scutulatus and Crotalus viridis) and measured movement
parameters and space use (utilization distributions) of individuals to
evaluate the hypothesis that hybridization resulted in transgressive or
atypical movement patterns. Unexpectedly, of the spatial metrics we
investigated, we found that hybrids were very similar to parental
individuals. Nonetheless, hybrids did show increased patchiness of core
utilization distributions, but this result is likely to be driven by
increased habitat patchiness in the hybrid zone. Overall, we did not find
evidence for overt extrinsic barriers to hybridization associated with
spatial ecology; thus, we suggest that the close evolutionary history
between the two parental species and their ecological and behavioural
similarities are likely to increases the probability of hybridization
events in this unique region of New Mexico.