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Abstract 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 increase the probability of hybridization events in this unique region of New Mexico.
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Hybridization in the absence of an ecotone favors hybrid success in woodrats ( Neotoma spp.)
Abstract Hybridization is a common process that has broadly impacted the evolution of multicellular eukaryotes; however, how ecological factors influence this process remains poorly understood. Here, we report the findings of a 3-year recapture study of the Bryant’s woodrat (Neotoma bryanti) and desert woodrat (Neotoma lepida), two species that hybridize within a creosote bush (Larrea tridentata) shrubland in Whitewater, CA, USA. We used a genotype-by-sequencing approach to characterize the ancestry distribution of individuals across this hybrid zone coupled with Cormack–Jolly–Seber modeling to describe demography. We identified a high frequency of hybridization at this site with ~40% of individuals possessing admixed ancestry, which is the result of multigenerational backcrossing and advanced hybrid-hybrid crossing. F1, F2, and advanced generation hybrids had apparent survival rates similar to parental N. bryanti, while parental and backcross N. lepida had lower apparent survival rates and were far less abundant. Compared to bimodal hybrid zones where hybrids are often rare and selected against, we find that hybrids at Whitewater are common and have comparable survival to the dominant parental species, N. bryanti. The frequency of hybridization at Whitewater is therefore likely limited by the abundance of the less common parental species, N. lepida, rather than selection against hybrids.
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- Award ID(s):
- 1656497
- PAR ID:
- 10491596
- Publisher / Repository:
- Evolution
- Date Published:
- Journal Name:
- Evolution
- Volume:
- 77
- Issue:
- 4
- ISSN:
- 0014-3820
- Page Range / eLocation ID:
- 959-970
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/evolut/qpad012
