Variable hybridization outcomes in trout are predicted by historical fish stocking and environmental context

Molecular Ecology
By: , and 

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Abstract

Hybridization can profoundly affect the genomic composition and phenotypes of closely related species, and provides an opportunity to identify mechanisms that maintain reproductive isolation between species. Recent evidence suggests that hybridization outcomes within a species pair can vary across locations. However, we still don’t know how extensive variation in outcomes of hybridization is across geographic replicates, and what mechanisms drive that variation. In this study, we described hybridization outcomes across 27 locations in the North Fork Shoshone River basin (Wyoming, USA) where native Yellowstone cutthroat trout and introduced rainbow trout co-occur. We used genomic data and hierarchical Bayesian models to precisely identify ancestry of hybrid individuals. Hybridization outcomes varied across locations. In some locations, only rainbow trout and advanced backcrossed hybrids towards rainbow trout were present, while other locations had a broader range of ancestry, including both parental species and first-generation hybrids. Using an individual-based simulation, we found that outcomes of hybridization in the North Fork Shoshone River basin deviate substantially from what we would expect under assumptions of random mating and no selection against hybrids. Since this implies that some mechanisms of reproductive isolation function to maintain parental taxa and a diversity of hybrid types, we then modeled hybridization outcomes as a function of environmental variables and stocking history that are likely to affect prezygotic barriers to hybridization. Variables associated with history of fish stocking were the strongest predictors of hybridization outcomes, followed by environmental variables that might affect overlap in spawning time and location.

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Publication type Article
Publication Subtype Journal Article
Title Variable hybridization outcomes in trout are predicted by historical fish stocking and environmental context
Series title Molecular Ecology
DOI 10.1111/mec.15175
Volume 28
Issue 16
Year Published 2019
Language English
Publisher Wiley
Contributing office(s) Coop Res Unit Seattle
Description 18 p.
First page 3738
Last page 3755
Country United States
State Wyoming
Other Geospatial Buffalo Bill Reservoir, North Fork Shoshone River basin
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