Patterns, Predictors, and Consequences of Dominance in Hybrids

Area of Science:

• Evolutionary biology
• Genetics
• Quantitative genetics

Background:

• Understanding first-generation (F1) hybrid phenotypes is crucial for evolutionary and breeding studies.
• Empirical data on whether F1 traits are intermediate, parent-biased, or mismatched is limited.

Purpose of the Study:

• To determine the phenotypic relationship of F1 hybrids to their parental taxa.
• To investigate the fitness consequences of parent bias and trait mismatch in F1 hybrids.

Main Methods:

• Compiled data from 233 crosses measuring traits in parents and F1 hybrids in a common environment.
• Analyzed bivariate phenotypes for parent bias and mismatch.
• Utilized field planting data of recombinant hybrid sunflowers to assess fitness.

Main Results:

• Individual F1 traits were not intermediate but showed a bias towards one parent.
• Bivariate phenotypes exhibited significant parent bias and trait mismatch.
• Parent bias was associated with improved fitness, while mismatch reduced fitness.

Conclusions:

• F1 hybrids display substantial phenotypic mismatch rather than intermediate traits.
• Dominance patterns are shaped by individual trait and population evolutionary histories.
• Selection against hybrids is likely driven by both intermediate and mismatched phenotypes.