Data from: A test of hybrid growth disadvantage in wild, free-ranging species pairs of threespine sticklebacks (Gasterosteus aculeatus) and its implications for ecological speciation

Reduced performance of hybrids in nature is thought to be an important process by which natural selection can favour the evolution of assortative mating and drive speciation. Benthic and limnetic sympatric species of threespine stickleback (Gasterosteus aculeatus) are adapted to alternative trophic niches (bottom browsing versus open water planktivory, respectively) and reduced feeding performance of hybrids is thought to have contributed to the evolution of reproductive isolation.

We tested this “hybrid-disadvantage hypothesis” by inferring growth rates from otoliths sampled from wild, free-ranging benthic, limnetic, and hybrid sticklebacks from two lakes. There were significant differences in growth rate between lakes, life-history stages, and among years (maximum P = 0.02), as well as interactions between most factors, but not between hybrid and parental species sticklebacks in most comparisons.