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amplexus, amphibian, anuran, mating, reproduction, wood frog


Exploration of size-assortative mating (SAM) in animals has led to a near consensus that it arises through non-adaptive mechanisms, such as preference for large females combined with a large male advantage during intrasexual competition. Although such “apparent” SAM is well explored, whether SAM arises because of specific preferences for size-matched mates has been less thoroughly considered. We tested for “preference-based” SAM in an explosively breeding anuran (Rana sylvatica), quantifying how male and female size affected fertilization and if males preferred size-matched females. We found that size mismatch severely reduced fertilization rates. Furthermore, males preferred size-matched, not larger, females in mate choice trials. Because males that mated with much larger females fertilized fewer eggs overall than they would have with size-matched females, male preference for size-matched females is likely adaptive. Our results expand understanding of the mechanisms underlying SAM, suggesting that multiple mechanisms may simultaneously cause size-assortative mating patterns to emerge.


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Creative Commons Attribution-Noncommercial 4.0 License
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