Data from: Sneaker males affect fighter male body size and sexual size dimorphism in salmon

• Main Authors: Weir, Laura K., Kindsvater, Holly K., Young, Kyle A., Reynolds, John D.
• Format: Dataset
• Language: unknown
• Published: 2020
• Subjects: Life sciences; medicine and health care; Reproduction: strategies; Selection: sexual; Oncorhynchus masou; Salmo salar; Fish; sexual dimorphism; Oncorhynchus keta; Oncorhynchus gorbuscha; competition; Japan; Russia; United States of America; Canada; psy; anthro-se; Keta; Weir; Atlantic salmon; Pink salmon
• Online Access: https://doi.org/10.5061/dryad.76rd1

Large male body size is typically favored by directional sexual selection through competition for mates. However, alternative male life-history phenotypes, such as "sneakers," should decrease the strength of sexual selection acting on body size of large "fighter" males. We tested this prediction with salmon species; in southern populations, where sneakers are common, fighter males should be smaller than in northern populations, where sneakers are rare, leading to geographical clines in sexual size dimorphism (SSD). Consistent with our prediction, fighter male body size and SSD (fighter male∶female size) increase with latitude in species with sneaker males (Atlantic salmon Salmo salar and masu salmon Oncorhynchus masou) but not in species without sneakers (chum salmon Oncorhynchus keta and pink salmon Oncorhynchus gorbuscha). This is the first evidence that sneaker males affect SSD across populations and species, and it suggests that alternative male mating strategies may shape the evolution of body size. Weir et al. Anadromous body sizeAverage body sizes for male and female salmon across populationsWeir et al. Parr maturityIncidence of parr maturity in Atlantic salmon (Salmo salar) and masu salmon (Oncorhynchus masu)