LAUSR

When females prefer mates with rare phenotypes, sexual selection can maintain rather than deplete genetic variation. However, there is no consensus on why this widespread and frequently observed preference might evolve and persist. We examine the fitness consequences of female preference for rare male color patterns in a natural population of Trinidadian guppies, using a pedigree that spans 10 generations. We demonstrate (i) a rare male reproductive advantage, (ii) that females that mate with rare males gain an indirect fitness advantage through the mating success of their sons, and (iii) the fitness benefit that females accrue through their “sexy sons” evaporates for their grandsons as their phenotype becomes common. Counter to prevailing theory, we show that female preference can be maintained through indirect selection. Description A passing advantage Female choice plays a large role in shaping populations. Across many species, females have been shown to prefer males with traits that are rare or uncommon. How this preference is maintained over time has remained an open question. Potter et al. looked across generations in Trinidadian guppies and found that females do have a clear preference for rare males, and that they acquire a further fitness benefit through sons that also have these rare traits. Once rare traits become more common, however, this fitness benefit dissipates such that rare traits in the father eventually become common, leaving the grandsons to be less preferred. —SNV Female rainbow fish that mate with males exhibiting rare color patterns gain fitness through the reproductive success of their sons.