The size, symmetry, and color saturation of a male guppy’s ornaments forecast his resistance to parasites

Sexually selected ornaments range from highly dynamic traits to those that are fixed during development and relatively static throughout sexual maturity. Ornaments along this continuum differ in the information they provide about the qualities of potential mates, such as their parasite resistance. Dynamic ornaments enable real-time assessment of the bearer’s condition: they can reflect an individual’s current infection status, or resistance to recent infections. Static ornaments, however, are not affected by recent infection but may instead indicate an individual’s genetically-determined resistance, even in the absence of infection. Given the typically aggregated distribution of parasites among hosts, infection is unlikely to affect the ornaments of the vast majority of individuals in a population: static ornaments may therefore be the more reliable indicators of parasite resistance. To test this hypothesis, we quantified the ornaments of male guppies, Poecilia reticulata,
before expe...