Correlated Evolution of Female Mating Preferences and Male Color Patterns in the Guppy Poecilia reticulata

Sexual selection may explain why secondary sexual traits of males are so strongly developed in some species that they seem maladaptive. Female mate choice appears to favor the evolution of conspicuous color patterns in male guppies (Poecilia reticulata) from Trinidad, but color patterns vary strikingly among populations. According to most theory, correlated evolution of female mating preferences and preferred male traits within populations could promote this kind of divergence between populations. But mating preferences could also constrain the evolution of male traits. In some guppy populations, females discriminate among males based on variation in the extent of orange pigment in male color patterns, and populations differ significantly in the degree offemale preferences for orange area. In a comparison ofseven populations, the degree offemale preference based on orange is correlated with the population average orange area. Thus male traits and female preferences appear to be evolving in parallel.