Data from: Color vision varies more among populations than among species of live-bearing fish from South America

Background: Sensory Bias models for the evolution of mate preference place
a great emphasis on the role of sensory system variation in mate
preferences. However, the extent to which sensory systems vary across-
versus within-species remains largely unknown. Here we assessed whether
color vision varies in natural locations where guppies (Poecilia
reticulata) and their two closest relatives, Poecilia parae and Poecilia
picta, occur in extreme sympatry and school together. All three species
base mate preferences on male coloration but differ in the colors
preferred. Results: Measuring opsin gene expression, we found that within
sympatric locations these species have similar color vision and that color
vision differed more across populations of conspecifics. In addition, all
three species differ across populations in the frequency of the same opsin
coding polymorphism that influences visual tuning. Conclusions: Together,
this shows sensory systems vary considerably across populations and
supports the possibility that sensory system variation is involved in
population divergence of mate preference.