The colour of guppies (Poecilia reticulata) evolves as a compromise between sexual selection (favouring conspicuousness) and natural selection (favouring crypsis). However, guppies live in a variety of habitats and with a variety of predators and consequently in a variety of selective environments. I investigated how habitat and predator's visual systems affect the evolution of colour. I used regressions to assess the importance of habitat features on the evolution of colour for 29 guppy populations. I then quantified the colour of guppies living in the presence and absence of two predators. The prawn predator is insensitive to orange light while the fish predator is insensitive to ultraviolet light. Habitat explained some variation in colour, but not in a consistent manner. Guppies living with the prawn were more orange and guppies living with the fish had more ultraviolet reflectance, providing evidence for the use of these aspects of colour as private signals.

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