Do male guppies choose a light environment that makes them more attractive to females?

In variable coloured ambient lights, the appearance of an animal’s colour pattern can vary greatly. It is currently unknown if animals can actively select a light environment that maximises the efficiency of their signal to conspecifics. Individuals that can choose an environment that increases the visibility of their signal to potential mates, but not predators, can reduce trade-offs and maximise fitness. The objective of my research project is to determine if male guppies (Poecilia reticulata) choose a light environment that enhances the conspicuousness of their colour signals to females. Male and female guppies were given the choice of four light environments to inhabit during 15-minute paired trials: blue, orange, green and ultraviolet-white (UV-white). Various aspects of male courtship behaviour and the amount of time spent in each light environment were measured to test for light environment preferences. Measurements of individual male colouration were obtained by photographing test males. Males performed sigmoid displays, but not sneak copulation behaviour, differently in the four light environments. Female location was associated with preferred display environment. Both males and females spent the most amount of time in the green environment. The shape and diversity of male colour patches was associated with display behaviour, but only when the preferred light environment was green, blue or UV-white. Males that preferred to display in blue light had a higher relative area of violet spots, a colour that best reflects blue light. There was no association between male colouration and sneak copulation behaviour. These results suggest that where males choose to display is related to a complex interaction between female location, light environment and male colouration. Factors such as predation risk and food abundance may also influence this relationship and provide interesting avenues for future research.