The effect of turbidity on female mate choice in the guppy
Environmental pollutants can increase communication costs and distort the accuracy of received information, leading to negative effects on the outcome of behavioural adjustments. In aquatic ecosystems, water turbidity shows high levels of natural variation, but human activities amplify its magnitude and extent by increasing algae and suspended solids in the water and algal growth. Here we investigated how elevated levels of water turbidity affected mating decisions made by female guppies (Poecilia reticulata). We manipulated turbidity by varying the amount of suspended solids and tested for whether female guppies modify their preference for males with more orange coloration. We found that females spent more time near males with a greater area of orange colouration in clear water, but that this preference disappeared in both the low and high turbid water treatments. Moreover, we found that female preferences were highly repeatable in clear water and high turbid water but not in low turbid water. Together, our results suggest that water turbidity impairs the ability of females to discern male colouration and affects the consistency of mate preferences. This could have consequences for the evolution of male colouration in turbid waters.