High-frequency fish: a study over colour-wavelength preference within Poecilia reticulata

Abstract

The guppy species Poecilia reticulata inhabits lakes and rivers throughout the world, making it a perfect candidate for studying the broad habits of fish.  The Center for the Study of Sexual Selection in Fish (CS³F) studies the mating habits of Poecilia reticulata, performing experiments using male guppies of this species and recording any data they find over the proximate causes of such habits in the Journal of Introductory Biology Investigations in order to determine the ultimate cause for these mating choices.  Previous experiments have shown that both samples of cichlids (another common river and stream fish) and other samples of Poecilia reticulata favour a blue colouration, both over fish with a red colouration and other fish with less blue colouration.  It has also been shown that Poecilia reticulata prefer a UV colouration.  Since the blue and UV colours have a higher wavelength than the red colour, we hypothesised that the sample fish were more drawn towards fish that have a colouration with a higher wavelength due to higher-wavelength colours being able to penetrate water better than lower-wavelength colours.

In order to study this claim, we compared data from previous experiments for our specimens’ (male Poecilia reticulata)  preference towards a true purple-model fish (high-wavelength) and a true orange-model fish (low-wavelength) compared to a warm grey-coloured model fish control and averaged both the time spent in proximity to the models and the number of significant courtship displays towards the models in order to determine which model they had a preference towards.  The specimens were shown to spend significantly more time on average within proximity of the true purple-model fish, but the specimens showed a slightly higher number of courtship displays on average towards the true orange model-fish.  Taking the time spent with each model along with the insignificant difference within the number of noted behaviours, it seems that the specimens had a preference for the true-purple model, supporting our hypothesis.  This may be due to a variable outside of colouration, such as external stimulus or a simple bias against orange colouration, further experimentation may be required in order to support our hypothesis fully.