The Ugly Guppy: Do male guppies have a preference for symmetry?

Abstract

Symmetry plays an important role in the mating process for many species. Humans subconsciously prefer mates that show a more symmetrical appearance rather than someone who does not. In addition, not only is symmetry an important factor for humans, but symmetry is also prevalent in how animals choose their potential mates as well. Many species select potential mates according to their physical outward appearance in hopes of creating an offspring with a high fitness rate. In order to test this theory, our experiment observed male guppy mating behavior in the presence of both a symmetrical and asymmetrical female guppy model. We created these female guppy models by printing them from a 3D printer and drawing symmetrical (black speckled on both sides) and asymmetrical (black speckled on one side and black stripes on the other side) features onto the models. We hypothesized that male guppies would prefer the symmetrical female guppy model compared to the asymmetrical model due to the fact that animals prefer a more symmetric mating partner. At the conclusion of our experiment, we found that ---