Male Guppy Sexual Selection Preferences Based on Size of Female 3D Models

Abstract

Guppies, or Poecilia reticulata, have unique mating techniques that can help attract the opposite sex. Male guppies try to impress the female guppies by the sigmoid movement, gonopodial swing move, and the fin spread. We wanted to determine to what extent the characteristic of size differentiation affected sexual selection of male guppies. We hypothesized that the male guppy will be more attracted to the larger model guppy because it has larger surface area and is easier to see. To test this hypothesis, we obtained several 3D printed “female guppies” (the models lacked the pectoral fin that is recognizable by male guppies) that differentiated in color and size. Two 3D printed guppies were put into opposite sides of the tank, and time was measured as to which 3D printed guppy was the most attractive to the live male guppy based on how long the guppy spent near each model and how many times the male guppy displayed a mating behavior. The live male guppy tended to be more attracted to the larger decoy that was the same color as the control. We also tested a large orange female compared to a small orange female. The males tended to be more attracted to the smaller orange guppy when both models were orange, despite our hypothesis. During the other trials, the guppy spent more time around the larger of the two models. Based on these results, this means that male guppies mate based on size of the female guppies. This could be because they are easier for the male to see.