Guppy Girth: The Influence of Female Size on the Mating Selections of Male Poecilia reticulata

Abstract

Sexual selection is a major determinant of the evolution, speciation, and fate of a species. The composition of species today is largely due to sexual selection of organisms, which can be influenced by numerous characteristics and practices such as size, mating behaviors, coloration, and more. These characteristics that affect mate selection are true for many fish species, including guppies. This experiment investigated the influence of female guppy size on the mating selections of male guppies. We hypothesized that male guppies will display stronger preference to female guppies as their size increases. This hypothesis was proposed based off the prior findings of the Center for the Study of Sexual Selection in Fishes (CS³F) suggesting male guppies displayed higher attraction towards larger females. Our hypothesis was investigated through the use of an online database consisting of trials testing our parameters of investigation on male guppy mate selection. This database allowed us to observe and average the amount of time male guppies displayed courtship behavior towards each model size of female guppy. The models tested were “small” and “large” against the “control” sized female guppy model. Our hypothesis was not supported after quantifying that male guppies spent a shorter average amount of time displaying courtship behavior towards the “large” followed by the “control” and “small” female guppies in increasing time the male guppy spent respectively and these amounts of time showed no significant difference according to a Mann-Whitney U test resulting in p>0.05. These results coincide with the observations of experiments testing similar hypotheses and will provide important understanding of how characteristics can affect the sexual selection and evolution of guppies and fish.