Hey, Nice Caudal Peduncle! The Effect of Caudal Peduncle Depth on Mate Selection in Male Guppies

Abstract

     Often times in nature, the males of a species can be seen flaunting a beautiful tail or a particularly spotting plumage in order to attract females, but what makes them decide to vie for one female’s attention over the other? In order to answer that question, a lab favorite in the guppy Poecilia reticulata may prove useful. While it may seem clear that the male would select the mate that gives the greatest chance to pass down his genes, it is important to understand specific factors influence that decision. After preforming background trails, the general behavior of the male guppies was identified as selecting for more reproductively fit males as opposed to females who might see less competition from other suitors. Following this, in order to further guide our research we questioned whether a decreased caudal peduncle depth would have a negative effect on reproductive fitness in female guppies and thus make males less attracted to them. By exposing several different males to two female guppy models with differing caudal peduncle depths, we were able to gather data relevant to our questions. By the conclusion of the experiment, it was found that male guppies on average gave the female model with a deeper caudal peduncle more mating attention. These findings suggest that caudal peduncle depth is an important piece in the reproductive fitness of female guppies. This has importance on two levels: Firstly, with guppies acting as a model organism, there is a greater support for the conclusion that males of various species can be choosy in selecting a mate; secondly, the results may help future researchers by providing an avenue to analyze both guppy and related fishes’ mate choice beyond the more obvious features like overall size and color.