The Effects of Poecilia Reticulata Caudal Fin Depth Size on Sexual Selection

Lydia Sander, Adriana Martinez, Kenji Sherman, Mollie Patrick, Jordan Gauss


Guppies (Poecilia Reticulata), like many other animal species, show mating preferences towards certain visual traits. Much research has been dedicated to looking at female preferences when mating, but has lagged in including male preferences. In our experiment, we looked to find how male guppies react to the increase in depth of the caudal fin of females. We hypothesize that if the female model fish caudal fin increased in depth, then the male guppy will spend more time with that model and display more sexual behaviors. The experiment was set up where two model guppies of varying caudal fin sizes, one 20 mm in length and the other 24 mm in length, were placed in a fish tank alongside a live male guppy. Using five minute trials, we sought to find which model the male guppy was more attracted to using factors such as movement of the fins and body and location of the guppy within the tank. The results of our experiment showed more attraction to the guppy model with the increased caudal fin size, therefore supporting our hypothesis. While some factors didn’t go as planned, such as some guppies being attracted to neither model, we still predict that larger caudal fin size is a preference male guppies look for when finding mates.

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