Exploring sexual selection by female choice in Guppies (Poecilia Reticulata)

Thienphu Nguyen

General Biology I Fall 2013

Salve Regina University

October 18, 2013

Professor: Dr. Chace

Abstract:

We conducted an experiment to test the sexual selection of female choice in color amongst guppies or, Poecilia Reticulata. Our hypothesis was that female guppies would tend to choose the brighter colored male guppies than the males with a dull color. We ran the experiment in one day for five trials, consisting of 30-second intervals that go on for 10 minutes for each trial. Five female guppies were changed to see which male guppy they had each preferred. Our results show that female choice in color was not evident because the five female guppies showed enough interest on both sides on the tank. So color does not justify female selection in guppies. Our results only proved that female choice of male guppies is not determined by color alone.

Introduction:

Darwin proposed natural selection because species will tend to choose mates in hopes that evolution will occur when heritable traits leads to differential success in survival and reproduction (Freeman 472). Sexual selection occurs between species because the males or females are trying to attract mates to reproduce and spread their good alleles to their offspring. Two types of sexual selection may occur: one type of selection is by female choice and the other is male-male competition (Freeman 475-477). Female choice occurs because females invest much more in their offspring than do males (Freeman 475-476: Figure 26.9). The females have the choice, but the males have the traits. If one wants their offspring to live, they must choose a male with high fitness. Male species, such as the peacock, is a great example of how female selection occurs. The male peacock has a very bright and colorful body and tail. They try to impress the duller colored females to mate with them and have offspring with good alleles. Sometimes the bigger and more elaborate the male peacock’s body is, the higher chance it will have to mate. In this study, we examined guppies (Poecilia Reticulata), both female and male to determine if sexual selection by female choice in color was evident. To do this we recorded how many times a female guppy would choose either a male guppy with a brighter physical appearance or a duller physical appearance.

Methods:

Obtaining/ Maintaining the Guppies
On September 24, 2013, in O’Hare room 144 located on Salve Regina University, a following experiment was conducted to test female guppy preference to different colored males. The guppies used in the study came from the classroom with no history of origin. Whether fish were fed or not was unknown as well. The study consisted of 7 guppies in total; 2 male guppies and 5 female guppies, and a 2.5-gallon tank. Experiment was done inside, so the temperature was at 23 degrees Celsius or room temperature.

Experiment In this experiment seven guppies were tested in total: 2 male guppies and 5 female guppies. The two male guppies differed in color. One guppy was a bright multicolored (yellow and orange) and the other one was black and dull. I should add that the brighter male guppy had a larger tail and was overall bigger in size compared to the black smaller male guppy. That could have been a factor to the results received during the trials. Five females were used and all were different in tail color and size. Female guppies generally used during the study had different colored tails rather than its whole body being different color. A 2.5-gallon tank was used to keep the guppies in while having glass dividers to divide the males and the female guppy. The female guppy was placed in the middle while the dividers kept 2 of the males separated to each side of the tank. A marker was used to draw a line to divide half the tank. The line drawn represented two sides for the male guppies. Of those two