Do Female Fancy Guppies (Poecilia reticulata) prefer similar colored males?

Students in General Biology Lab I at the University of Colorado at Boulder (Summer 2006) observed Fancy Guppies in various tanks and derived questions they wished to test. A commonly derived questions was:

What charactristics in males do females prefer?

Students derived numerous active hypotheses to potentially explain the question. A main hypothesis was -- Color indicates environmental adaptation so females should choose males with a similar color. In this meta-analysis of student-compiled data I tested this hypothesis

To test this hypothesis, I went to 4 classrooms of General Biology Lab I during the second day of lab, and recorded all the values from student experiments. In their experiments, student groups utilized pairs of 2.5gallon tanks. In one tank, one female Fancy Guppy was present (either black or yellow). In the second tank a divider divided the tank in two equal halves. Students then attempted to control all of the variables they could so that the two halves of the male tank were the same and the female tank was also homogeneous. Students placed one yellow colored male in one side and one black colored male on the other side of the divided tank.  Students then allowed the female to see the males and recorded either the length of time the female spent on each half of the tank. Trials ran for 2.5 min. To control for uncontrolled variation between tanks, males were switched in the tank and a second trial was run. A single mean for both trials together was recorded in each experiment.

Students ran experiments utilizing 12 females and more than 30 males. The same females and males were used more than once in the experiments. Typically when a female noticed the male she would swim to the male and display. The males would respond with a display. The female would then swim off and seem to pick up food off of the gravel. In some trials females appeared to show preference for one of the two males, in other trials, females appeared to prefer a side of the tank over the males. Some females seemed to show preference toward the brighter male and some toward the less bright male. Overall the results showed that the time females spent with the similar colored fish was not significantly different than the time they spent with the different colored fish (N = 16, mean same = 87.3 sec., mean different = 62.9 sec., P _two-tail = 0.24). I did a second analysis to quickly see if the females prefered the yellow males to the black males. The results indicated that the females spent significantly more time with the yellow males (mean yellow = 100.1 sec., mean black = 50.1 sec., P _two-tail = 0..004).

These data are not consistent with the prediction that females prefer to mate with males of similar color, but indicate that females prefer to mate with more brightly colored males.