Guppies Lab Report

Do Predators Effect the Color Patterns of Guppies?

This report is on a virtual experiment based on the real-life experiment accomplished by John Endler and David Reznick of the University of California. The goal is attempting to determine whether or not the level of predation effect’s the color patterns of guppies.

Why do populations of guppies in the same stream separated by waterfalls of about five feet have different color patterns? Humans have asked this question since someone first noticed the difference between pools of fish from the same stream. Endler and Reznick designed an experiment to discover a reason behind guppies different color patterns. They chose to focus on two different predators, the Crenicichla alta a high level predator, and the Rivulus hartii a low level predator. The experiment is divided into two parts. A greenhouse experiment and field experiment

Ponds with a high number of predators, the black spots should increase while the blue and iridescent spots might stay the same or decrease. However, they should not disappear altogether because of sexual selection. If the gravel color was changed to blue I would expect to see the amount of blue spots increase while the number of black spots should decrease slightly or stay about the same. Replacing the gravel with red gravel should result in an equal reduction of all spot colors with a possible increase in blue and iridescent spots due to sexual selection. Yellow gravel should result in an unequal reduction of blue and black spots with a slightly greater loss of black spots. There should be an increase of iridescent spots. The blue spots still should not disappear completely because of sexual selection. Over multiple generations black spots should reduce when gravel is replaced with any of the primary