Week 3 - Sept 17 & 18
Matechoice w/ Background Color Interference



The purpose of the today's lab is to determine the effect of the immediate environment on mate choice by female guppies. There are three overlapping theories to explain the evolution of mate choice, "the Direct Benefit Hypothesis", "the Good Genes Hypothesis", the "Runaway Selection Hypothesis" (also known as "the sexy sons hypothesis"). There are actually more than three, but these are the main three. If you do not remember them from introductory biology you will want to review them before coming to lab. In Essential Animal Behavior, read pg 169 - 177, or refer to Alcock for a more rigorous explanation.

In 1989 Long and Houde demonstrated that female guppies prefer orange. The evolutionary reason for this preference is still debated. Rodd et al., 2001 provides a rigorous experimental study that suggest this signal evolved as a sensory trap. Morell 2002 provides a brief summary of that rigorous study (which you might want to read before coming to lab). Dugatkin and Godin_1998 provides a genearl overview of guppy mate choice.

During lab you will become familiar with measuring matechoice preference.
You will also learn how to use ImageJ, freely available software, that allows for complex image analysis.
We will use this software to quantify the amount of orange and blue on our guppies.

For additional ideas for independent projects I suggest reading
Gross et al, 2007 which demonstrates a side preference for male display.
Alexander And Breeden 2004 demonstrates how mate choice could play a role in maintaining species boundaries.
More detailed suggestions are provided at the end of the handout.


There is no write up due for this lab.
However, in addition to a clear record of what you did in lab today, your lab notebook conclusions should include:

  1. A simple concluding statement that evaluates your results in light of the alternate hypotheses that were proposed to explain the evolution of female preference for orange color in male guppies.
  2. There should be evidence in your lab notebook of statistical tests that were run, and the p-values obtained, which led you to this conclusion.
  3. An additional hypothesis that can be tested with the data collected today, as well as the graphs, and statistical tests associated with that hypothesis.
  4. A simple concluding statement that evaluates your results in light of this additional hypothesis.

Aspects of this experiment have been abbreviated in order to fit within the 4 hour lab period and adjustments have been made to the protocol in order to allow 18 students to simultaneously work efficiently. You will be asked to consider how you would run the experiment differently if it were your own independent research.