Login processing...

Trial ends in Request Full Access Tell Your Colleague About Jove

A subscription to JoVE is required to view this content. Sign in or start your free trial.

Sexual Selection and Mate Choice
Sexual Selection and Mate Choice

Learning Objectives

At the end of this lab, students should know...

What is sexual selection?

Sexual selection is a mode of natural selection that acts on traits involved in mate choice and reproduction.

Name and describe the two types of sexual selection.

Intersexual selection is selection that occurs between the two sexes and serves to help an individual attract the opposite sex. Intrasexual selection is selection within a sex. This occurs when individuals compete against each other to acquire mates.

Under what conditions would sexually selected traits evolve largely unrestrained ("runaway selection")?

Runaway selection occurs in environments that favor survival, where resources are plentiful and predators are lacking.

What is operational sex ratio (OSR)?

Operational sex ratio is the proportion of sexually mature males to sexually mature females within a population.

Why are females generally more mate-selective?

Females invest a greater amount of energy into producing fewer eggs compared to sperm. The OSR of a population is also more often male-skewed. As a result, females are generally more selective than males.

List of Materials

  • MaterClip-on Plastic ID Holdersial
  • Paper clips
    20 /station
  • 5/8" Black Dot Stamp (optional)
    20 /station
  • Blue construction Paper (8 blue sheets, to make cards)
    1 /station
  • Pink Construction Paper (5 pink to make cards)
    1 /station
  • White paper strips (too cover the score)
    1 /station
  • Permanent Marker
    1 /station
  • Stopwatch
    1 /station

Lab Prep

  1. Determining Roles and Making Gamete Packages for Class
    • First determine the quantity of materials needed based on the class size. This activity can easily be scaled up or down. In Table 1, options are listed for 30, 20 or 10 students. Click Here to download Table 1 NOTE: You may easily create a custom number by following these simple guidelines.
      • Ensure an equal male-to-female ratio.
      • Designate the majority as average quality individuals.
      • Make the number of high- and low-quality individuals equal.
      • Ensure that there is always an even number participating in the matings - If there is an odd number of students, have one student help tally the matings each round.
    • To prepare the information badges that the students will wear, first acquire 10 clip-on plastic ID holders.
    • Using a permanent marker, number the holders one through 10 in the upper and lower right corners.
    • On the left side, write a Q in the upper corner and an A in the lower corner.
    • Next, use table one as a reference to draw dots next to the Q and A for each of the 10 quality and attractiveness value combinations.
    • Cut strips of white paper large enough to cover either the Q or A sections of half of the ID holders.
    • Put one strip of paper along with three paper clips into each male ID holder.
    • Next, prepare the strips of paper that will represent gametes. Pink and blue paper works well to represent eggs and sperm respectively, though any two distinct colors can be used. See Figure 3 for a cutting template. Click Here to download Figure 3
    • Each student playing a female in these activities should receive four strips each. With a permanent marker, number sets of four pink strips with each female individual number.
    • Each student playing a male in these activities will receive 16 strips of blue paper and one strip of white paper each. Number sets of 16 strips with each male individual's number.
    • Finally place the strips of paper into each corresponding ID holder.
    • Next, before the lab begins, establish an open mating area and a desk or group of desks as a fertilization area a little distance from the mating area where students may place paired gametes.
    • Then, place at least 20 paper clips on the desk within the fertilization area to allow students to clip paired gametes together.
    • Make sure a computer is readied with Spreadsheet 1 open as during the mating activity, the instructor or helper will keep time and record which matings occur. Click Here to download Spreadsheet 1
    • Note: The example data sheets are originally formatted for a group of 30 students. For larger or smaller groups, the formulas for average number of matings and average reproductive success will need to be modified to include the correct number of individuals.
    • Once the lab simulations are completed, you will provide the tallied class data from this class spreadsheet for the students to prepare graphs. Instead of providing the full data sheet, copy and paste the relevant data as “values only” into Spreadsheet 2 and give this to the students. Click Here to download Spreadsheet 2


JoVE Lab Lab: 31 Prep

Get cutting-edge science videos from JoVE sent straight to your inbox every month.

Waiting X
Simple Hit Counter