Summer Research Program for Science Teachers
Humanities Preparatory High School
August 2005
Sexual Selection in the Animal Kingdom
Grade Level:
Introduction:
Natural selection is the mechanism driving evolution most often discussed in introductory biology classes. There is an abundance of interesting sexual and offspring rearing behaviors in the animal kingdom however, and it provides teachers with a rich springboard from which to discuss evolution through sexual selection. It enriches students’ understanding of how evolution can happen and the different forms which adaptations take. When talking about humans, social context and gender roles can lead to interesting discussion. Gender roles during the time of Darwin were much different than they are today, and may have made it extremely difficult for Darwin and his contemporaries to accept the idea of sexual selection.
Aim:
Time:
Depending on how much work is done by students outside of class, this may take two days to a week.
Teacher Preparation:
Preparation time is minimal. Teacher should have DVD and photocopies of readings ready for students. May or may not utilize computers.
Day 1
20 minutes
Put students into groups of 3 or 4. Try to mix genders. On a sheet of paper, have students draw a line down the middle and write male on one side, and female on the other. Ask students to spend 5-10 minutes writing out things that each gender does in order to attract a mate. At the end, ask each group to read off what they have. Put checks next to ideas each time they are repeated. There should be overlap. Start asking students questions to start getting them to think in terms of biology class and sexual selection. Possible questions:
10 minutes
Explain to students that reproduction is necessary for a species to survive, so each develops its own sexual and child rearing behaviors that maximize reproductive output. Many species also have very specific physical traits that advertise their genetic fitness. If animals with these physical traits and these behaviors reproduce more successfully than their counterparts, this can drive the evolution of a species. Ask if anyone can think of a physical trait in the animal kingdom that looks like an advertisement of fitness, even if it may make them more obvious to predators. Students can think of natural selection as individual survival (Darwin after all refers to it as “survival of the fittest”), and sexual selection of survival of the offspring. This may be a good place to go over natural selection.
10 minutes
In order to reiterate the idea that reproductive strategies vary wildly within the animal kingdom, and that humans are unique in our own behaviors, pass excerpts from Dr. Tatiana’s Sex Advice to all Creation, by Olivia Judson. The book is a collection of letters written by animals of different species into “Dr. Tatiana”, asking for explanations to their particular sexual behaviors. Animals’ letters are short enough for students to read in a couple of minutes and humorous. Do not hand out responses. Each student can get a different letter. Ask for about 3-5 volunteers to read their letters.
5 minutes
Homework: Students should write a page comparing and contrasting natural selection with sexual selection.
Day 2
Have students work in the same groups as the previous class. Hand out envelopes with readings from the following website:
http://faculty.vassar.edu/suter/1websites/bejohns/mateselection/index.htm
This explains a number of extremely interesting mating strategies.
It will be impossible for each student to read all of the information, so you may want to have all 8 strategies in each group. In this case, each student will be responsible for sharing back to the group. Notes from each student should be collected. In the other case, each group can be responsible for one strategy and report back to the entire class.
By the end of the class, each student should pick one animal from the readings, which they would like to focus on.
Homework: Students must write a letter to a sex doctor, by their animal. Refer back to Dr. Tatiana’s Sex Advice to All Creation. It should be written as the animal, and describing a problem or confusion over why something is happening. They should address it to a sex doctor, and should be creative in their descriptions. This should only take about one paragraph.
Students should also go online to investigate their animals further. A worksheet with guiding questions and letter rubric is attached.
Day 3
Go over how to use Microsoft Publisher. The newsletter format would be the best format for this. Students can begin to put their letters into publisher. They may also begin to write their response. Responses should be finished for homework. Students should also include an explanation of their animals, to put the letter in context. When the assignment is completed, student work can be collected into one publisher file and printed. Letters are often educational but funny and creative.
Resources:
Johns, Benjamin. “Mate Selection as an Agent of Natural Selection.” Robert B. Sutter,
PhD. Vassar College. August 10, 2005.
http://faculty.vassar.edu/suter/1websites/bejohns/mateselection/index.htm
Judson, Olivia. Dr. Tatiana’s Sex Advice to all Creation. New York: Metropolitan
Books, 2002.
“Why Sex?” Evolution: A Journey Into Where We’re from and Where We’re Going.
Prod. Jill Shinefield and Gail Willumsen. WGBH. NOVA, New York.
September 24-27, 2001.
Name: ___________________________________________________________
OK, now it’s time for you to find out a little more about your animal. Use the internet to conduct some research. Also, print out a picture of your animal.
What is your animal? Mammal? Insect? Bird? Fish?
What is the habitat in which your animal lives? Describe it in detail. For example, is it by water, in the forest, desert, are there many predators? What resources are available? What is the climate? How might these things affect its reproductive strategies? There may also be information on this in the readings from Vassar.
What does your animal eat?
What is the life of your animal like? Lifespan?
Any other interesting things you find out about your animal…
Letter Rubric
|
|
Needs Improvement |
Adequate |
Excellent |
|
Format |
Many grammatical and spelling mistakes. Could be better organized. No use of paragraphs to distinguish ideas. |
Some grammatical mistakes. Fairly well organized. |
Few to no grammatical or spelling mistakes. Ideas are well organized into paragraphs. Concepts are clearly explained. |
|
Letter Content |
The problem that the animal is experiencing is laid out. |
The problem that the animal is experiencing is clearly laid out, with connections made to reproduction and other aspects of the animal’s life. |
The problem that the animal is experiencing is clearly laid out in detail, with connections made to reproduction and other aspects of the animal’s life. |
|
Response Content |
Response is given that indicates the behavior is a reproductive strategy. |
Response is given that indicates how the behavior is a reproductive strategy. |
Response is given that indicates how the behavior is a reproductive strategy, why this behavior developed in response to the environment and makes the connection with evolution (sexual selection). |
|
Outside explanation content |
None |
Some explanation of the animal’s habitat, food, competition. |
Explanation of animal’s habitat, food, competition, other adaptations and how this may connect with its sexual behavior. |
|
Picture |
Picture included |
Detailed picture included, care taken to accurately represent. |
Picture of animal engaged in their “problem” behavior. |
Standards: