Insect Adaptations (Draft)

Insect Adaptations (draft)

(Simulating natural selection and evolution in a moth population)

State Standards

Grade 5, Standard 3.0 Life Science: The students will use scientific skills and processes to explain the dynamic nature of living things, their interactions, and the results from the interactions that occur over time.

A. Diversity of Life

1. Explain the idea that in any particular environment some kinds of plants and animals survive well, some less well, and some cannot survive at all.

a. Identify and describe features and behaviors of some of the plants and animals living in a familiar environment and explain ways that these organisms are well suited to their environment.

b. Based on information about the features and behaviors of animals and plants from very different environments, describe reasons that they might not survive if their environment changed or if they were moved from one environment to another.

d. Research the kind of environment needed by the Maryland blue crab, the black-eyed Susan, or another Maryland native organism.

e. Explain that the survival of individual organisms and entire populations can be affected by sudden (flood, tsunami) or slow (global warming, air pollution) changes in the environment.

Objectives

Students will explain how insect populations change over time as the environment changes and identify a variety of insect survival adaptations. They will simulate natural selection and evolution of camouflage by creating a population of paper moths and subjecting it to predation over several generations.

Required Materials

• copies of the page at the end of the lesson that contains moth outlines (each student will need approximately four or five moth outlines)
• a variety of pencils, pens, colored pencils, and markers
• scissors, one per student
• masking tape
• at least two different materials, square, approximately 1.5 meters per side) to represent two different environments(recommended: environment 1—tape together several sheets of black and white newspaper that has some color photos/comics/adson it; environment 2—use a piece of fabric or wrapping paper that has a floral, geometric, or other print)
• if you aren’t permitted to use masking tape to attach your environments to the wall, you will need another type of fastener such as poster putty or push pins

Time Required

approximately one hour (length can be adjusted by adding or removing generations in the simulation)

Background Information

This simulation is an excellent experiential learning activity that helps students understand the concepts of natural selection and evolution of a population so that it becomes adapted by means of camouflage to its environment. You may want to hide the objectives of the activity from the class so that students must figure out the concepts on their own as they experience the activity. Here is a generic objective: Observe how a moth population changes over time as it experiences predation.

Organisms are members of the same species if they can breed with each other and produce offspring (babies) that can also reproduce. A population is a group of organisms from one species that live in a certain geographic area. Within a population, there is genetic variation. Individuals are usually slightly genetically different from one other. For example, the students in a classroom are all people; however, they all appear and behave slightly differently from one another because the population in the classroom has genetic variation within it.

Because organisms are genetically different from one another, some individuals have traits that help them survive better, these individuals are said to have adaptations for survival. Some individuals are well-adapted for certain conditions, but other individuals are well-adapted for other conditions.Natural selection is the differential survival and reproduction of some organisms over others in a population because some organisms are better adapted to survive certain environmental conditions.If similar environmental conditions arise over several generations, the population will eventually evolve to consist of individuals that are better adapted to survive the environmental conditions. Evolution is the genetic change in a population over successive generations. A population that evolves to become better adapted to its environment may also be forced to evolve in a different way if environmental conditions change.

Engagement

Read this statement: “Today we are going to observe how a population of moths changes over time as it experiences predation (as the moths are eaten by predators).” Remind students that insects are the most widespread and diverse class of organisms on Earth. Ask them to name several kinds of insects and suggest reasons why insects are so successful. Answers may include ability to fly and disperse, ability to live in many different environments, rapid reproduction, production of large numbers of offspring, ability to eat a variety of different foods, ability to become dormant in winter, and camouflage (the subject of this activity).

Discuss ideas. Next, mention moths and ask students what they know about moths. Some may mention that moths are related to butterflies, many moths are active at night, some moths are pests and eat crop plants, some moths are beneficial and pollinate crop plants, moths like to fly toward light, etc. Show the class several photographs of moths that demonstrate a diversity of body and coloration styles. Tell students that they will be designing their own moths and observing what happens to the population when a predator eats most of the moths.

Exploration

Select one student to be the “crow”, a predator. This person will not design a moth; instead, he or she will help the teacher prepare a particular background environment (newspaper, fabric, etc.) to be hung on the wall using masking tape. This must be done out of the view of the other students.

Students may work at lab stations or at their desks. Give each student a strip of paper containing simple outlines of a moth. Emphasize that these moths are all members of a population of paper moths. They are similar in size and shape, but this population has a lot of color variation. Allow students approximately five minutes to design and cut out a moth and put a small loop of masking tape on the back of the moth.

After all moths have been designed, explain that this population of paper moths has experienced habitat destruction in its home area because a construction company cut down the trees and fields where the moths used to live. The moths are moving to a new area. Have the predator help you tape the new environment background to the wall or the white board. Ask the crow to turn his or her back and wait as the rest of the students tape their Generation 1 moths somewhere in the new environment. When everyone has returned to his or her seat, the predator will turn around, grab the first moth in view, grab it, and turn back around. He or she will give the moth to the teacher, and the teacher will tape it to the wall to show what color pattern was eaten first. The predation will continue until only six or eight moths remain. The “dead” moths will be taped to the wall in a line from first eaten to last eaten. The surviving moths will be taped to the wall as a group. Students will be reminded that these moths survived and that they will be the ones to reproduce and pass on their traits.

Repeat the moth design and predation process for Generation 2. You may choose a different predator this time. Remind students to look carefully at the colors and patterns of moths that survived in Generation 1. The moths in generation 2 will begin to resemble the surviving moths from Generation 1 and/or the colors and patterns in the background environment. The moths remaining at the end of Generation 2 will already appear more closely adapted to the environment. (Some students will still insist on using their original colors instead of relying on the colors of the surviving moths, but you can justify the rare appearance of the “selected against” colors by saying that some genes are hidden (recessive) and can show up in later generations.)

Repeat for Generations 3, 4, or 5 depending on the amount of time you have available for the activity. By this point, the population will very closely resemble the environment. After students have designed their last set of moths, tell them that another construction company destroyed their current habitat and that the moths are moving again to a new area. Change the environment to something dramatically different, and view the effects of predation on the population again.

Explanation

Ask students to describe what they observed during the simulation. Guide the discussion to the fact that the population had genetic variation with regard to color and pattern. When the moths moved to a new environment, some of them were better adapted(in this case camouflage, but adaptation can happen based on other traits and behaviors too) to blend in. Camouflage occurs when organisms possess traits that allow them to blend in with their environments. The moths that were less adapted were more visible to the crow, and the crow saw them first and ate them. Those that were more adapted were less visible to the crow and were more likely to survive. Natural selection is the process by which organisms that are better adapted to their environment survive and reproduce. Future generations tend to possess the traits of their parents, and the genetic makeup of a population can change over time. Evolution is the change in the genetic makeup of a population over time as a result of natural selection. The moth population in this simulation evolved to become better adapted to its environment, but when the moths moved to a different environment at the end of the simulation they were not as well adapted to the new environment.

Extension

Ask students higher-level thinking questions such as these:

1. If the moths had stayed in the first environment for many, many years, what might the population begin to look like?

Answers will relate to the population become highly adapted so that individual moths blend seamlessly with the background. Some students might suggest other adaptations such as the ability of moths to live in crevices or under leaves, adaptations that will help them survive without needing adaptive colors.

2. If the moths moved to and stayed in the final environment we used, how might the population be different from the one we discussed in question 1?

Students will probably conclude that similar processes will take place that lead the population to become better adapted to the new environment. The final result might be a very different-looking population compared to the original population.

3. If the moths are undergoing natural selection due to changing environmental conditions, how might the crow populations be evolving?

Possible answers include evolution of keen eyesight or sense of smell that helps crows find camouflaged moths, ability to migrate and follow moth populations as they move to new areas, ability to eat more than just one species of moth to get enough food, etc.

4. What other examples of camouflage can you think of?

Students might suggest a variety of adaptations including walking stick insects that resemble tree bark, chameleons that change color to blend with their environments, flounder fish that cover themselves with sediment, etc.

5. Besides camouflage, what other kinds of adaptations can you think of?

Answers may include ability to fly to travel to food sources and escape predators, noxious chemicals in plants and animals that make them less appealing to predators, shells and other protective coverings, development of plant seeds that float in the wind and increase seed dispersal, etc.

Simulation extension activity

Let students suggest a variation on the simulation. Ideas might include providing a variety of environments at the same time for the moths to colonize, allowing the moths to use new traits such as hiding in crevices, etc. Repeat the simulation, and observe/discuss the results.

Research extension activity

Allow students or student groups to select a certain species of animal or plant and research physical traits and behaviors that allow it to survive in its environment. Students may then share their findings with others. The class can create a comprehensive list of adaptive traits and behaviors that help organisms survive various conditions.

Evaluation

A written evaluation may be assigned. Ask students to write a description of what they observed during the simulation and explain it using the terms genetic variation, adaptation, camouflage, natural selection, and evolution.

You may also carry out informal evaluation as you ask questions during the class discussion and evaluate students’ answers for correct understanding of concepts.

Another possible evaluation is to have students complete the research extension activity described above and evaluate it for accuracy and completeness.

Career Connections

ecologist – a biologist who studies the interactions of organisms within populations of the same and different species and tries to identify how organisms help and/or hurt each other

evolutionary biologist – a biologist who studies the changes of populations over time. This biologist might observe wild or captive populations over many generations and look for changes or set up experiments that help determine how changes in the environment can affect the survival of organisms

integrated pest management specialist – an expert who looks for ways to control pests other than just by using insecticides. These specialists might research which kinds of predator insects could be released in an agricultural area to help eat pest organisms that are damaging crops grown by people for food.

veterinary researchers – these researchers know that using the same flea or tick control chemicals on dogs or cats over many generations will eventually result in a population that is resistant to the chemicals. As a result, researchers study a variety of chemicals and related products that can be used to effectively control flea and tick populations.

agricultural specialists – scientists who know that many insects are helpful to people because they pollinate crops that people raise for food. These scientists sometimes study which insect species are the most helpful with regard to pollinating food crops. They develop techniques to attract pollinator species to certain areas where food is grown.