Title: Natural Selection
Principle(s) Investigated: Natural Selection - Survival of the Fittest
Standards : Past in the appropriate California content standards.
California standards:
7th Grade Science Content Standards:
9th - 12th Grade Biology/Life Sciences Content Standards:
Materials: newspaper full length, newspaper, white, and orange (or any other color than newspaper) cut-outs with sides 1cm, times-watch, students as birds use thumb and index finger of non-writing hand.
Procedure: Give a detailed explanation of the procedure and include diagrams if possible.
Click here for graph paper.
Student prior knowledge: What prior concepts do students need to understand this activity?
Variations exist within any populations: individuals in a certain population have variations.
Explanation: Give a thorough explanation of the experiment or demonstration. Your explanation should be written to give your fellow teachers a solid understanding and include greater detail than what you might provide for your secondary students. Make certain to include equations whenever pertinent.
A population of “insects” is given to students. Within the population students should notice variation or several different colored “insects.” The camouflaged insects resemble the environment (newspaper) and the un-camouflaged insects are different colors than the environment. Biologists consider natural selection to be the mechanism of evolutionary change and the process responsible for the diversity of life on earth. In this investigation, students will model the process of natural selection for one organism. The students will construct a population graph for each of the two colors of insects. The graphs should include a key. The independent variable is number of generations. The dependent variable is the insects (camouflaged/un-camouflaged) to understand that the independent variable causes a change in dependent variable. Usually, the camouflaged insects survive and reproduce in the next generation. This is “survival of the fittest.” The insects happen to have the trait to survive (blended with the environment) and reproduce. The most adapted insect is the “fittest” one to survive and pass-on the heritable trait to the next generation.
Questions & Answers: Give three thought-provoking questions and provide detailed answers.
1. How would you describe the principles of natural selection?
2. Are evolution and survival of the fittest the same thing?
They are connected to each other but nit the same thing. Evolution means change over time or "descent with modification." It is a change in gene frequency over time. For example, the study of fossil records, comparative anatomy, embryology and biochemistry, and genetics provide evidences of evolution. Whereas, survival of the fittest refers to the mechanism - natural selection, that brings about change.
3. How could natural selection work against the survival of an organism?
Natural selection is not the strongest or the smartest to survive and reproduce. The organism happens to have the trait to survive within the population. For example, the male peacock elaborates colorful and beautiful tails to attract mate and sexually reproduce. However, this heritable structural trait makes the male peacock more visible for the predators to prey on. The male peacock happens to have the trait to reproduce and pass on his genes to the next generation in which natural selection selected for this trait. At the same time, the male peacock is more visible and likely to be attacked by predators.
Applications to Everyday Life: Explain (don't just list) three instances where this principle can be used to explain other phenomenon.
One example of evolution and natural selection is the comparison of DNA. Comparisons of DNA nitrogen based sequences show that chimpanzees are more closely related to humans than to gorillas or other apes.
Another example is rapid evolution 1. The reaction of bacteria to penicillin often results in rapid evolutionary change. 2. When penicillin is added to bacteria in a culture dish, a clear zone forms indicating death of the bacteria in that zone. 3. Those few bacteria with a gene for penicillin resistance will survive and go on to reproduce (thus, the group of bacteria has evolved). 4. The organisms that continue to live and reproduce after the change in the environment are adapted to the new environment.
Photographs: Include a photograph of you or students performing the experiment/demonstration, and a close-up, easy to interpret photograph of the activity --these can be included later.
Videos: Include links to videos posted on the web that relate to your activity. These can be videos you have made or ones others have made.