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Page history last edited by gerryc 12 years, 5 months ago

O9. Not all offspring will survive to reproduce.


Student Outcome:O9.1

Understand that some genetically controlled characteristics increase the chances of survival and reproduction.


Theory of Natural Selection


  1. This unbounded population growth resembles a simple geometric series (2-4-8-16-32-64..) and quickly reaches infinity.
  2. As a consequence, there is a "struggle" (metaphorically) to survive and reproduce, in which only a few individuals succeed in leaving progeny.
  3. Organisms show variation in characters that influence their success in this struggle for existence. Individuals within a population vary from one another in many traits. (Animal behavioralists making long-term studies of chimps or elephants soon recognize every individual by its size, coloration, and distinctive markings.)
  4. Offspring tend to resemble parents, including in characters that influence success in the struggle to survive and reproduce.
  5. Parents possessing certain traits that enable them to survive and reproduce will contribute disproportionately to the offspring that make up the next generation.


To the extent that offspring resemble their parents, the population in the next generation will consist of a higher proportion of individuals that possess whatever adaptation enabled their parents to survive and reproduce.


The well-known example of camouflage coloration in an insect makes for a very powerful, logical argument for adaptation by natural selection. Development of such coloration, which differs according to the insect's environment, requires variation. The variation must influence survival and reproduction (fitness), and it must be inherited.


Go here for a peppered moth simulation. Play the simulation for at least two minutes and make a note of what happens to the populations of peppered moths

(BTW you will need to go to the bottom left hand corner of the menu frame to start the simulation)


Here is another simulation - this time with beetles - read the instructions first!


Although not directly on the topic, these videos show a simulation of natural selection in computer animations.

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Very simple explanation of how natural selection can lead to new species


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Here is how the eye may have evolved - using computer graphics.


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This version shows how eye evolution may have occured using models:


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Here is an idea for introducing evolution and natural selection.


This video is about human evolution. Just for interest sake.

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Now for something completely different - some Evolution games! Go here - That's Evolution.


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