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Forces of Evolution

Explains factors that cause allele frequencies to change.

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Life Among The Rapids

Life Among The Rapids

Congo River rapids between Ubundu and Kisangani. The Congo River is the deepest river in the world. Image courtesy of Terese Hart

How Deep Is It?

Have you ever watched a river flow? Depending on the river, it can be a bit like watching grass grow, which is to say... boring. But, if you find the right place on the right river, they can be pretty amazing, and you never know what's going to come down or out of the river. If you are even more adventurous, you can take a whitewater rafting trip and feel the character and power of a river. Now, that's an experience that can make you think. Researchers working on rivers put a lot of thought into what it's like to live in a river and they are finding some rivers are great places to study how species change.

No Duh's and Head Scratchers

If you need help scratching a mental itch, use the resources below:

  1. How does the complexity of the lower Congo River create opportunities for speciation? Do you think all rivers have this sort of complexity? Why or why not?
  2. How does the morphological diversity of fish in the lower Congo compare to the genetic diversity? Do you think this situation is common or rare around the world? Explain your thinking fully and use specific examples where possible.
  3. Why do researchers believe they are seeing evolution in action in the lower Congo? Do you agree with this interpretation? Why or why not? Can you think of another explanation for what researchers are finding?
  4. How do you think species diversity in the lower Congo would be affected if the river was dammed? Explain your thinking as fully as possible. Do you think effects would vary on different sides of the dam? Why or why not? What information would you need to gather to test your hypothesis?


Congo River between Kinshasa and Lukolela, Democratic Republic of Congo. Image courtesy of Ollivier Girard for CIFOR

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