My AP Biology Thoughts  Unit 7 Natural Selection EPISODE TITLE: The Threespine Stickleback

Welcome to My AP Biology Thoughts podcast, our names are Beth, Gillie, and Addie and we are your hosts for Unit 7: Examples of Evolution- The Threespine Stickleback. In episode 119, we will be discussing The Threespine Stickleback and how it relates to the AP Biology Curriculum. 

Segment 1: Overview of Threespine Stickleback

The Threespine stickleback fish live in the ocean and in lakes. The fish who live in the lake have been separated from the ocean sticklebacks for thousands of generations. Although there is a difference between ocean and lake sticklebacks, all freshwater sticklebacks can vary in shape and size depending on habitat. Scientists looked into the differences between lake and ocean sticklebacks by taking 50 fish from each population and comparing them.

Segment 2: Evidence that supports Threespine Stickleback

Freshwater sticklebacks and ocean sticklebacks have a number of different physical characteristics. For example, Ocean Sticklebacks are generally much larger. They also differ in body length, spine length (and number), fin shapes, number of lateral plates (​​Genetic Science Learning Center, 2017, August). The scientists observed that the average number of lateral plates for ocean sticklebacks was 33. On the other hand, the average number of lateral plates was 5 in the lake stickleback. Additionally, Michael Bell ran an experiment where he determined just how fast this evolution was occurring. He tracked the genes of stickleback fish in lakes in Alaska and determined the speed at which evolution occurred (in just a decade) (Robert Sanders, M. R., & Sanders, R., 2021, June 21). More interesting, however, is the fact that fish evolved convergently across the globe due to similar conditions, despite being isolated for decades (Shen, H., 2012, April 04). 

Segment 3: Connection to the Course

The Threespine Stickleback demonstrates natural selection and adaptation in the environment, which directly relates to section 7.1 and 7.2. The data of how lake and ocean sticklebacks have adapted over time is a prime example of fitness. The environment of the lake and the ocean are different, and as a result, the lake stickleback has evolved to better suit this body of water. The evolution of the Threespine Sticklebacks caused by natural selection in different environments connects to 7.1 and 7.2.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
• http://creativecommons.org/licenses/by/4.0/

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