Evolution: It’s For the Birds

Evolution: It’s For the Birds
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Nature has an amazing way of adapting to its ever changing surroundings. Over time, humans, animals, and plants have evolved to best suit their environment. Collier Middle School science teacher Ms. Paige Barnett and her 8th grade science classes are studying how Galapagos finches have passed on certain favored genes to the next generation for their best rate of survival.

Using a study from evolutionary biologists Peter and Rosemary Grant, Ms. Barnett and her students learned how quickly natural selection can take place. In 1977 during a severe drought in the Galapagos Islands, seeds were scarce and many finches struggled to survive except for the finches with larger, stronger beaks who were able to open hard seeds. These birds “won” the round of natural selection and lived to pass on their bigger, stronger beaks to the next generation (a 4% increase in beak size in just 5 years!) while smaller finches with less powerful beaks died off. A few years later, the Galapagos Islands had an unusually rainy season providing an abundance of small, soft seeds causing the larger beaked finches to be unable to grasp the small seeds resulting in the finches’ evolving back the other direction.

Using cards with images of the Galapagos finches the Grants studied, Ms. Barnett and her students were able to categorize the birds based on their beak size to show the difference over time. “We were learning about Charles Darwin and my group was studying what the Galapagos finches ate, like nectar and seeds. When these food changed or weren’t available, the beaks changed. It was interesting to see how the same species of birds can be different depending on where they live and what’s available for them,” Jace B., a Middle School eighth grader. 

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