Modelling Finch Feeding to Teach Evolution

I've struggled to teach evolution. Not in any ideological way, but as as science teacher, I've found that I've merely paid it "lip service" with some flimsy examples. I have a host of fossil replicas that suggest change over time, but the agent of change is subtle and change very slow over time.

Teaching evolution is definitely in my teaching standards: 
  1. The diversity and changing of life forms over many generations is the result of natural selection, in which organisms with adaptive traits survive, reproduce, and pass those traits to offspring. 
  2. The life processes of organisms are affected by their interactions with each other and their environment, and may be altered by human manipulation.
I've taught evolution in the past by using x rays to compare similar skeletal structures, compare DNA similarities of related species and study the work of Gregor Mendel and Charles Darwin, especially his finches. Despite all of this, I felt there was gaps in the understanding. For example, I wanted to better model the concept of adaptive traits and how subtle variations in populations is a slow catalyst for them to evolve. I wanted students to "see" evolution in action, and I wanted to create an activity that showed:
  1. How small mutations of living things create similar living things
  2. How these new species move into new environments and utilize new food sources
  3. How new traits can be adaptive or non-adaptive
  4. Data that students could collect that shows a correlation between all of the above
I've done an activity over the years called "observing evolution" but feel that I've really polished this this year with my collegue Brett MacRury, a high school biology teacher. I won't lie to you; the activity is complicated. But, my goal is to make this complexity visible and distinguishable. I've decided to video tape some segments of the activity in action, but essentially, students act the role as "scientists" and study the "living things" (students playing the part of finches) in an environment. They collect data on their choice of habitat and food acquisition frequency.


Lesson: Observing Evolution

Warm Up
Take a virtual trip aboard the Beagle with Charles Darwin!
Share some of Darwin's observations on a Google Doc

Overview
Tell students that they are Charles Darwin. They've just arrived at the Galapagos Island and they are going to study the finches that live there. They will be collecting data on what type of finches live there, what they eat and look for trends and patterns in data that are collected and observed.

Materials
  • Different color shirts for each finch (4 different colors with 3 of each color) 12 total
  • 4 large pails: 1 at each table. Have each pail labelled as a specific island of the Galapagos such as Santa Cruz, Isabella, Baltra, and San Cristobal.
  • A variety of implements to be the different beaks, (small spoon knife, poker, fork, tweezers)
  • A number of items for food (Sequins, styrofoam balls, marbles)
  • A food collection cup (Best if it's a necklace hung around the neck)
  • Clipboards for student scientists

Introducing the Activity

Tell the students that you will be observing a species of finch. Have a volunteer be the first 'finch'. This first generation of finch will try to get as much food as they can in 30 seconds. Afterwards, the finch will tell us how many food items that they collected and what type of food that they ate. If they gather and eat enough food, they reproduce. As scientists, note which island that they did their feeding at. Collect data on a simple "Google Spreadsheet" and graph and look for quick trends between generations.Google Spreadsheet is a great tool, for if you have some data that is rapidly changing, you can instantly create a new chart to show these changes.



After generation 1, add another member to the same species, rinse and repeat. You may also choose integrate the concept of "carrying capacity" of an island. Eventually, introduce a new species with a new implement that is the mutation; when released, this new species will find a food source at another island and find a underutilized food source. Some living things (like those that

Debriefing
The purpose of this activity is to see the connections that Darwin did. The reality of Darwin's work was that he formulated his theory for years after making observations and collecting specimens on the island. Eventually, Alfred Wallace contacted him with a similar theory and Darwin postulated the concept of "Natural Selection", namely that adaptive traits make it easier for certain organisms to survive which have a better chance of perpetuating their species.






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