purple and orange dried beans
Activity

Are You Naturally Selected?

Introduction to evolution and Darwin's theory of natural selection

During the 18th century, talk began to center on ideas of the origin and continuity of species not based on the creation account given in the Bible. The idea of evolution that species change over time was familiar to many people, but it directly challenged organized religion.

The vast discoveries of large numbers of fossils and new species forced naturalists to consider evolution. Between 1789 and 1803, Erasmus Darwin, a physician, attempted to answer 2 questions on evolution. First, are all living things descended by transformation from a single ancestor? Second, if so, how could they be transformed? He studied anatomy, geography and earth science to come up with his theories.

In essence, he said competition and selection cause change, and overpopulation. Within two years of his death, the word “Darwinism” was used to describe his new theories. Charles Darwin, his grandson, was born five years after his death. Charles took his grandfather’s ideas and made them popular. However, the experiments needed to support evolution came when Charles sailed aboard the HMS Beagle.

Change is the fundamental mechanism of natural selection. Modifications in the environment are essential for species to change. Darwin believed that all species struggle to survive, environmental conditions change over time, species change through modification, the better modifications survive, and evolution is the process of natural selection.

Materials

Procedure

Natural Selection, the Lab (movie, later)

Part 1

  1. Count out 1,000 of each bean and place them into separate cups.
  2. As a predator, you will use a knife, fork and spoon to capture your prey.
  3. Mix the beans together in a box.
  4. The rules are as follows:
    • Each predator will use one utensil only.
    • Beans must be picked up one at a time and collected in the paper cups.
    • Each predator will count the number of beans that he or she captured and report that answer to the rest of the group.
    • You will have 5 minutes to pick up as much prey as you can.

Data Table 1: First Generation

 RedWhiteGreenLima
Knife    
Fork    
Spoon    
  1. Total each:Counting legumes
  2. Total all:

Predator Efficiency for:

Predator efficiency = single predator/total predator x 300

Part 2

  1. Write down the total number of prey remaining from the first generation.
    • Red beans:_______
    • White beans:_______
    • Green peas:__________
    • Lima beans:_________
  2. Repeat Part 1, using the remaining beans in the box.

Data Table 2: Second Generation

 RedWhiteGreenLima
Knife    
Fork    
Spoon    
  1. Total each:
  2. Total all:

Predator Efficiency for:

Predator efficiency = single predator/total predator x 300

  1. Write down the total number of prey remaining from the first generation.
    • Red beans:_______
    • White beans:_______
    • Green peas:__________
    • Lima beans:_________
  2. Repeat Part 1, using the remaining beans in the box.

Part 3

Data Table 3: Third Generation

 RedWhiteGreenLima
Knife    
Fork    
Spoon    
  1. Total each:
  2. Total all:

Predator Efficiency for:

Predator efficiency = single predator/total predator x 300

  1. Write down the total number of prey remaining from the first generation.
    • Red beans:_______
    • White beans:_______
    • Green peas:__________
    • Lima beans:_________
  2. Repeat Part 1, using the remaining beans in the box.

Questions:

  1. Which predator (knife, fork, and spoon) was the most successful in obtaining prey? Why do you think so?
  2. Which prey was the most successful at escaping the predator? Why do you think so?
  3. Which prey was picked up the most often, or least successful in escaping? Why do you think so?
  4. In which generation were the numbers of successful and unsuccessful groups changing the fastest? Why do you think so?
  5. What do these results indicate about environmental influences on predator-prey evolution?
  6. What do you think would be the ultimate fate, given enough generations, of these predators and prey?
  7. What contributions did Erasmus Darwin make to the theory of evolution?
  8. Describe the theory of natural selection as refined by Charles Darwin.
  9. What does “survival of the fittest” mean to you?
  10. How does number 9 apply to human populations, or does it?

NGSS Standards:

LS2.C: Ecosystem Dynamics, Functioning, and Resilience 

LS4.A: Evidence of Common Ancestry and Diversity 

 LS4.B: Natural Selection 

 LS4.C: Adaptation 

LS4.D: Biodiversity and Humans 

The performance expectations in LS4: 

By aroth

Return to Accessible Science main page.

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