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
- 1,000 each of red beans, green peas, white beans, Lima beans
- cups
- large box or pan
- knives, spoons, forks
- timer
Procedure
Natural Selection, the Lab (movie, later)
Part 1
- Count out 1,000 of each bean and place them into separate cups.
- As a predator, you will use a knife, fork and spoon to capture your prey.
- Mix the beans together in a box.
- 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
| Red | White | Green | Lima | |
| Knife | ||||
| Fork | ||||
| Spoon |
- Total each:
- Total all:
Predator Efficiency for:
- Knife (Pk):
- Fork (Pf):
- Spoon (Ps):
Predator efficiency = single predator/total predator x 300
Part 2
- Write down the total number of prey remaining from the first generation.
- Red beans:_______
- White beans:_______
- Green peas:__________
- Lima beans:_________
- Repeat Part 1, using the remaining beans in the box.
Data Table 2: Second Generation
| Red | White | Green | Lima | |
| Knife | ||||
| Fork | ||||
| Spoon |
- Total each:
- Total all:
Predator Efficiency for:
- Knife (Pk):
- Fork (Pf):
- Spoon (Ps):
Predator efficiency = single predator/total predator x 300
- Write down the total number of prey remaining from the first generation.
- Red beans:_______
- White beans:_______
- Green peas:__________
- Lima beans:_________
- Repeat Part 1, using the remaining beans in the box.
Part 3
Data Table 3: Third Generation
| Red | White | Green | Lima | |
| Knife | ||||
| Fork | ||||
| Spoon |
- Total each:
- Total all:
Predator Efficiency for:
- Knife (Pk):
- Fork (Pf):
- Spoon (Ps):
Predator efficiency = single predator/total predator x 300
- Write down the total number of prey remaining from the first generation.
- Red beans:_______
- White beans:_______
- Green peas:__________
- Lima beans:_________
- Repeat Part 1, using the remaining beans in the box.
Questions:
- Which predator (knife, fork, and spoon) was the most successful in obtaining prey? Why do you think so?
- Which prey was the most successful at escaping the predator? Why do you think so?
- Which prey was picked up the most often, or least successful in escaping? Why do you think so?
- In which generation were the numbers of successful and unsuccessful groups changing the fastest? Why do you think so?
- What do these results indicate about environmental influences on predator-prey evolution?
- What do you think would be the ultimate fate, given enough generations, of these predators and prey?
- What contributions did Erasmus Darwin make to the theory of evolution?
- Describe the theory of natural selection as refined by Charles Darwin.
- What does “survival of the fittest” mean to you?
- How does number 9 apply to human populations, or does it?
NGSS Standards:
LS2.C: Ecosystem Dynamics, Functioning, and Resilience
- When the environment changes in ways that affect a place’s physical characteristics, temperature, or availability of resources, some organisms survive and reproduce, others move to new locations, yet others move into the transformed environment, and some die.
LS4.A: Evidence of Common Ancestry and Diversity
- Some kinds of plants and animals that once lived on Earth are no longer found anywhere.
- Fossils provide evidence about the types of organisms that lived long ago and also about the nature of their environments.)
LS4.B: Natural Selection
- Sometimes the differences in characteristics between individuals of the same species provide advantages in surviving, finding mates, and reproducing.
LS4.C: Adaptation
- For any particular environment, some kinds of organisms survive well, some survive less well, and some cannot survive at all.
LS4.D: Biodiversity and Humans
- Populations live in a variety of habitats, and change in those habitats affects the organisms living there. (3-LS4-4)
The performance expectations in LS4:
- Biological Evolution: Unity and Diversity help students formulate an answer to the question, “How do organisms change over time in response to changes in the environment?” The LS4 Disciplinary Core Idea is divided into four sub-ideas: Evidence of Common Ancestry and Diversity, Natural Selection, Adaptation, and Biodiversity and Humans. Students can construct explanations based on evidence to support fundamental understandings of natural selection and evolution. They can use ideas of genetic variation in a population to make sense of organisms surviving and reproducing, hence passing on the traits of the species. They are able to use fossil records and anatomical similarities of the relationships among organisms and species to support their understanding. Crosscutting concepts of patterns and structure and function contribute to the evidence students can use to describe biological evolution.
By aroth
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