Download Grade 11 University Biology – Unit 3 Evolution

Grade 11 University Biology – Unit 3 Evolution
Natural Selection – Simulation
Darwin described Natural Selection as the way in which the environment (nature) favours the
reproduction of certain individuals over others. In other words, living things are adapted to
survive and reproduce in their environmental setting, AND an organism with traits that provide an
advantage is more likely to survive, reproduce and pass its advantageous traits to its offspring.
This activity will involve Smarties. There are red and green Smarties. Our Smarties live in a
green grass environment. The friendly and cheerful Smarties have only one real concern: you
(…a predator).
We will put them in an environment that has the necessary components for evolution by natural
selection.
 Variation – For natural selection to occur, individuals in a population must have different
characteristics. In this activity, red and green colours represent within population
variation. Moreover, the predators have different foraging strategies and structures: (1)
collect Smarties with their elbows only, (2) collect Smarties with a knife and (3) collect
Smarties by pinching the food between their thumb and baby finger.
 Differences in Fitness – For natural selection to occur, the different characteristics of
different individuals must contribute to differences in fitness (i.e., differences in their
ability to survive and reproduce). So, variation in Smarties colour will influence the
probability that the Smarties will be found and consumed. Likewise, it seems possible
that the different predator feeding strategies may vary in their success in finding and
consuming Smarties. These differences contribute to the survival and reproductive
success of the population
 Heritability of Characteristics – For natural selection to occur, the characteristics that
affect fitness must be heritable (i.e., passed by genes from one generation to the next).
In the activity, a Smartie is born into the Smarties population in the same colour as its
parent AND a predator is born into the hunter population has the same feeding strategy
as its parent.
Task – Instructions
 Split the class into three groups. Each group represents one of the predator feeding
strategies. There should be an equal number of predators per group.
 Make sure you have your knife if you are a member of Group 2
 Each predator should also have a cup…for holding Smarties. The cup represents the
stomach of the predator.
 Move outside (optional)
 The Smarties are placed randomly in the grass (e.g., tossed into the air). There should
be an equal number of red and green Smarties at the beginning of the activity. Which
Smarties trait will provide an advantage to survival?
 Begin hunting and foraging. To collect a Smartie, you can only use your assigned
feeding strategy AND you must put each collected Smartie in your cup. As well, you can
compete (e.g., run from Smartie to Smartie, “take” a Smartie from under the nose of
another predator) BUT you cannot take Smarties from another predator’s cup (i.e., once
the Smartie is eaten, it is gone from the activity).
 Forage for five minutes.
 When the command “STOP” is given, stop foraging immediately
 Count the number of green Smarties and red Smarties, and record the information on the
Class Datasheet
 Arrange yourself in a line with your class. The predator collecting the fewest Smarties is
the beginning of your line, while the end of your line is the most successful predator.
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Only the top 50% of predators survive. Those who die will be “reborn” as the offspring of
the survivors. The new predators now have the feeding strategy of their parents.
The teacher will count out the number of Smarties of each colour eaten and calculate the
number of each colour surviving the predators. The surviving Smarties will reproduce at
a rate of three offspring per parent.
Repeat the simulation
From the collected data, calculate the percent of Smarties that are (1) red and (2) green.
Similarly, calculate the percent of each feeding strategy among the predators.
Did evolution by natural selection occur in each Smartie population? In other words, did
one colour of Smartie become more common? What traits contributed to the survival of
the Smarties?
For each predator group, determine what traits contributed to the survival of the group.
For each predator group, what feeding typed become more positive? That is, what trait
contributed to the survival of the hunters and let them reproduce?
If we repeated the experiment 50X, what would you predict about the colours
Summarize your findings and present the information.