Student Exploration: Evolution: Mutation and Selection
Vocabulary: adaptation, allele, allele sequence, chromosome, evolution, fitness, gene, genotype, mutation, natural selection, phenotype, trait
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
Imagine a white lizard and a brown lizard sitting on a brown rock. A hawk is circling overhead hunting for its next meal. Which lizard do you think the hawk would most likely try to catch? Explain your choice.
Now imagine that the same two lizards were sitting on a dune of white sand. Which lizard do you think the hawk would then most likely try to catch? Why?
How long could a parrot survive in Antarctica? It would probably not survive long. Parrots do not have adaptations—or helpful characteristics—to survive icy cold weather. Because of this, a parrot is not fit for Antarctica. Fitness describes how well an organism can survive and reproduce in an environment.
In the Evolution: Mutation and Selection Gizmo™, you will see how a species’ fitness can change over time as it becomes better adapted to its environment.
On the SIMULATION pane, what is the Average fitness of the population?
On the CONTROLS pane, experiment with the Background color sliders.
Which background color results in the highest fitness?
Which background color results in the lowest fitness?
Get the Gizmo ready:
Set Red to 100, Green to 255, and Blue to 50.
Introduction: An organism’s traits, or characteristics, are controlled by genes. Genes are located on rod-like structures called chromosomes. Different versions of genes that code for the same trait are called alleles. In this Gizmo, there are 3 genes on each chromosome. For each gene there are eight possible alleles: W (white), R (red), G(green), B (blue), C (cyan), M (magenta), Y (yellow), and K (black).
Question: Where does variation in a population come from?
Observe: Hold your cursor over one of the insects. The two rod-like structures under Genotype on the right side of the Gizmo represent chromosomes. The three letters next to each chromosome represent alleles.
Which alleles does the insect have?
The alleles carried on an organism’s chromosomes make up the organism’s genotype.
Observe: An organism’s alleles combine to produce a trait. The physical expression of that trait is a phenotype. In the Gizmo, phenotype is expressed in red, green, and blue values.
What is the phenotype of the insect? Red: Green: Blue: