Download How Genes Work With Evolution

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How Genes Work With Evolution
BACKGROUND
Over time, changes in an environment may occur. The individuals with traits that
make them more adapted to the changed environment tend to survive and leave more
kids. The genes that determine these traits are most likely to be passed on from one
generation to the next.
MATERIALS
Container such as a plastic container
Pencil or pen
1 cup labeled “dead”
Red beans, 40
White beans, 40
PROCEDURE
1. Place all the beans in the plastic container. Put the lid on it and gently shake it to
mix the beans.
2. These beans will represent the genes of a lizard living in the White Sand Dunes
National Monument in New Mexico. The plastic container holds the sex cells
from forty adults of the lizard population. Assume that the white gene 1 is
dominant over the red gene (2) so that the 1,1 and 1,2 show white and 2,2 shows
red. Scientists have determined that coloration is caused by a single gene.
3. Remove the cover from the container. Close your eyes and take out two beans
from the container. These are the genes of a new baby lizard, one from mom and
one from dad. Record what the kids looks like and what its genes are in the
Generation 1 table.
4. Put the genes back in the box. Keep recording your data in Table 1 until you have
40 “kids.” You will NOT use the jar marked “dead” in this round.
GENERATION 1 TABLE
Genes
Number of 1,1
Number of 1,2
Number of 2,2
Looks Like
Number of White
Number of Red
5. Repeat steps 1-5 except, this time if you get a red kid, place the two red beans in
the cup labeled “dead.” The lake near their home has dried up leaving white
gypsum (used in drywall) as the environment. An equal amount of lizards
migrate into the new land. (This actually happened 7000 years ago.) Now every
other red lizard dies before it can reproduce because it does not blend in as well as
it did with the red rocks surrounding the dried up lake and gets eaten by predators.
Place the genes from the red lizard #1 in the “dead” cup, red lizard #2 in the
parent plastic container, #3 in the “dead” cup, #4 in the parent plastic container,
etc. Place the genes from all white lizards in the parent plastic container. Record
your results in the Generation 2 Table.
6. Continue until you have 40 “kids.” DO NOT put the genes from the dead lizards
back in the parent plastic container. Once dead, lizards do not reproduce and pass
on their genes.
7. Repeat and record your results in the Generation 3 & 4 Table.
Generation 2 Table
Genes
Number of 1,1
Number of 1,2
Looks Like
Number of White
Number of Red
Number of 2,2
Generation 3 Table
Genes
Number of 1,1
Number of 1,2
Number of 2,2
Looks Like
Number of White
Number of red
Generation 4 Table
Genes
Number of 1,1
Number of 1,2
Looks Like
Number of White
Number of Red
Number of 2,2
Analysis Questions
1. What variations of trait of coloration were present in the lizard population? (What
colors of lizards were there at the beginning of the activity?)
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2. What variation of coloration had more individuals survive at the end of four
generations? ___________________________________________________
3. Look at the variation of lizards that had the most individuals survive. What is the
selective advantage of this variation? (In other words, how does that color let
individuals survive instead of other members of the species?)
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4. What variations (colors) were present in the population of lizards at the end of
generation 4?
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5. Was there a change in the number of lizards of each variation (color) during the
four generations of the activity? Which color had the most left? Explain.
6. How do you know that the trait in this activity is inherited?
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7. Scientists have also determined that white male lizards are attracted more to white
females than to red female lizards and mate with them more often. How would this
effect the population?
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