Download Original Population

Frequency of traits in a population
Allele frequency – the frequency of an allele in a population. Determined by dividing the number of a certain allele by
the total number of alleles in the population.
Phenotypic frequency – the frequency of a particular phenotype in a population. Determine by dividing the number of
individuals with the phenotype by the total number of individuals in the population
Gene pool – total genetic information available in the population
Example: The color of a particular flower is determine by one gene with 2 alleles. There are 500 flowers in the
population. There are 160 red (RR), 320 pink (Rr) and 20 white (rr). Calculate the following frequencies:
Red 160/500 = .32 = 32%
A = (160 + 160 + 320)/1000 = 640/1000 = .64 = 64%
Pink 320/500 = .64 = 64%
White 20/500 = .04 = 4%
a = (20 + 20 + 320) /1000 = 360/1000 = .36 = 36%
Hairy caterpillars have one gene that determines their shell color. Caterpillars can be solid green (GG), solid white (gg)
or spotted (Gg). There are 245 white caterpillars, 210 spotted and 45 green. Calculate the following frequencies:
Green
Spotted
White
G
g
A new predator (non- native) is accidently introduced into the area and it loves to eat hairy caterpillars, especially the
spotted ones. After several generations there are now 310 white, 50 spotted and 140 green. Calculate the following
frequencies:
Green
spotted
White
G
g
Did the frequencies change from the original population to the current one?______________________
What does this change in frequency mean?_____________________________________________
What is causing the change?_________________________________________________
** Today you will be calcualting the frequencies in a population of Smartus colorus in Franklinville.
S. colorus is a small bird that lives in the trees.
Directions:
1. Obtain your population of organisms and place them on your paper towel. DO NOT EAT THEM!!!! (yet!)
2. Count the total number of organisms and record in the first data table.
3. Count the number of each color of S. colorus , and record these numbers in your data table.
4. Determine the phenotypic frequency of each color S. colorus of each color by the total. Record this information in
your table. These are the frequncies of each trait in your population.
5. You are a new introduced predator to the habitat. In your search for food, you find that the green variety of S.
colorus are the easiest to capture. As a result, you eat all but one of them.
6. Place the new data on the second data table and recalculate the color frequencies as you did above.
What effect does the loss of all but 1 green have on the gene pool?
What is the future fate of the green gene in the population?
Taking into account the physical or anatomical features of birds, make a list of 6 hypothetical characteristics that
might make the green birds (or any bird) more vulnerable to predation.
7. Randomly scatter your candy across the paper towel.
8. Raise your hand and wait for the teacher. A large geographical change has occurred in your population and they are
separated into 2 groups.
9. What is the total number of S. colorus in population 1? In pop 2? Calculate the phenotypic frequencies for each
10. After checking to make sure that you have all data filled in completely enjoy your snack!
Original Population
After Predation of green
Total Number of smarties in the population _________
Total Number of smarties in new population:__________
Colors
Number of
Frequency in the
Color
Of smarties
Each color
Original Population
Number each
Frequency
color
After Geographical separation
Total Organisms in Population #1___________
Color
Number each Frequency
color
Total Organisms in Population #2___________
Color
Number each Frequency
color
Questions:
1. What does each smartie represent?
2. What does each color group of smarties represent?
3. What does each large group of smarties represent?
4. Using the table, what happened to the frequences of the new population (#2) compare to the original? BE
SPECIFIC!!
5. Using the table, what happened to the frequencies of the populations after the geographic event separated
them? BE SPECIFIC!
6. Brainstorm 7 things that could happened that would cause 2 populations to become geographically separated.
7. What happened to the gene pool after the geographically separation?
8. Do you think new species could arise because of this? Why?