Question

For this exercise we will be re-enacting founder effect on a population of hypothetical people. You can use red and white beans (or any other small household item that comes in two colors) to complete the exercise. The beans will represent genes and the different colors will represent different alleles (gene variants). Red beans will represent the dominant (R) allele for the trait, while white beans will represent the recessive (r) allele.

Humans have two copies of each gene, so we will represent each person with two beans. A person with two red beans will be homozygous dominant (RR), a person with one red and one white will be heterozygous (Rr), and a person with two white beans will be homozygous recessive (rr).

Begin by placing 20 red beans and 20 white beans inside a small to medium cup.

A. Assess the original gene pool. How many alleles of each kind are present in your overall population?

Dominant: 0, Recessive: 40

Dominant: 40, Recessive: 0

Dominant: 20, Recessive: 20

Dominant: 20, Recessive: 0

Dominant: 0, Recessive: 20

B. Oh no! Five people from the original population went on a three hour boat tour and ended up stranded on a deserted island. From the original gene pool (your cup of beans) select the surviving subpopulation (Founding Population #1).

Randomly draw out the alleles of five individuals (5 pairs of beans) that will represent the individuals stranded on the island.

a) Record the genotypes of the five individuals in Founding Population #1 below.

b) What is the total number of dominant and recessive alleles present in Founding Population #1

C. As this surviving population mates, and the population increases again, will it differ from the original, larger population? Why or why not?

D.Now, a hurricane strikes the island and two people are swept away and land another remote island. From the first founding population, select a second subpopulation (Founding Population #2).Return the alleles (beans) from the 5 people in Founding Population #1 to the gene pool (cup). Randomly draw out two individuals that survive (two pairs of beans).

a) Record the genotypes of the two individuals in Founding Population #2 below.

b) What is the total number of dominant and recessive alleles present in Founding Population #2

E. Does this founding group #2 differ from founding group #1 above? Why or why not?

F. Does this founding group #2 differ from the original, larger population? Why or why not?

G. How might the size of the founding group impact the effects of genetic drift?

The smaller the founding group, the more dramatic the impact.

The larger the founding group, the more dramatic the impact.

The size of the group has no impact on the effects of genetic drift.

Answer 1

A) Dominant 20 and Recessive 20 beacuse Dominant allele = RR ,Rr and recessive = rr and there are 20 red beans and 20 white beans .

B) Randomly selected individualsfor founding population f1 : (Rr), (rr ), (RR) , (rr ) , (rr ) . # of dominant alleles : 3 and # of recessive alleles : 7

C) yes the founder population f1 will differ from the original population . There is essentially a sampling difference . The founder effect results in radical changes in alleles frequencies . Original population has allele population of ( p= 0.5 & q = 0.5 ) but the founder population has allele frequency ( p = 0.3 & q = 0.7 ) . So , allele frequencies changed .

D) Genotype of founding population f2 : (Rr ) , (rr) . # of dominant alleles : 1 and # of recessive alles : 3 .

E) yes f2 differ from f1 beacuse f2 allele frequencies again changes from ( p = 0.3 & q =0.7 ) to (p = 0.25 and q = 0.75 ) .

F ) yes f2 also differ from original population in terms that it has reduced genetic variation from original population , changed allele frequency from original population .

G) The smaller the founding group , the more the dramatic impact . It can be observed from f1 and f2 . F2 has small number of individuals so , it had more profound effect .