Lec 13-1

Question 1

Population genetics

Answer 1

Study of genetics at a population level

Question 2

Ancestor Finch population

Answer 2

Had variation in beak size and shape

Certain finches with some alleles thrived under changing conditions

Question 3

Much of trait variation is derived from

Answer 3

Variation at the molecular/genetic level

Thus is inheritable

Question 4

Population genetics definition

Answer 4

Branch of genetics that studies the genetic makeup of groups and how group’s genetic composition changes over time

Question 5

Mendelian population

Answer 5

A group of interbreeding sexually reproducing individuals that have a common set of alleles, a GENE POOL

Question 6

Example of Mendelian Population

Answer 6

Wolves of Isle Royale

In 1949 single breeding pair of wolves
crossed frozen ice and populated Isle
Royale

1959 - 20 wolves
1980 – 50 wolves

Cut off from mainland populations
interbreeding

This is an example of a Mendelian
population with a common gene pool

Question 7

Sometimes a Mendelian population is

Answer 7

Too large to practically measure all the alleles/genotypes

In these cases, a representative sample of the population is considered and then the results are extrapolated to the entire gene pool

Question 8

In order to understand how genetic variation changes in a
population over time,

Answer 8

Need to mathematically describe the gene pool

Question 9

Gene pools can be described by the types and frequencies of

Answer 9

Genotypes in the population

Alleles in the population

Question 10

Sum of all genotypic frequencies always equals

Answer 10

1

Question 11

Gene pools can also be described by

Answer 11

Allelic frequencies

Question 12

Different genotypes are just

Answer 12

Rearrangements of a set of alleles

Question 13

There is always less

Answer 13

Alleles than genotypes

Question 14

Allelic frequencies can be calculated in either of 2 ways:

Answer 14

1. counting numbers of alleles
2. the frequencies of genotypes

Question 15

Calculating genotypic frequencies

Answer 15

f(AA)= Number of AA individuals/ N

f=frequencies

Question 16

Calculating Allelic Frequencies by Counting Alleles

General equation

Answer 16

Frequency of an allele= number of copies of the allele/ number of copies of all alleles at the locus

AA=two alleles for the letter A

Question 17

For locus with two alleles (A and a)

Equation

Answer 17

p= f(A)= 2nAA + nAa/2N

q=f(a)=2naa + nAa/2N

also p+q=1

N=population size

n= number with a certain genotype

Question 18

For locus with two alleles (A and a)

Equation

only works for

Answer 18

2 alleles and autosomal

Question 19

Calculating allelic frequencies for more than 2 alleles

From genotype numbers

Answer 19

slide 24

Question 20

Calculating allelic frequencies for more than 2 alleles

From genotype frequencies

Answer 20

slide 25

Question 21

How does segregation of alleles in gamete formation and then the combining of alleles during fertilization alter the genetic structure of a popualation

Answer 21

Hardy-Weinberg Law

Question 22

G.H. Hardy and Wilhelm Weinberg

Answer 22

Made the Hardy-Weinberg Law

Question 23

Hardy Weinberg Law

Answer 23

Mathematical model evaluating the effect of reproduction on genotypic and allelic frequencies of a population

Among the most important principles in population genetics

Question 24

Assumptions of Hardy Weinberg

Answer 24

• Population is large
• Random mating
• No mutations, migration, or natural selection

Question 25

Predictions of Hardy Weinberg

Answer 25

1. Allelic frequencies of a population do not change 2. Genotypic frequencies stabilize (will not change) after one generation Genotypic frequencies will be Frequency of AA = p2 Frequency of Aa = 2pq Frequency of aa = q2 Where p = f(A) and q = f(a)

Question 26

In other words, The Hardy-Weinberg Law says that if the assumptions are met,

Answer 26

Reproduction does not itself alter allelic or genotypic frequencies

Question 27

Hardy Weinberg States that after a generation of random mating

Answer 27

genotypic frequencies should stabilize and achieve the Hardy-Weinberg proportions

Question 28

When genotypes are in the expected proportions of p2 (AA), q2(aa) , and 2pq (Aa),

Answer 28

the population is said to be in Hardy Weinberg equilibrium