Population genetics 4b (Textbook)

Question 1

bottle neck

Answer 1

sudden drop in population size

Question 2

Phenotypic variation + example (2)

Answer 2

Differences in appearance or function

For example, in a population, although the members look alike, they are not identical. You could detect differences in their weight as well as length and diameter of their shells, and individual biochemistry, physiology and behaviour.

Question 3

Quantitative variation+ex (2)

Answer 3

individuals differ in small incremental ways

For example, humans exhibit quantitative variation in the length of their toes, number of hairs and their height.

Question 4

When we display quantitative variation in a bar graph, what information does the graph tell us? (2)

Answer 4

The width of the curve is proportional to the amount of variation among individuals and the mean describes the average value of the character.

Question 5

Qualitative variation

Answer 5

Characters that exist in two or more discrete states. You have either blue or brown feathers.

Question 6

Polymorphic traits+ex (3)

Answer 6

traits that are associated with two or more genes. Polymorphic traits, such as the difference in skin and eye color and height, result from more than one gene.

So basically more than one form

Polymorphism does not cover characteristics showing continuous variation (such as weight), though this has a heritable component. Polymorphism deals with forms in which the variation is discrete (discontinuous)

Question 7

How do you describe phenotypic polymorphism quantitatively?

Answer 7

By calculating the frequency of each trait. You take the individual trait number and divide it by total of all the possible trait forms.

For ex: if you counted 123 blue geese, and 369 white in a population of 492, the frequency of blue is 123/492=0.25

Question 8

phenotypic variation is caused by (2)

Answer 8

genetic differences between individuals and environmental factors

Question 9

The organism’s phenotype is often the

Answer 9

product of an interaction between its genotype and its environment as environmental factors influence the espression of genes.

Question 10

Population genetics

Answer 10

Focuses on the genetic variation that exists within a population and how this changed over time due to evolution.

Question 11

Evolution can be caused by four distinct processes:

Answer 11

1. Mutation
2. Genectic drift
3. Gene flow
4. natural selection

Question 12

Trait

+ how they are determined

Answer 12

Inherited characteristic of an individual related to their appearance, abilities and behaviours.

Some are coded by single genes while others are coded by the result of many genes

Question 13

Locus

Answer 13

Location of a gene on a chromosome

Question 14

Changing how common a particular allele is within a population changes

Answer 14

the genetic makeup of the population.

Question 15

Gene pool

Answer 15

The total genectic variability of a poopulation by all the alles at all the gene loci in all individuals within the population

Question 16

Sum of allele frewuency and genotype frequencues…

Answer 16

must equal 1

Question 17

Hardy Weinberg equilibrium (2)

What it is No listing of the 5 conditions

Answer 17

• a null hypothesis for evolution
• A mathmatical model that soecifies the conditions that are nescessary so that allele frequencies and genotype frequencies do not change from one generation to the next

Question 18

According to Hardy Weinberg, ——-is possible only if all the following conditions are met (6)

Answer 18

genectic equilibrium is possible only if:
1. The population is closed to migration from one another
2. The population is infinite in size
3. No mutation is occuringin the population
4. All geneotypes in the population survive and reprodice equally well
5. Individuals in the population mate randomly with respect to genotype

Question 19

How to find allele frequency (4)

Answer 19

1. List all the Genotypes : RR, RW, WW
2. Multiply genotype by 2 or 1 or 0 (recessive when finding dominant) to find the allele. For example finding the R allele you multiply RR by 2, RW by 1 and WW by 0
3. Add up the allele (ex: R allele from RR, RW and WW)
4. Divide that by total amount of allele for all allele

Question 20

Finding genotype frequencies

Answer 20

The number of individuals possesing a particular genotype divided by the total number of inidivduals in the sample

Question 21

What happens if one of the 5 conditions of the Hardy Weinberg model is violated?

Answer 21

A population’s allele frequencies will change over time

Question 22

How does population migration change allele and genotype frequencies and lead to evolution? (2)

What is this called?

Answer 22

Organisms and their gametes sometimes move from one population to another and may introduce novel alleles into a population shifting its allele and genotype frequencies away from the values perficated by the Hardy Weinberg model.

This is called gene flow

Question 23

The importance of gene flow in driving evolutionary change within a population depends on (2)

Answer 23

how different the gene pool is between it and other populations and the rate of gene flow into and out of the population

Question 24

While gene flow increases genetic diversitiy in one population,….. as a result….

Answer 24

It reduces the genetic differences between the populations.

adjacent populations tend to share many of the same alleles and high rates of gene flow can reduce the genetic differentiation between the two groups, increasing homogeneity

Question 25

Small populations that are the results of bottle necks have low ——- ——- and have limited ——–

Answer 25

genectic diversity

ability to survive unfavourable enironmental changes