(classical genetics) mechanisms of how genes and traits are transmitted from generation to generation

Examples: Patterns of trait inheritance, role of mitosis and meiosis

Population Genetics

heredity in populations for traits determined by one or few gene

Examples: 1) Genetic variation in populations. 2) Mechanisms producing deviations/variations between populations. 3) Factors that influence genetic variation within a population.

Quantitative Genetics

heredity in populations for traits determined by many different genes.

Examples: 1) Degree of phenotype variation caused by genotype variation. 2) How many genes are involved; are there affects additive, are there contributions equal.

Which of the following have to do with Mathematics in Genetics?

a) Quantitative

b) Molecular

c) Transmission

d) Population

a) Quantitative & d) Population

What are Genotype Frequencies?

The proportion of individuals in a population sharing the same genotype

What is the equation to find genotype frequency?

f = number of individuals with the genotype/ total number of individuals in the population

Allele frequency is important to understand what?

Fluctuations in the gene pool

What is the equation for allele frequency?

f = number of copies of each allele/ sum of all alleles in population

What are the equations for determining frequency of 2 alleles?

p = f (A) = (2 x count of AA) + (count of Aa)                                      2 x number of individuals

q = f(a) = (2 x count of aa) + (count of Aa) = 1-p

                    2 x number of individuals

What are the equations for determining the frequency of 3 alleles? (p,q,and r)

p = f(A¹) = (2 x count of A¹A¹) + (count of A¹A²) + (count of A¹A³) / 2 x number of individuals

q = f(A²) = (2 x count of A²A²) + (count of A¹A²) + (2 x count of A²A³) / 2 x number of individuals

r = f(A³) = (2 x count of A³A³⁾ + (count of A¹A³) + (2 x count of A²A³) / 2 x number of individuals

Why was the Hardy-Weinberg Principle developed?

in response to the question as to why the dominant allele doesn't always become the most frequent in a population.

What is the Hardy-Weinberg Principle?

A math principle that examines allele frequencies in a population to determine if the population is in equilibrium.

What assumptions must be made to prove Hardy-Weinberg equilibrium?

1. Population must be infinitely large; if too small genetic drift comes into play.

2. Population must randomly mate (with respect to the allele in question)

3. Population must be free from migration, mutation and natural selection (with respect to the allele in question)

What results are required for Hardy-Weinberg equilibrium?

1. Frequencies of alleles do not change over time

2. Genotype frequencies remain the proportion

    p², 2pq and q², where p² + 2pq + q² = 1

Define Extrinsic Hypothesis

Knowing up front or in advance the expected. (upfront you know)

degrees of freedom = n-1

Define Intrinsic Hypothesis

We determine the expected from the observations

degrees of freedom = phenotype classes (n) - 2

Does Chi-Square analysis use an extrinsic or intrinsic hypothesis?

Extrinsic Hypothesis

Does Hardy-Weinberg use an extrinsic or intrinsic hypothesis?

Intrinsic hypothesis

What is an allelic frequency cline?

When populations show different allelic frequencies across

geographic transects. (The mussel example)

What phenomena could alter existing genetic variations?

(5)

1. Mutations

2. Natural Selection

3. Random genetic drift

4. Migration

5. Nonrandom mating

What are mutations?

introduction of new alleles into the population.

What is Natural Selection?

When the environment selects for certain traits that favor survival of beneficial traits or disfavoring the survival of individuals with unfavorable traits.

What is Random Genetic Drift?

Random sampling errors that lead to genetic variations b/t generations. Common in smaller populations; loss of alleles.

What does Migration cause?

Migrations b/t populations with different allelic frequencies alter frequencies in the recipient population.

What is nonrandom mating?

When individuals select mates based upon phenotypes or genetic lineage.

Does Nonrandom mating alter rates of homozygotes/heterozygotes or allelic frequency?

rates of homozygotes and heterozygotes

Does Nonrandom mating alter phenotypic or genotypic frequencies?

genotypic frequencies

What is Absolute Fitness?

average reproduction rate w/in individuals of the same genotype.

ratio of individuals that have a particular genotype before and after a single generation.

What is Relative Fitness?

The ability of a genotype to survive and reproduce in comparison to other genotypes in the population

What 2 things does Relative Fitness involve?

1. Fecundity - number of offspring born to a female of a certain genotype

2. Survival - offspring surviving to sexual maturity

Can both natural and unnatural selection alter allelic frequencies? If yes, what fitness does it alter?

1.Yes any type of selection can alter allelic frequencies.

2.Relative fitness is altered.

List the 3 types of Natural Selection

1. Directional Selection

2. Stabilizing Selection

3. Disruptive Selection

What is Directional Selection?

Removes 1 extreme from 1 end of a phenotypic distribution. Shifts the population and the mean.

What is Stabilizing Selection?

Removes both extremes from the distribution. Doesn't change mean or allelic frequency. Lowers the chances of having a homozygous group for the extremes.

What is Disruptive Selection?

Favors the extremes and decreases the heterozygotes. Messes with the means.

What is the ultimate source of variation?

Mutations

What type of natural selection does Malaria provide for?

Stabilizing Selection

Sickle cell anemia selects for what type of Natural Selection?

Stabilizing Selection

What is Frequency-Dependent selection?

Fitness of an individual allele depends on the frequency of other alleles/genotypes in the population.

Give an example of a Frequency-Dependent selection.

The Parasotous Microlepsis (fish) - eat scales of other fish

What is Density-Dependent Selection?

Phenotypes that benefit organisms only when populations density changes.

What is an example of Density-Dependent selection?

The forager phenotype in drosophila.

Random Genetic Drift

Refers to alteration of allele frequencies due to random chance.

Bottleneck Affect

changes in population size due to natural or man-made disasters can lead to random elimination of individuals. Leads to less diversity.

Founder Effect

When a new population is initiated by few individuals; founders will have less diversity than the original population.

Allele frequencies in populations can be altered by what?

Migration, which causes gene flow into another population.

What effects (3) play a role in altering population?

The effects of 1. Migration, 2. Genetic Drift, 3. Natural Selection

Inbreeding

the mating of related individuals

In a large population, does inbreeding change both allelic and genotypic frequencies? If so, how?

Genotypic frequencies are changed by increasing homozygosity.

Inbreeding Depression

Reduction in fitness due to accumulation of homozygotic deleterious recessive alleles which lead to a lowered mean fitness.

Assortative Mating

mates have are chosen because they share common traits. Increases homozygosity, but not for the entire genome.

Disassortive Mating

What does Quantitative Genetics examine?

How genes interact with the environment to give a continuous distribution of phenotypes for a specific trait within a population.

Why is Quantitative Genetics important/necessary for?

1. Evolutionary Biology

2. Ecology & conservation biology

3. Medical Biology

Heart Disease and Cancer are both examples of Population or Quantitative Genetics?

Quantitative Genetics

Most Quantitative traits are what?

Polygenic

What are 3 types of polygenic traits?

1. Continuous traits

2. Threshold traits

3. Meristic traits

Continuous Traits

can take on an infinite number of values, limited only by precision of the instruments (height & weight)

Threshold Traits

Places arbitrary threshold; Once you reach a certain level you have the disease or you don't.

Give an example of threshold traits

Cancer & Heart Disease

Meristic Traits

Traits that vary by whole number only.

(puppies in a liter, petals on a flower)