Chapter 19

Question 1

What is genetic drift?

Answer 1

Genetic drift represents chance events that can cause allele frequencies to fluctuate

Question 2

Genetic drift is ________ in small populations

Answer 2

Amplified (smaller numbers means that something random like disease can wipe out way more and do a lot more damage)

Question 3

The 4 postulates of the Theory of Natural Selection

Answer 3

1) There is variation among individuals within populations.
2) At least some of the variations among individuals are hereditary
3) In every generation some individuals are more successful at surviving and reproducing than are others.
4) Survival and reproduction are not random.

Question 4

What will occur if the 4 conditions of Natural Selection are met?

Answer 4

The population will change from generation to generation

Question 5

What is “pop gen”?

Answer 5

Population genetics deals with the genetic differences within and between populations

Question 6

Epistasis

Answer 6

Expression of one gene affects the expression of other genes

Question 7

For every ____ gene there are ____ alleles and ____ genotypes.

Answer 7

1- Gene “A”
2 - A & a
3 - AA, Aa, & aa

Question 8

“Pop gen” is centered around what 3 main concepts?

Answer 8

1:2:3, the five tenets of Hardy-Weinberg equilibrium, and the 2 Hardy-Weinberg equations

Question 9

Hardy-Weinberg two equations

Answer 9

P + Q = 1
P2 + 2PQ + Q2 = 1

Question 10

P + Q = 1

Answer 10

P = frequency of dominant alleles
Q = frequency of recessive alleles

Question 11

P2 + 2PQ + Q2 = 1

Answer 11

P2 = % of pop. that is homozygous D
2PQ = % of pop. that is heterozygous
Q2 = % of pop. that is homozygous R

Question 12

If a population is in Hardy-Weinberg equilibrium, then …..

Answer 12

… the allelic frequency is stable (no changes in P & Q, no microevolution)

Question 13

The Hardy-Weinberg equations are used for what?

Answer 13

To determine the distribution of alleles IF the population is in Hardy-Weinberg equilibrium

Question 14

Locus

Answer 14

Location of a gene on a chromosome

Question 15

The Hardy-Weinburg equation describes the….

Answer 15

… genetic makeup we expect for a population that is NOT EVOLVING

Question 16

5 conditions for Hardy-Weinberg Equilibrium (AKA non-evolving populations)

Answer 16

1. No mutations
2. Random mating
3. No natural selection
4. Extremely large population size
5. No gene flow (no migration)

Question 17

How is is possible for populations to evolve and be in Hardy-Weinberg equilibrium?

Answer 17

They can evolve at some loci, but be in equilibrium at other loci (place on chromosome where gene is found)

Question 18

What three main factors alter allele frequency and bring about evolutionary change?

Answer 18

Natural selection (for or against), genetic drift (randomness), and gene flow (migration)

Question 19

Natural selection

Answer 19

Differential success in reproduction results in certain alleles being passed to the next generation in greater proportions

Question 20

How does anti fungal/antibiotics work?

Answer 20

They are designed to attack something that the host does not have (so it only hurts the disease)

Question 21

The smaller the sample…

Answer 21

… the greater the chance of random deviation from a predicted result

Question 22

The Founder Effect

Answer 22

The Founder Effect occurs when a few individuals become isolated from a larger population (ex. Birds are blown from the mainland to an island and start a population)

Question 23

The Bottleneck Effect

Answer 23

The Bottleneck Effect is a sudden reduction in population size due to a change in the environment (like disease or natural disaster)

Question 24

What can be a possible effect of the Bottleneck Effect?

Answer 24

The resulting gene pool may no longer be reflective of the original gene pool

Question 25

Gene Flow

Answer 25

(AKA migration) the movement of alleles among populations

Question 26

Examples of Gene Flow

Answer 26

Pollen grains in the wind, insects being blown somewhere new, people moving to a different country, etc.

Question 27

What does gene flow tend to do to populations overtime?

Answer 27

Reduce variation, b/c alleles that have a selective advantage are the ones being moved b/c those individuals are still alive and carrying them

Question 28

Relative Fitness

Answer 28

The more “fit” an individual is, the greater the chance of their survival and later reproduction (genes are passed)

Question 29

Selection favors certain ______ by acting on the ______

Answer 29

Genotype, phenotype

Question 30

5 Selection Pressures

Answer 30

Directional, Sexual (Intra & Inter), Disruptive, and Stabilizing Selection

Question 31

Directional Selection

Answer 31

favors individuals at one extreme end of the phenotypic range

Question 32

Disruptive (Divergent) Selection

Answer 32

favors individuals at both extremes of the phenotypic range

Question 33

Stabilizing Selection

Answer 33

favors intermediate variants and acts against extreme phenotypes

Question 34

Sexual Selection

Answer 34

Natural selection for mating success (think courtship rituals)

Question 35

2 Types of Sexual Selection

Answer 35

Intrasexual and Intersexual selection

Question 36

Intrasexual selection

Answer 36

Direct competition among individuals of one sex for mates of the opposite (males fighting for a female)

Question 37

Intersexual selection

Answer 37

When individuals of one sex (usually females) are choosy in selecting their mate

Question 38

Sexual dimorphism

Answer 38

When the male and female of a species look completely different

Question 39

Heterozygote advantage

Answer 39

When heterozygotes have a higher fitness than do both homozygotes

Question 40

Example of heterozygote advantage

Answer 40

A mutation in hemoglobin causes mild sickle-cell disease, but is malaria resistant so in rainy parts of the world (more mosquitoes) more people HbA/HbS, because HbA/HbA (normal hemoglobin) = susceptible to malaria, and HbS/HbS (sickle cell anemia) = full blown sickle cell anemia