Unit 7: Evolution and Natural Selection

Question 1

Define

Evolution

Answer 1

A change to a population’s gene pool

Question 2

Compare

Microevolution & Macroevolution

Answer 2

Microevolution: Small scale; on the level of populations

Macroevolution: Large scale; on the level of whole-species

Question 3

Define

Genetic equilibrium

Answer 3

No changes to allele frequencies and/or distribution of a population’s phenotypes

Question 4

Define

Gene pool

Answer 4

All versions of the genes from all members of a population that are capable of reproducing

Question 5

Define

Allele Frequency

Answer 5

Prevalence of a certain allele within a gene pool

Question 6

List

Five conditions for Hardy-Weinberg Equilibrium

Answer 6

Population is/has:

- infinitely large

- no mutations

- no migration

- random mating

- all alleles equally likely to be passed into subsequent generation

Question 7

In terms of Hardy-Weinberg, what happens if:

population is small

Answer 7

Genetic drift may occur

Question 8

In terms of Hardy-Weinberg, what happens if:

mutations occur

Answer 8

new alleles affect overall allele frequencies AND may increase chances of other conditions of H-W

Question 9

In terms of Hardy-Weinberg, what happens if:

populations mix / migration occurs

Answer 9

New alleles may be introduced into population

Question 10

In terms of Hardy-Weinberg, what happens if:

sexual selection occurs

Answer 10

individuals with preferred phenotypes are more likely to pass on their alleles

Question 11

In terms of Hardy-Weinberg, what happens if:

natural selection occurs

Answer 11

favorable alleles/traits have increased allele frequencies

Question 12

Define

Genetic drift

Answer 12

Random fluctuations in allele frequencies in a population

Question 13

List two common types of

Genetic drift

Answer 13

Bottleneck Effect

and

Founder Effect

Question 14

Describe

The Bottleneck Effect

Answer 14

Random decrease in population size, which changes allele frequencies purely due to chance

Question 15

Describe

The Founder Effect

Answer 15

Migration of part of a population, whose allele frequencies do not reflect the population as a whole

Both the original population and new population have different allele frequencies from the original

Question 16

In Hardy-Weinberg Equation:

What do the terms p and q refer to?

Answer 16

Allele frequencies of two alleles in a population

Reminder: All individuals carry two copies of all autosomal genes, therefore

(total # of alleles) = (population size) X 2

Question 17

In Hardy-Weinberg Equation:

What does the term 2pq refer to?

Answer 17

The expected frequency of individuals in a population that are heterozygous

Question 18

In Hardy-Weinberg Equation:

What does the term q² refer to?

Answer 18

The expected frequency of individuals in a population that are homozygous for the recessive allele

Question 19

In Hardy-Weinberg Equation:

What does the term p² refer to?

Answer 19

The expected frequency of individuals in a population that are homozygous for the dominant allele

Question 20

Define

Selection

Answer 20

Any phenomenon that preferentially leads to higher fitness in one allele over another

Question 21

Define

Fitness

Answer 21

Reproductive success

Question 22

List

Conditions necessary for natural selection

Answer 22

- The population must have heritable variations

- Some of those variations convey a selective advantage

- Competition or other factors limit population size

Question 23

Define

Adaptation

Answer 23

A variant for a particular trait that allows individuals with that variant to survive and reproduce more than those without the variant

Question 24

Define

Adapt

Answer 24

The process where a population / species becomes better-suited to survive and reproduce in their environment

Question 25

List and define

The two types of characters

Answer 25

Discrete: Controlled by one or a few genes, producing a finite number of phenotypes

Quantitative: Controlled by many genes (polygenic) and influenced by environment, producing a range of phenotypes

Question 26

How is evolution measured for each character?

Answer 26

Discrete: Change in allele frequencies

Quantitative: Changes in distribution of phenotypes

Question 27

List

Three types of selection in quantitative characters

Answer 27

- Directional

- Stabilizing

- Disruptive

Question 28

Define

Artificial selection

Answer 28

Humans are the selective pressure; desired or useful traits are selected for

AKA “Breeding”

Question 29

List examples of

Artificial selection

Answer 29

Crops with highest sugar content, most starch, least chewy, and/or various pest or weather resistances are cultivated and become most common

Farm animals that produce the most milk, eggs, and/or meat are bred most

Dogs have been domesticated into separate breeds, each by artificial selection

Question 30

What is the source of all genetic variation in a population?

Answer 30

Mutation

Question 31

How does sexual reproduction affect genetic variability?

Answer 31

Increases it by mixing existing alleles (originally from mutations) during meiosis (crossing over, random assortment) and fertilization