Population Genetics

Question 1

__________________ can cause
changes in allele frequency.

Answer 1

Selection, migration, and genetic drift

Question 2

_______ creates new alleles in a population gene pool.

Answer 2

Mutation

Question 3

_______ changes population genotype frequency but not allele frequency.

Answer 3

Nonrandom mating

Question 4

source of variation

Answer 4

mutation and recombination

Question 5

mechanism of inheritance

Answer 5

segregation of alleles

Question 6

a consequence of changes in genetic material through mutation and changes in allele frequencies in populations over time

Answer 6

Evolution

Question 7

union of population genetics with the theory of natural selection

Answer 7

neo-Darwinism

Question 8

the formation of new species

Answer 8

speciation

Question 9

Sources of speciation

Answer 9

Natural selection
Mutation
Migration
Drift

Question 10

______investigate patterns of genetic variation within and among groups of interbreeding individuals

Answer 10

Population geneticists

Question 11

evolutionary change within populations of a species

Changes in allele frequencies in a population that do not directly result in species formation

Answer 11

microevolution

Question 12

evolutionary events leading to the emergence of new species and other taxonomic groups

Answer 12

macroevolution

Question 13

is a group of individuals belonging to the same species that live in a defined geographic area and actually or potentially interbreed

Answer 13

population

Question 14

The genetic information carried by members of a population constitutes that population’s _____

Answer 14

gene pool

Question 15

_________ , which ran from 2008 through 2015, was a global effort to identify and catalog at least 95% of the common genetic variations carried by the 7 billion people now inhabiting the planet.

Answer 15

1000 Genomes Project

Question 16

The 1000 Genomes Project eventually sequenced the genomes of 2504 individuals from 26 populations using a combination of _____

Answer 16

1. whole-genome sequencing at low coverage levels
2. exome sequencing
3. microarray genotyping.

Question 17

mutations leading to amino acid substitutions are usually detrimental, with only a very small fraction being favorable

Answer 17

neutral theory of molecular evolution

Some mutations are neutral; that is, they are functionally equivalent to the allele they replace

Question 18

Mutations that are favorable or detrimental are preserved or removed from the population, respectively, by natural selection. However, the frequency of the neutral alleles in a population will be determined by mutation rates and random genetic drift, and not by selection.

Question 19

The neutral theory nonetheless serves a crucial
function:

Answer 19

It points out that some genetic variation is expected simply as a result of mutation and drift.

Question 20

describes what happens to allele and genotype frequencies in an “ideal” population that is infinitely large and randomly mating and that is not subject to any evolutionary forces such as mutation, migration, or selection

model that shows the relationship between the relative proportions of alleles in the gene pool and the frequencies of different genotypes in the population

Answer 20

Hardy–Weinberg law

Question 21

the distribution of genotypes among the zygotes is…

Answer 21

p^2 + 2pq + q^2 = 1

Question 22

two main predictions of the Hardy-Weinberg model:

Answer 22

1. Allele frequencies in our population do not change from one generation to the next.
2. After one generation of random mating, genotype frequencies can be predicted from the allele frequencies.

Question 23

The theoretical population described by the Hardy–Weinberg model is based on the following assumptions:

Answer 23

1. Equal survival rates of offspring.
2. Absence of selection and mutation.
3. Lack of migration.
4. Large population size.
5. Random mating.

Question 24

Hardy–Weinberg model can be used to identify the real-world forces that cause allele frequencies to change

Question 25

The Hardy–Weinberg model has three additional important consequences:

Answer 25

1. Dominant traits do not necessarily increase from one generation to the next. 2. Genetic variability can be maintained in a population, since, once established in an ideal population, allele frequencies remain unchanged. 3. Under Hardy–Weinberg assumptions, knowing the frequency of just one genotype enables us to calculate the frequencies of all other genotypes at that locus.

Question 26

A small number of individuals who make high-risk choices (such as having unprotected sex with HIV positive partners) never become infected. Some of these individuals are homozygous for a mutant allele of a gene called _______

Answer 26

CCR5 - encodes a protein called the C-C chemokine receptor-5 (CCR5)

Question 27

______ are cell surface signaling molecules associated with the immune system.

Answer 27

Chemokines

Question 28

in which chromosome is CCR5 gene found

Answer 28

Chromosome 3

Question 29

how does the HIV-1 infection resistance in CCR5 gene

Answer 29

32-bp deletion in exon 4 that confers resistance to HIv-1 infection

Question 30

Hardy-Weinberg formula for 3 alleles

Answer 30

p^2 + q^2 + r^2 + 2pq + 2pr + 2qr = 1

Question 31

_______ occurs whenever individuals with a particular genotype enjoy an advantage in survival or reproduction over other genotypes

Answer 31

Selection

Question 32

An individual organism’s genetic contribution to future generations is called its _____

Answer 32

fitness (𝑤)

Question 33

Types of Selection

Answer 33

1. Directional 2. Stabilizing 3. Disruptive

Question 34

traits at one end of a spectrum of phenotypes present in the population become selected for or against, usually as a result of changes in the environment.

Answer 34

directional selection

Question 35

selects for intermediate phenotypes, with those at both extremes being selected against. Over time, this will reduce the phenotypic variance in the population but without a significant shift in the mean.

Answer 35

Stabilizing selection

Question 36

is selection against intermediate phenotypes and selection for phenotypes at both extremes

Answer 36

Disruptive selection

Question 37

A reduction in gene flow between populations, accompanied by selection or genetic drift, can lead to reproductive isolation and speciation.

Question 38

assortment and recombination do not produce new alleles.

Question 39

Mutation - Creates new alleles but has a slow impact on allele frequencies unless the population is small.

Question 40

mutation rate m for achondroplasia

Answer 40

μ = 1.4 x 10^-5 +- 0.5 x 10^-5

Question 42

occurs when individuals move between populations

Answer 42

migration

Question 43

In small populations, significant random fluctuations in allele frequencies are possible by chance alone, a situation known as ______

Answer 43

genetic drift

Question 44

occurs when a population originates from a small number of individuals

Answer 44

founder effect

Question 45

develop when a large population undergoes a drastic but temporary reduction in numbers

Answer 45

Genetic bottleneck

Question 46

_________, similar genotypes are more likely to mate than dissimilar ones.

Answer 46

positive assortative mating

Question 47

______ occurs when dissimilar genotypes are more likely to mate

Answer 47

Negative assortative mating

Question 48

______ occurs when mating individuals are more closely related than any two individuals drawn from the population at random; loosely defined, it is mating among relatives.

Answer 48

Inbreeding

Question 49

This coefficient quantifies the probability that the two alleles of a given gene present in an individual are identical because they are descended from the same single copy of the allele in an ancestor.

Answer 49

coefficient of inbreeding (F) If F = 1, all individuals in the population are homozygous, and both alleles in every individual are derived from the same ancestral copy. If F = 0, no individual has two alleles derived from a common ancestral copy.

Question 50

As the level of inbreeding increases, the frequency of heterozygotes declines.

Question 51

a group of actually or potentially interbreeding organisms that is reproductively isolated in nature from all other such groups.

Answer 51

Species

Question 52

a period with no change

Answer 52

stasis

Question 53

an evolutionary process where a species evolves gradually while continuing to exist as an interbreeding population

Answer 53

Anagenesis

Question 54

an evolutionary process where a parent species splits into two or more descendant species, forming a clade

Answer 54

Cladogenesis

Question 55

The biological barriers that prevent or reduce interbreeding between populations are called...

Answer 55

reproductive isolating mechanisms

Question 56

reproductive isolating mechanisms

Answer 56

1. Geographic or ecological - The populations live in the same regions but occupy different habitats. 2. Behavioral - (Only in animals.) The populations are isolated by different and incompatible behavior before mating. 3. Seasonal or temporal - The populations live in the same regions but are sexually mature at different times. 4. Mechanical - Cross-fertilization is prevented or restricted by differences in reproductive structures 5. Physiological - Gametes fail to survive in alien reproductive tracts.

Question 57

________ prevent individuals from mating in the first place.

Answer 57

Prezygotic isolating mechanisms

Question 58

_____ create reproductive isolation even when the members of two populations are willing and able to mate with each other

Answer 58

Postzygotic isolating mechanisms

Question 59

In animal evolution, one of the most effective prezygotic mechanisms is ______, involving courtship behavior.

Answer 59

behavioral isolation

Question 60

Postzygotic Mechanisms: Fertilization takes place and hybrid zygotes are formed, but these are nonviable or give rise to weak or sterile hybrids.

Answer 60

1. Hybrid nonviability or weakness. 2. Developmental hybrid sterility. Hybrids are sterile because gonads develop abnormally or meiosis breaks down before completion. 3. Segregational hybrid sterility. Hybrids are sterile because of abnormal segregation into gametes of whole chromosomes, chromosome segments, or combinations of genes.

Question 61

the average time for speciation ranges from _____ years

Answer 61

100,000 to 10,000,000 years

Question 62

(of a group of organisms) descended from a common evolutionary ancestor or ancestral group

Answer 62

monophyletic

Question 63

show the ancestral relationships among a group of organisms branches represent the relationships among lineages over time. The length of a branch can be derived from a time scale. Nodes, show when a species split into two or more species. Each node represents a common ancestor of the species diverging at that node. The root of a phylogenetic tree represents the oldest common ancestor to all the groups shown in the tree.

Answer 63

Phylogenetic trees

Question 64

Groups that consist of an ancestral species and all its descendants are called ______

Answer 64

monophyletic groups

Question 65

Constructing a species-level phylogenetic tree using DNA sequences involves three steps:

Answer 65

1. DNA sequences representing a gene or genome of interest from a number of different species must be acquired. - available from public databases 2. The sequences must be aligned with each other so that the related parts of each sequence can be compared to see if they are the same or different - can be imported into software programs that maximize the number of aligned base pairs by inserting gaps as needed 3. These DNA differences are used to construct a phylogenetic tree, often beginning with the most closely related sequences and working backward through sequences that are less closely related

Question 66

the closest living relative to terrestrial vertebrates, _______

Answer 66

lungfish

Question 67

use the rate of change in amino acid or nucleotide sequences as a way to estimate the time of divergence from a common ancestor.

Answer 67

molecular clocks

Question 68

the study of ancient DNA to reconstruct and analyze the genomes of organisms that are no longer alive

Answer 68

paleogenomics

Question 69

________________—a species that became the ancestor to our species

Answer 69

H. heidelbergensis

Question 70

out-of-Africa hypothesis - H. sapiens evolved from the descendants of H. heidelbergensis in Africa about 300,000 years ago.

Question 71

the group of cells in a multicellular organism that develop into germ cells

Answer 71

germline

Question 72

branch of genetics which deals with the behavior of genes at the population level the study of polymorphism and divergence

Answer 72

population genetics

Question 73

multiple forms of a trait within a species

Answer 73

polymorphism

Question 74

local interbreeding units; also called local populations, Mendelian populations or demes

Answer 74

subpopulation

Question 75

Number of times an allele occurs in a gene pool, compared to the total number of alleles for that gene

Answer 75

Allele frequency

Question 76

Populations, not individuals, evolve

Question 77

Why is genetic variation important?

Answer 77

it allows populations to adapt and survive in changing environments and it's the raw material for evolution

Question 78

How does genetic structure change?

Answer 78

Mutation Genetic drift Gene flow (migration) Nonrandom mating Natural selection

Question 79

Mdh-1alleles in snail colonies

Answer 79

Malate dehydrogenase (enzyme crucial for energy production in cells) Krebs cycle

Question 80

Lap locus in prairie vole populations

Answer 80

encodes the enzyme leucine aminopeptidase, plays a significant role in protein metabolism

Question 81

adaptation to environmental chang

Answer 81

conervation

Question 82

divergence of populations

Answer 82

biodiversity

Question 83

Mechanisms of variation

Answer 83

Mutation Sexual reproduction Gene flow

Question 84

Mechanisms of change

Answer 84

Genetic drift Natural selection

Question 85

different molecular forms of an enzyme that correspond to different alleles of a common gene (locus)

Answer 85

Allozyme

Question 87

Signaling molecules used by the immune system

Answer 87

Chemokines

Question 88

Virus that attacks cells that help the body fight infection

Answer 88

HIV

Question 89

Gene pool equation

Answer 89

p + q = 1

Question 90

Genetic change by chance alone

Answer 90

Genetic drift

Question 91

All individuals are potential partners for reproduction and mating occurs randomly

Answer 91

Panmictic population