Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology 1407 > Chapter 23 Evolution of Populations > Flashcards

Chapter 23 Evolution of Populations Flashcards

(75 cards)

Start Studying
1
Q

Do organisms evolve during their lifetimes?

A

No, only natural selection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does natural selection act on?

A

Genetic variation, different phenotypes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Can populations evolve?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

*there must be a change in ___________ for evolution to take place

A

Allele frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a change in allele frequency‘s in a population over generations?

A

Microevolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In microevolution what are the three mechanisms that cause allele frequency change?

A

-natural selection -genetic drift -Gene flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Only ___________ causes adaptive evolution

A

Natural selection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the mechanism that improves the match between the organism and its environment?

A

Natural selection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the mechanism that can cause a change in the gene pool of a small population strictly by chance?

A

Genetic drift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The transfer of genetic variation from one population to another coming or leaving the population

A

Gene flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a prerequisite for evolution?

A

Genetic variation in heritable traits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Genetic variation among individuals is caused by ____________.

A

Differences in genes or other DNA segments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What contributes to phenotypic differences?

A

Single gene or Two or more genes (quantitative characters)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Average heterozygosity measures the average percent of loci that are heterogeneous in a population

A

Gene variability *more valuable measurement compared to nucleotide variability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Measured by comparing the DNA sequence of pairs of individuals

A

Nucleotide variability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do you new genes and alleles arise?

A

-mutation -gene duplication -exon shuffling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are other sources of genetic variation?

A

-horizontal gene transfer -sexual reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

-a change in nucleotide sequence of DNA

A

Mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Only mutations in cells that produce ________ can be passed offspring

A

Gametes (egg or sperm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a change in one base in a gene?

A

Point mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why can mutations to genes be neutral?

A

No change to the amino acid being made, it’s silent no change in the phenotype Or mutations that occur in the introns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

differences in DNA sequence that do not confer a selective advantage or disadvantage Ex: mutations in non-coding regions of DNA

A

Neutral variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Duplicated genes can take on new __________ by further mutation Ex. Globins (hemoglobin, myoglobin)

A

Functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Are mutation rates higher or lower in animals and plants? With a Mutation rate of…

A

Low 1 in every 100,000 genes per generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Mutations rates are often ________ in prokaryotes and ________ in viruses
Lower, higher
26
Why do most mutations accumulate quickly in prokaryotes in viruses?
Shorter lifespan (20-30 min)
27
sexual reproduction can shuffle existing alleles into new combinations by what three ways?
-crossing over -independent assortment of chromosomes -fertilization
28
In organisms that reproduce sexually, _________ of alleles is more important than mutations in producing the genetic differences that make adaptation possible
Recombination
29
What equation is used to test whether a population is evolving?
Hardy-Weinberg Equation P^2 + 2pq + q^2 = 1
30
p= q= p^2= 2pq= q^2=
p= frequency of dominant allele q= frequency of recessive allele p^2= Frequency of AA genotype 2pq= frequency of Aa genotype q^2= Frequency of aa genotype
31
A localized group of individuals capable of interbreeding and producing fertile offspring
Population
32
Consists of all the alleles for all loci in a population
Gene pool
33
The Hardy-Weinberg principle describes a population that is.....
Not evolving
34
If a population does not meet the criteria of the Hardy-Weinberg principle, it can be concluded that the population is \_\_\_\_\_\_\_\_\_\_
Evolving
35
Principle that states frequencies of alleles and genotypes in a population remain constant from generation to generation
The Hardy-Weinberg principle
36
Describes the constant frequency of alleles in a gene pool
Hardy-Weinberg equilibrium
37
Describes a hypothetical population that is not evolving
The Hardy-Weinberg theorem
38
\*\*\* in the Hardy-Weinberg theorem what are the five conditions for non-evolving populations (rarely met in nature)
1. No mutations 2. Random mating 3. No natural selection 4. Extremely large population size 5. No gene flow
39
Natural populations can evolve at some loci, while being in Hardy-Weinberg equilibrium at other loci. True or false?
True
40
Phenylketonuria (PKU) that occurs 1 in every 10,000 births (2% of the U.S. population) is an example of ....
Hardy-Weinberg equilibrium
41
What are the three major factors that alter allele frequencies and bring about most evolutionary change?
-natural selection -genetic drift -Gene flow
42
How does natural selection alter allele frequency?
Differential success in reproduction results in certain alleles being passed to the next generation in greater proportions
43
How does genetic drift alter allele frequency?
-changes Clearlake frequency due to random chance -describes how allele frequency‘s fluctuate unpredictably from one generation to the next
44
Will a smaller or larger sample have a greater chance of deviation from a predicted result?
Smaller
45
How does genetic drift tend to reduce genetic variation?
-
46
What effect can be seen when a few individuals become isolated from a larger population? Can allele frequencies in this smaller population be different from those in the larger parent population?
The founder effect Yes, does not match the parent population
47
What effect is seen when there is a sudden reduction in population size due to a change in the environment?
The bottleneck effect
48
With the bottleneck effect, is the resulting gene pool reflective of the original populations gene pool?
No. There is less genetic variation than the original population. If the population remain small, it may be further affected by genetic drift
49
-population reduced dramatically and then rebuilds -randomly eliminated members without regard to genotype -surviving members may have allele frequencies different from original population -Allele frequencies can drift substantially when the population is small -New population likely to have less genetic variation
Bottleneck effect
50
Understanding the _________ effect can increase understanding of how human activity affects other species
Bottleneck
51
Genetic drift is significant in ________ populations Genetic drift causes allele frequencies to change at \_\_\_\_\_\_\_\_\_\_
Small Random
52
Genetic drift can lead to a loss of genetic _________ within populations Genetic drift can cause harmful alleles to become \_\_\_\_\_\_\_\_\_\_
variation Fixed
53
Consists of the movement of alleles among populations Alleles can be transferred through the movement of fertile individuals or gametes (for example, pollen)
Gene flow
54
\* Gene flow tends to _______ variation among populations over time \* tends to ________ genetic diversity within a population
Reduce Enhance
55
Can gene flow decrease the fitness of a population?
It increases the fitness of the population
56
Gene flow can __________ the fitness of a population
Increase Ex: resistance to insecticide can be passed to other populations and increase their fitness
57
\_\_\_\_\_\_\_\_\_\_\_\_ is an important agent of evolutionary change in human populations
Gene flow
58
\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is the only mechanism that consistently causes adaptive evolution
Natural selection
59
In Evolution by natural selection.... New genetic variations arise by ________ Beneficial alleles are “\_\_\_\_\_\_\_” and favored by natural selection
Chance Sorted
60
Leaving genes for the next generation The contribution of an individual makes to the gene pool for the next generation, relative to the contributions of other individuals
Relative fitness
61
Selection favors certain genotypes by acting on what of individuals?
Phenotypes
62
What are the three modes of selection?
-directional selection -destructive selection -stabilizing selection
63
A mode of selection that favors individuals at one end of the phenotypic range (an extreme is picked)
Directional selection
64
Selection that favors individuals at both extremes of the phenotypic range
Disruptive selection
65
Mode of selection that favors intermediate variance and acts against extreme phenotypes
Stabilizing selection
66
Does genetic drift and gene flow consistently lead to adaptive evolution?
No. They can increase or decrease the match between the organism and it’s environment
67
natural selection for mating success
Sexual selection This can cause sexual dimorphism
68
the differences in secondary sexual characteristics between males and females of the same species
Sexual dimorphism
69
Selection within the same sex, individuals of one sex compete directly for mates of the opposite sex.
Intrasexual selection
70
Also called mate choice, one sex is choosy in selecting their mates from the other sex
Intersexual selection
71
Balancing selection includes...
-heterozygote advantage (ex: malaria protection in heterozygous for sickle cell) -frequency-dependent selection
72
Occurs when natural selection maintain stable frequencies of two or more phenotypic forms in a population
Balancing selection
73
-occurs when heterozygotes have a higher fitness then do both homozygotes -natural selection will tend to maintain two or more alleles at that locus -can result from stabilizing or directional selection
Heterozygote advantage
74
The fitness of a phenotype declines if it becomes too common in the population Selection can favor which ever phenotype is less common in a population Selects for approximately equal numbers Ex: right-mouth and left-mouth fish
Frequency-dependent selection
75
Genetic variation that does not confer a selective advantage or disadvantage
Neutral variation

Biology 1407 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions