Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology II > The Evolution of Populations > Flashcards

The Evolution of Populations Flashcards

Chapter 19 of the book

1
Q

What do scientists consider a key concept to understanding life?

A

Evolution

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

What does Natural Selection promote? What does it eliminate?

A

It promotes traits and behaviors that increase an organism’s chance of survival and reproduction.
It eliminates traits and behaviors that are detrimental to an organism.

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

Does Natural Selection create or select?

A

It selects, as the name implies, and CANNOT create.
It acts on the population’s heritable traits.

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

What is Modern Synthesis?

A

The integration of genetics and evolution; the coherent understanding of the relationship b/w natural selection & genetics.

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

What does Modern Synthesis describe?

A

How evolutionary processes, such as natural selection, can affect a population’s genetic makeup, & how this can result in the gradual evolution of populations & species. Also connects the pop. change over time.

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

What is Microevolution?

A

Changes in a population’s genetic structure.

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

What is Macroevolution?

A

Broader scale evolutionary changes that scientists see over paleontological time.

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

Can a gene for a particular character have several alleles that code for different traits associated with that character?

A

Yes

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

What is Population Genetics?

A

Study of how selective forces change the allele frequencies in a pop. over time

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

What is Allele Frequency?

A

A.K.A gene frequency is the rate at which a specific Allele appears within a pop.

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

How can allele frequency within a given pop. change?

A

Environmental Factors

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

How can Natural Selection alter the population’s genetic makeup?

A

By allowing certain alleles to become more widespread than others during the process.

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

What is a Gene Pool?

A

The sum of all the alleles in a pop.

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

What phenomenon can sometimes cause allele frequencies within a pop. to change randomly w/no advantage to the pop. over existing allele frequencies?

A

Genetic Drift

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

What 2 events occur simultaneously in populations?

A
  1. Natural Selection
  2. Genetic Drift
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the Founder Effect?

A

An event that initiates an allele frequency change in an isolated part of the pop., which is not typical of the original pop.

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

What 3 mechanisms can lead to significant changes in a population’s genome?

A
  1. Natural Selection
  2. Random Drift
  3. Founder Effect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does the Hardy-Weinberg principle of equilibrium state?

A

That a population’s allele & genotype frequencies are inherently stable — unless some kind of evolutionary force is acting open the pop., neither the allele nor the genotypic frequencies would change.

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

What conditions does the Hardy-Weinberg principle assume?

A
  1. No mutations
  2. No migration or immigration
  3. No selective pressure for or against a genotype (Natural Selection)
  4. Infinite Population
  5. Random Mating
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is Genetic Structure?

A

Distribution of the different possible genotypes in a pop.

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

What would occur if a pop. is at equilibrium for the Hardy-Weinberg principle?

A

The equations would hold to be true all the time b/c generation after generation the gene pool & genetic structure would still remain the same.

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

What is polymorphisms?

A

A population’s individuals displaying different phenotypes or different alleles of a particular gene.

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

What is polymorphic?

A

Populations with 2 or more variations of particular characteristics.

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

What is Population Variation?

A

The distribution of phenotypes among individuals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
The greater Heritability of a population's phenotypic variation, the ....
more susceptible it is to the evolutionary forces that act on heritabile variation.
25
What is Heritability?
The fraction of phenotype variation that we can attribute to genetic differences, or genetic variance, among individuals in a pop.
26
What is Genetic Variance?
Diversity of alleles & genotypes in a pop.
27
What is Inbreeding?
The mating of closely related individuals, which can have the undesirable effect of bringing together deleterious recessive mutations that can cause abnormalities & susceptibility to disease.
28
What is Inbreeding Depression?
Increase in abnormalities & disease in Inbreeding populations.
29
What is Genetic Drift?
The effect of chance. By chance, some individuals will have more offspring that others --- not due to an advantage conferred by some genetically -encoded trait, but b/c one male happened to be in the right place at the right time OR because the other one happened to be in the wrong place at the wrong time. This is another way a population's allele & genotype frequencies can change.
30
Who are more susceptible to forces of genetic drift?
Small populations, while large populations are buffered against the effects of chance.
31
What is the Bottleneck Effect?
Magnification of genetic drift as a result of natural events or catastrophes. Example: A random earthquake occurs that kills a large portion of the population, resulting in a sudden wipe out of a large portion of the genome. At once the survivors' genetic structure becomes the entire population's genetic structure.
32
What is the Founder Effect?
A portion of the pop. leaves to start a new pop. in a new location OR a physical barrier may occur that divides the pop. This occurs when the genetic structure changes to match that of the NEW population's FOUNDING father or mother.
33
What is Gene Flow?
The flow of alleles in & out of a pop. due to the migration of individuals or gametes.
34
What changes occur with variable flow of individuals in & out of a group?
1. Population gene structure 2. Introduction of new genetic variation to the pop. in different geological locations & habitats.
35
What is a mutation?
A change to an organism's DNA & are important drivers of diversity in a pop.
36
How do species evolve because of mutations?
By mutations accumulating over time. Some mutations are unfavorable/harmful & are quickly eliminated from the pop. by natural selection. Others are beneficial & spread through the pop. Some mutations do not do anything & can linger, unaffected by natural selection, in the genome. Some can have a dramatic effect on a gene & the resulting phenotype.
37
How is a mutation determined whether or not to be harmful or beneficial?
By whether it helps an organism survive to sexual maturity & reproduce.
38
What is Nonrandom Mating?
Changes in a population's gene pool due to mate choice or other forces that cause individuals to mate with certain phenotypes more than others
39
Why does nonrandom mating occur?
1. Mate choice 2. Physical location
40
What is Assortative Mating?
An individual's preference to mate with partners who are phenotypically similar to themselves.
41
Can the environment influence phenotypes?
Yes, for example, geographic separation b/w populations can lead to differences in the phenotypic variation b/w those populations.
42
What is Geographical Variation?
Differences in the phenotypic variation b/w populations that are separated
43
What is a Cline?
Gradual geographic variation across an ecological gradient. Example: Species of warm-blooded animals tend to have larger bodies in the cooler climates closer to the earth's poles, allowing them to better conserve heat.
44
What is Adaptive Evolution?
Increase in frequency of beneficial alleles & decrease in deleterious alleles due to selection.
45
What does Natural Selection act on?
The entire organism, NOT on an individual allele within the organism. At the individual's level.
46
What is Evolutionary (Darwinian) Fitness?
Individual's ability to survive & reproduce.
47
What is Relative Fitness?
Individual's ability to survive & reproduce relative to the rest of the pop.
48
What are the ways selection can affect population variation?
1. Stabilizing Selection 2. Directional Selection 3. Diversifying Selection 4. Frequency-Dependent Selection 5. Sexual Selection
49
What occurs when natural selection influences the allele frequencies in a pop.?
Individuals can either become more or less genetically similar & the phenotypes can become more similar or more disparate.
50
What is Stabilizing Selection?
Selection that favors average phenotypes, selecting against extreme variation. Resulting in a population's genetic variance decreasing
51
What is Directional Selection?
Selection that favors phenotypes at one end of the spectrum of existing variation. Resulting in a shift in the population's genetic variance toward the new, fit phenotype.
52
What is Diversifying Selection?
Selection that favors 2 or more distinct phenotypes. Can occur when environmental changes favor individuals on either end of the phenotypic spectrum. Resulting in increased genetic variance as the pop. becomes more diverse.
53
What is Frequency-Dependent Selection?
Selection that favors phenotypes that are either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection). Negative frequency-dependent selection serves to increase the population's genetic variance by selecting for rare phenotypes. Positive frequency-dependent selection usually decreases genetic variance by selecting for common phenotypes.
54
What is Sexual Dimorphism?
Phenotypic difference b/w a population's males & females.
55
What is the Handicap Principle?
Theory of sexual selection that argues only the fittest individuals can afford costly traits
56
What is the Good Gene Hypothesis?
Theory of sexual Selection that argues individuals develop impressive ornaments to show off their efficient metabolism or ability to fight disease.
57
What is Honest Signal?
Trait that gives a truthful impression of an individual's fitness.
58
Does Natural Selection produce the perfect organism?
No
59
Is natural selection limited?
Yes, b/c it works at the individual level, not allele level, & some alleles are linked due to their physical proximity in the genome, making them more likely to pass on together (linkage disequilibrium). Also natural selection can be constrained by the relationship b/w different polymorphisms. One morph may confer a higher fitness than another, but may not increase in frequency b/c going from the less beneficial to the more beneficial trait would require going through a less beneficial phenotype.
60
Are all evolution adaptive?
No

Biology II (7 decks)

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