BIOL 190A > Chapter 19: Evolution > Flashcards

Chapter 19: Evolution Flashcards

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1
Q

What is evolution?

A

A change in one or more heritable characteristics of a population from one generation to the next

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2
Q

What is population?

A

The number of organisms of a species in a specific area

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3
Q

When did the modern idea of evolution begin?

A

In the late 1700s, a small number of European scientists challenged the belief that life-forms are fixed and unchanging

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4
Q

What is empirical thought?

A

The formation of an idea or hypothesis based on observation

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5
Q

What happened in the 1600s?

A

A shift towards empirical thought that encouraged scholars to rely on observation to understand life and the natural world

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6
Q

What is uniformitarianism?

A

Slow geological processes lead to substantial change over time, implying that the Earth is older than 6,000 years

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7
Q

What influenced Charles Darwin’s ideas?

A

Work in other fields and his own observations during his voyage on the Beagle

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8
Q

What did Charles Darwin observe on his journey?

A

Distinctive traits of island species that allowed them to better exploit their environment

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9
Q

What did Charles Darwin and Alfred Wallace suggest?

A

Existing species are derived from pre-existing species

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10
Q

How did Charles Darwin express his ideas about evolution?

A

Descent with modification through variation and natural selection

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11
Q

What are the two mechanisms that drive evolution?

A
  1. Genetic modification
  2. Natural selection
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12
Q

What is genetic modification?

A

Variation in traits may occur among individuals of a given species; variations are based on genetic differences and are heritable (passed from parents to offspring)

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13
Q

What is natural selection?

A

Individuals with heritable traits that make them better suited to their environment tend to flourish and reproduce, whereas other individuals are less likely to survive and reproduce

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14
Q

What is the result of natural selection?

A

Certain traits that favor reproductive success become more prevalent in a population over time

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15
Q

What are fossils?

A

The preserved remains of past lifeWhat

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16
Q

What does the fossil record show?

A

Evidence of the history of life on Earth

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17
Q

What does the fishapod (Tiktaalik roseae) show?

A

Evolutionary change; it is a transitional form

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18
Q

What is a transitional form?

A

An organism that shows its ancestors’ and descendants’ features; an intermediate form

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19
Q

What does the whale fossil record show?

A

A progression over the past 50 million years from a terrestrial tetrapod to aquatic animals that lack hind limbs and have many adaptation that are beneficial in an aquatic environment.

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20
Q

What is biogeography?

A

The study of the geographic distribution of extinct and living species

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21
Q

What are endemic species?

A

Species naturally found only in a particular location

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22
Q

What is convergent evolution?

A

When two species from different lineages have independently evolved similar characteristics because they occupy similar environments

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23
Q

What are analogous structures?

A

Similar characteristics due to convergent evolution

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24
Q

What is selective breeding?

A

Programs and procedures designed to modify traits in domesticates species

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25
What is artificial selection?
Human breeders select which individuals will reproduce based on desirable traits; humans have employed selective breeding for centuries
26
How did vegetables like kale, broccoli, and cabbage come to be?
Many vegetable crops have been developed by selective breeding of the wild mustard plant
27
What is homology?
A similarity that occurs due to descent from a common ancestor; homologies may involve anatomical, developmental, or molecular features
28
What is molecular homology?
Similarities that occur at the molecular level; the degree of similarity between genetic sequences from different species reflects the evolutionary relatedness of those species
29
What are vestigial structures?
Anatomical features that have no current function but resemble structures of presumed ancestors
30
What is anatomical homology?
Similarities between anatomical features
31
What is a developmental homology?
Similarities that occur during development
32
What are the 8 pieces of evidence to support evolution?
1. Studies of natural selection 2. Fossil record 3. Biogeography 4. Convergent evolution 5. Selective breeding 6. Anatomical homology 7. Molecular homology 8. Developmental homology
33
What is the gene pool?
All of the alleles for every gene in a population
34
What is population genetics?
Study of genetic variation within a gene pool and
35
What is adaptation?
36
What is polymorphism?
The presence of two or more variants for a given character within a population
37
What is a polymorphic gene?
Exists as two or more alleles in a population
38
What is a monomorphic gene?
Exists as only one allele in a population
39
How can genes become polymorphic?
Deletion, duplication, or change in a single nucleotide
40
What is a single-nucleotide polymorphism (SNP)?
The smallest type of genetic variation that can occur within a gene and is the most common
41
What does genetic variation show?
A large and healthy population
42
What is allele frequency?
(Number of copies of a specific allele in a population) ---------------------------------------------------------------------------- (Total number of all alleles for that gene in the population)
43
What is gene frequency?
(Number of individuals with a particular genotype in a population) ------------------------------------------------------------------------------ (Total number of individuals in the population)
44
What is needed to evaluate population genetics?
Genetic variation can be analyzed quantitatively using calculations of allele frequency and genotype frequency
45
What is the Hardy-Weinberg equation?
Describes the relationship between allele and genotype frequencies when a population is not evolving; for genes that exist in two alleles, p + q = 1
46
What does the Hardy-Weinberg equation predict?
Allele and genotype frequencies will remain the same, generation after generation, for a population in equilibrium
47
How is genotype frequency represented by the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1 p^2 = AA 2pq = Aa q^2 = aa
48
What can the allele frequency in a gamete tell us about the population?
In a population, the frequency of a gamete carrying a particular allele is equal to the allele frequency of the population
49
What are the required conditions for a population to be in Hardy-Weinberg equilibrium?
1. No new mutations 2. No natural selections (evolutionary pressure) 3. Very large population (genetic drift have little to no effect) 4. No migration occurs between different populations 5. Random mating occurs
50
What is microevolution?
Describes changes in a population's gene pool (changes in allele frequency) from generation to generation
51
Why does microevolution occur?
The introduction of new genetic variation and evolutionary mechanisms that alter the frequencies of existing genetic variation
52
What is fitness?
The relative likelihood that one genotype will contribute to the gene pool of the next generation compared with other genotypes; fitness is a measure of reproductive success
53
What is reproductive success?
The likelihood of an individual contributing fertile offspring to the next generation
54
How is fitness calculated?
The genotype with the highest reproductive success is assigned a fitness value of 1.0; fitness values of other genotypes are assigned relative to this value
55
What is reproductive success influenced by?
1. Characteristics that make organisms better adapted to their environment 2. Traits that are directly associated with reproduction
56
What are the different patterns of natural selection?
1. Directional selection 2. Balancing selection 3. Diversifying selection 4. Sexual selection
57
What is directional selection?
Favors individuals at one extreme of a phenotypic range because they have greater reproductive success in a particular environment
58
What is diversifying selection?
Favors the survival of two or more different genotypes that produce different phenotypes
59
What is balancing selection?
Maintains genetic diversity in a population
60
What is balanced polymorphism?
When 2 or more alleles are kept in balance and maintained in a population
61
What is heterozygote advantage?
When heterozygotes have the highest fitness
62
What is negative frequency-dependent selection?
Common individuals have a lower fitness, and rare individuals have a higher fitness
63
What is sexual selection?
A form of natural selection by which individuals with certain traits are more likely than others to engage in successful mating
64
What is intrasexual (within) selection?
A form of sexual selection in which members of one sex directly compete with each other for the opportunity to mate with individuals of the opposite sex
65
What is intersexual (between) selection?
A form of sexual selection in which members of one sex choose their mates on the basis of certain desirable characteristics
66
What is genetic drift?
Changes in allele frequencies due to random chance; genetic drift favors either the elimination or the fixation of an allele
67
What does allele fixation mean?
The complete inheritance of an allele
68
What does allele elimination mean?
The complete loss of an allele
69
What is a bottleneck?
A drastic reduction in size where members are eliminated without regard to their genetic composition
70
What is the bottleneck effect?
The change in allele frequencies of the resulting population due to genetic drift
71
What is the neutral theory of evolution?
Genetic drift promotes the accumulation of neutral genetic changes that do not affect reproductive success
72
What is neutral variation?
The idea that not all genetic changes are adaptive
73
What is gene flow?
74
What are mechanisms that tend to increase genetic diversity?
Migration between populations and nonrandom mating
75
What is nonrandom mating?
BIOL 190A
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