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Evolution Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Evolution

A
  • is the gradual development and
    change of heritable traits (allele frequencies) in
    populations over successive generations.
    Evolution increases biodiversity.
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2
Q

Evidence of Evolution include

A

1) Paleontology
2) Biogeographic
3) embryology
4) Comparative Anatomy
5) Biochemical

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3
Q

Evidence of Evolution: Paleontology

A
  • is the study of fossils through actual remains of the animal or their traces
    (ichnofossils). Petrification is the process by which living organisms turn into fossils. These fossils allow us to see the development of species through time by comparing deepest (oldest) fossils to shallowest (youngest).
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4
Q

Evidence of Evolution: Biogeographic

A
  • biogeographic evidence, we can
    see the spread of different species around
    the world and analyze similarities and
    differences.
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5
Q

Evidence of Evolution: embryology

A
  • allows us to see embryological
    similarities and differences between early
    stages of related organisms. Eg. all chordates
    have a gill slit during development.
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6
Q

Evidence of Evolution: Comparative Anatomy

A
  • compares different body parts of different animals. Includes: 1) homologous structure, 2) analogous structure, and 3) vestigial structure
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7
Q

Evidence of Evolution: Biochemical

A
  • allow for DNA sequence comparisons. Can see conserved
    DNA sequences (higher similarity = higher relatedness) and common conserved pathways (eg. Krebs cycle). .
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8
Q

Homologous structures

A
  • may or may not perform the same function but have a
    common ancestor. eg. forearm of bird and
    forearm of human.
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9
Q

Analogous structures:

A
  • same function, do not have a common ancestor. eg. bird
    wings and bat wings.
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10
Q

Vestigial structures:

A
  • serve no purpose but are homologous to functional structures in other organisms eg. human appendix and cow cecum.
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11
Q

Theory of evolution

A

1) Cuvier’s catastrophism
2) Lamark’s inheritance of acquired traits
3) Darwin’s Natural Selection

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12
Q

Cuvier’s catastrophism

A
  • lead to mass extinctions of species in those areas. The different
    populations in different areas were shaped by what catastrophes had occurred, and what random organisms then survived and populated that area.
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13
Q

Lamark’s inheritance of acquired traits

A

● Use and disuse: used body parts will develop and unused ones are weakened, leading to evolution.
● Inheritance of acquired traits: traits acquired through use and disuse are
passed onto offspring (eg. giraffe stretching neck will cause its neck to
develop, and produce long necked offspring). This is incorrect - acquired
characteristics are generally not heritable.

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14
Q

Darwin - Theory of Natural Selection.

A
  • is the gradual, non-random process where allele frequencies change as a
    result of environmental interaction. Survival of the fittest occurs as individuals with greatest fitness (ability to survive and produce viable and fertile offspring) have greatest success, and pass on more DNA to future generations compared to less fit parents. Leads to the evolution of the population (not individuals).
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15
Q

Requirements for Natural Selection

A

1) Demand > supply
2) Difference in level of fitness
3) Variations in traits due to genetic influence
4) variation in traits due to reproduction and/or survival

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16
Q

Requirements for Natural Selection: Demand > supply

A
  • results in competition for survival (fittest
    survive to pass on genes).
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17
Q

Requirements for Natural Selection: Difference in level of fitness

A
  • differentiate ability to compete and
    survive (eg. black peppered moths favored
    over white moths during Industrial
    Revolution).
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18
Q

Requirements for Natural Selection: Variations in traits due to genetic influence

A
  • Variation in traits must be genetically-influenced (heritable) to be passed onto offspring.
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19
Q

Requirements for Natural Selection: variation in traits due to reproduction and/or survival

A
  • Variation in traits must be significant for
    reproduction and/or survival: genes
    improving reproductive success/survival are
    favored and increase over generations and
    vice versa.
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20
Q

Types of Natural Selection include:

A

1) Stabilizing Selection
2) Directional Selection
3) Disruptive Selection

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21
Q

Stabilizing Selection

A
  • mainstream (average) is favored (eg. birth weight). Diagram follows
    a standard bell curve.
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22
Q

Directional Selection

A
  • one extreme favored (eg. longest giraffe neck allows access to the
    most leaves).
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23
Q

Disruptive Selection

A
  • : rare traits favored, mainstream is not. (eg. snails living in low
    and high vegetation areas).
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24
Q

Other types of Selection

A

1) Sexual Selection
2) Artificial Selection

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25
Q

Sexual Selection

A
  • non-random mating between males and females. Females favor high quality partners, males prefer high quantity of partners to increase their number of offspring. Traits selected for may be favorable for reproduction
    but not for survival.
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26
Q

Artificial Selection

A
  • carried out by humans to selectively breed for specific traits (eg. dog
    breeding).
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27
Q

Gene Equilibrium: No evolution

A
  • The Hardy-Weinberg formula calculates genetic
    frequency during genetic equilibrium (no
    change in gene frequencies). If both equations
    hold true, the population is under
    Hardy-Weinberg equilibrium.

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

p= freq. of dominant allele
q= freq. of recessive allele
P^2 = freq of homozygous dominant
2pq = freq of heterozygous
q^2 = freq of homozygous recessive

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28
Q

The requirements for Hardy-Weinberg
equilibrium are:

A
  • (Mnemonic: Large, Random, M&M)
    ● Large population: minimizes genetic drift.
    ● Random mating
    ● No mutation
    ● No natural selection
    ● No migration (gene flow): population must
    be isolated.
    When conditions are not met, evolution occurs.
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29
Q

Microevolution

A
  • is the process when gene
    frequencies change within a population over
    generations (favorable genes increase,
    unfavorable decrease).
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30
Q

Factors causing Microevolution:

A

1) Genetic drift
2) non-random mating
3) mutations
4) natural selection
5) gene flow

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31
Q

Microevolution: Genetic Drift

A
  • allele frequencies change by chance. Larger effects on small populations. Includes: 1) Bottleneck effect and 2) founder effect
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32
Q

● Bottleneck effect

A
  • smaller gene pool, some alleles may be lost (eg. disaster
    killing majority of population).
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33
Q

● Founder effect

A
  • some individuals migrate away from the population.
34
Q

Microevolution: Non-random Mating

A
  • sexual selection, outbreeding, inbreeding.
35
Q

Microevolution: Mutations

A
  • can be dormant until environmental change allows it to flourish.
36
Q

Microevolution: Natural Selection

A
  • no luck involved
37
Q

Microevolution: Gene Flow

A
  • migration (non-random) moving
    alleles between populations, leading to
    variation through mixing.
38
Q

Sources of Gene Variation

A

1) Mutation
2) sexual reproduction
3) balanced polymorphism
4) polyploidy

39
Q

Sources of Gene Variation: Mutation

A
  • must not be fatal.
40
Q

Sources of Gene Variation: Sexual reproduction

A
  • crossing over, independent assortment and random joining
    of gametes.
41
Q

Sources of Gene Variation: balanced polymorphism

A
  • maintains a variety of phenotypes within a population. Includes:
    1) Heterozygote advantage,
    2) Minority advantage,
    3) neutral variations
42
Q

Sources of Gene Variation: Polyploidy

A
43
Q

Heterozygote advantage

A
  • (eg. sickle cell anemia). Two parents produce an offspring that is more fit than either parent.
44
Q

Minority Advantage

A
  • : rare phenotypes offer higher fitness. Cycle between high and low frequency. (eg. advantageous against hunters’ search images).
45
Q

Neutral Variations

A
  • may become beneficial if the environment changes.
46
Q

Polyploidy

A
  • : plants have multiple copies of
    alleles introducing more variety and
    preserving different alleles. Can also mask
    effects of a harmful recessive allele.
47
Q

Macroevolution

A
  • is long-term and occurs at a
    level at or higher than species. Species are
    reproductively isolated (via prezygotic and
    postzygotic isolating mechanisms) resulting in a
    lack of gene flow between species.

includes:
1) prezygotic isolation
2) postzygotic isolation

48
Q

prezygotic isolation

A
  • mechanisms are barriers that prevent fertilization and zygote
    formation from occurring between species.
  • includes:
    1) habitat isolation
    2) temporal isolation
    3) behavioral isolation
    4) mechanical isolation
    5) gamete isolation (incompatibility)
49
Q

Habitat Isolation:

A
  • occupying different habitats.
50
Q

Temporal Isolation

A
  • reproducing at different times/seasons.
51
Q

Behavioral Isolation

A
  • different courtship rituals.
52
Q

Mechanical Isolation

A
  • male and female
    genitalia are not compatible.
53
Q

Gamete Isolation (Incompatibility):

A
  • gametes do not recognize or are unable
    to fertilize each other.
54
Q

Postzygotic Isolation

A
  • refers to barriers to organism success after zygote has formed.
  • includes:
    1) hybrid mortality (inviability)
    2) hybrid sterility
    3) hybrid F2 breakdown
55
Q

hybrid mortality (inviability)

A
  • hybrid zygote not-viable and does not survive past embryonic stage (often due to different chromosome numbers).
56
Q

Hybrid Sterility

A
  • hybrid zygote sterile (infertile).
57
Q

Hybrid F2 Breakdown:

A

-Hybrid F2 generation have reduced fitness
compared to their parental generation.

58
Q

Speciation

A
  • is how species form, starting with
    reproductive isolation, which leads to
    interruption of gene flow between populations
    that gradually develop into two species.
  • includes:
    1) allopatric speciation
    2) sympatric speciation
59
Q

Allopatric Speciation:

A
  • occurs due to a geographical barrier.
  • e.g: Adaptive radiation
60
Q

adaptive Radiation:

A
  • occurs when many species arise from one ancestor as they adapt differently to their environments. During adaptive radiation, species can
    specialize to fill different niches within the same environment.
61
Q

Sympatric Speciation:

A

-occurs without a geographical barrier.
- includes:
1) Balanced Polymorphism
2) Polyploidy
3) Hybridization

62
Q

Balanced Polymorphism

A
  • : different phenotypes are isolated within the same area.
63
Q

Polyploidy

A

-: in plants results from nondisjunction during meiosis. (eg. Two
3n organisms - usually sterile - meet and are reproductively compatible).

64
Q

Hybridization

A
  • some hybrids are more fit than purebreds.
65
Q

Theories of Macroevolution include:

A

1) Phyletic gradualism
2) punctuated equilibrium

66
Q

Phyletic gradualism

A
  • : evolution happened gradually via accumulation of small
    intermediary changes. Not likely to be true (not supported by fossil evidence).
67
Q

Punctuated equilibrium

A
  • short spurts of evolutionary changes during periods of stasis
    (supported by fossil evidence).
68
Q

Patterns of Evolution

A

1) Divergent Evolution
2) Convergent Evolution (homoplasy)
3) Parallel Evolution
4) Coevolution

69
Q

Divergent Evolution

A
  • : species diverge from
    common ancestor.
70
Q

Convergent Evolution (Homoplasy):

A
  • unrelated species adapt to similar
    environments becoming more alike
    (analogous structures).
71
Q

Parallel Evolution

A
  • : species diverge from a
    common ancestor but undergo similar
    changes.
72
Q

Coevolution:

A

-two species impart selective
pressure on each other. Classic example is
hummingbirds and flowers.
- includes:
1) camouflage
2) crypsis
3) aposematic coloration
4) mimicry

73
Q

Camouflage (cryptic coloration)

A
  • : match appearance to environment to avoid
    detection. Strictly visual method of
    concealment.
74
Q

Crypsis

A
  • Similar to camouflage, except
    includes olfactory (smell) or auditory
    methods of concealment (ex. scent
    masking, silencing).
75
Q

Aposematic Coloration (warning
coloration):

A
  • vibrant coloration in
    poisonous animals to warn predators.
76
Q

Mimicry:

A
  • evolving to resemble another species.
  • In Batesian mimicry a non-harmful animal resembles a harmful one.
  • In Mullerian mimicry, two poisonous animals resemble each other to
    warn their predator.
77
Q

A Phylogenetic tree

A
  • is a branched diagram that
    shows inferred evolutionary relationships
    between different taxa. A clade is a cluster with
    an ancestor and all its descendants.
  • Phylogenetic trees can either be monophyletic
    (an ancestor and all its descendants) or
    paraphyletic (ancestor and some but not all of
    its descendants).
78
Q

A cladogram

A
  • is a type of phylogenetic tree that
    shows such inferred evolutionary relationships
    among various biological species.
79
Q

An internal node

A
  • is a branch point on a
    cladogram, and represents the splitting
    (divergence) of a single group into two
    descendant groups.
80
Q

Cladogenesis

A
  • refers to the splitting apart of
    evolutionary lineages (formation of new clades).
    Anagenesis describes the gradual evolution of
    an interbreeding population without splitting.
81
Q

Parsimony

A
  • means the simpler the evolutionary
    explanation, the better. Phylogenetic trees
    minimizing evolutionary reversals, convergent
    evolution and parallel evolution are preferred.
82
Q

Polytomy (multifurcation)

A
  • an internal node of a phylogenetic tree that leads to more than two
    tips.

Biology (15 decks)

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