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AP Bio > Unit 7: Natural Selection > Flashcards

Unit 7: Natural Selection Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Several examples of evidence for evolution from different scientific disciplines and how each supports change in populations over time

A
  1. Sticklebacks & having a pelvic spine
  2. Finches long beak vs small beak - had unique beak shapes adapted to the food sources available in their specific habitat
  3. Rock pocket mice - on dark volcanic rock = darker mice, lighter sand colored mice
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2
Q

Homologous structures

A

structures similar anatomy from common ancestors (eg. forelimbs of human/cat/whale/bat) but differ in function

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3
Q

Analogous structures

A

various structures in different species have same function but have evolved separately, do not share common ancestor (bug wings vs bird wings) + do not necessarily have same structures

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4
Q

How do Homologous and Analogous structures relate to evolution?

A

Noting the structures of these organisms help understand whether they share a common ancestor

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5
Q

Main ideas of Natural Selection

A

Evolution is change in species over time.
There is overproduction of offspring, which leads to competition for resources.
Heritable variations exist within a population.
These variations can result in differential reproductive success.
Over generations, this can result in changes in the genetic composition of the population.

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6
Q

Main ideas of Natural Selection
2

A

Competition for limited resources results in differential survival
Evolutionary Fitness: Individuals w/ more favorable adaptations are more likely to survive & produce more offspring, & pass on traits
If environ changes or individuals move to new environ, new adaptations & new species may arise.
Populations evolve, not individuals.

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7
Q

Evidence for Evolution:
1. Direct Observations

A

Examples: Insect populations become resistant to pesticides (DDT)
Antibiotic-resistant bacteria (MRSA)
Peppered moth (pollution in city vs. country)

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8
Q

Evidence for Evolution:
2. Homology

A

Characteristics in related species can have underlying similarity even though functions may differ

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9
Q

Embryonic homologies

A

Similar early development (eg. vertebrate embryos with tail & pharyngeal pouches) (DISCREDITED)

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10
Q

Vestigial organs

A

Structures w/little or no use (eg. flightless bird wings)

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11
Q

Molecular homologies

A

Similar DNA and amino acid
sequences

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12
Q

Evidence for Evolution:
3. Fossil Record

A

Fossils found in sedimentary rock
Show evolutionary changes that occur over time & origin of major new groups
Transitional forms = links to modern species

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13
Q

Evidence for Evolution:
4. Biogeography

A

Geographic distribution of a species
Species in nearby geographic areas resemble each other
Continental drift & Pangaea explains similarities on different continents
Endemic species: found at a certain geographic location & nowhere else
Ex: Marine iguanas in the Galapagos

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14
Q

Adaptations

A

Enhance an organism’s ability to survive & reproduce in specific environments (fitted to environ)
Ex: Desert fox - large ears, arctic fox - small ears

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15
Q

Variations

A

Any diff between cells, individual organisms, or organsims groups of any species caused by genetic diff or by effect of environmental factors on the expression of the genetic potentials

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16
Q

Time effect on Evolution

A

Can’t evolve in one generation

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17
Q

Reproductive success

A

Passing of fittest genes onto next generation so they can pass those genes on (tally of offspring produced by an individual)

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18
Q

Heritability

A

Amount of phenotypic (observable) variation in a population that is attributable to individual genetic differences

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19
Q

What are the only source of new genes and new alleles?

A

Mutations:

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20
Q

The three ways in which sexual reproduction
produces genetic variation.

The conditions for Hardy-Weinberg equilibrium.

How to use the Hardy-Weinberg equation to
calculate allele frequencies to test whether a
population is evolving.

What effects genetic drift, migration, or selection
may have on a population, and analyze data to
justify your predictions.

A
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21
Q

Microevolution

A

Evolution on smallest scale
Change in allele frequencies in a population over generations

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22
Q

Sources of Genetic variation

A

Mutations
Fast Reproduction
Sexual Reproduction

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23
Q

Mutations

A

Only source of new alleles & new genes
Mutations in gametes passed to offspring
Point mutations
Chromosomal mutations → gene duplication

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24
Q

Sexual Reproduction

A

shuffle existing alleles
1. Crossing over
2. Independent assortment
3. Random Fertilization

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25
Q

Conditions for Hardy-Weinberg Equilibrium

A

No mutations (no new alleles in gene pool)
Random mating. (no sexual selection)
No natural selection.
Extremely large population size. (no genetic drift- change in frequency of an existing gene variant in the population due to random chance)
No gene flow. (no emigration, immigration - movement in or out of the population or reproductive contact with other populations)

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26
Q

If any of the conditions for the Hardy-Weinberg Equilibrium are NOT met…?

A

Microevolution is occurring

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27
Q

Hardy-Weinberg Equation

A

p = dominant allele
q = recessive allele
p+q=1
homozyg. dominant = p^2
homozygous recessive = q^2
hetero. = 2pq

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28
Q

Genetic Drift

A

Changes in gene/allele frequencies from generation to generation as a result of random processes
Effect: changes gene frequencies (increases or decreases genetic diversity)
Significant genetic drift in small populations

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29
Q

2 types of genetic drift

A

Founder Effect
Bottleneck Effect

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30
Q

Bottleneck Effect

A

Severe drop in population size
Certain alleles may be over/under represented

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31
Q

Founder Effect

A

few individuals become
isolated from larger population → certain alleles over/under represented

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32
Q

Gene Flow

A

population gains/loses alleles
due to immigration or emigration

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33
Q

Migration effect on pop

A

changes # of species in a population + what genes are present

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34
Q

Natural Selection effect on pop

A

genes in a pop will adjust to become more favorable/fitt for the current environment (sexual/natural)

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35
Q

Natural selection can occur in 3 ways:

A

Directional Selection
Disruptive Selection
Stabilizing Selection

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36
Q

Directional selection

A

beak size of birds increase/decrease during wet/dry seasons

37
Q

Disruptive selection

A

want to be either rock pocket mice or sand pocket mice

38
Q

Stabilizing selection

A

Want to be very mid: average human birth weight

39
Q

Intrasexual selection:

A

competition within same sex

40
Q

Intersexual selection:

A

mate choice

41
Q

Taxonomic categories

A

Kingdom, Phylum, Class, Order, Family, Genus, Species. Domain (Archaea, bacteria, Eukarya) is the biggest. The further into the tree you go, the closer the organisms are to each other.

Ordered division of organisms
based on similar/different
characteristics
Dear King Philip Came Over
For Good Soda
Each category at any level is
called a taxon.

42
Q

Systematics used to develop phylogenetic trees

A

Using fossils, morphology (homologous structures), & molecular evidence (DNA/amino acids), one creates a tree, placing the most closely related organisms together.

43
Q

Phylogenetic Tree

A

Branching diagram that shows evolutionary history of a group of organisms
Each branch = closer hallway to other species, can represent genetic change or time (common ancestor),

44
Q

3 Domains of Life (similarities & differences)

A

Eukarya: Eukaryotes, have a nucleus, membrane bound organelles, introns, histone proteins associated with DNA, but have a linear chromosome.

Archaea: don’t have a nuclear membrane, don’t have membrane bound organelles, do have introns, do have histone proteins associated w/ DNA, and do have a circular chromosome

Bacteria: share same traits as Archaea but don’t have introns or histone proteins associated w/ DNA

45
Q

Elements conserved across all 3 domains

A

DNA and RNA are carriers of genetic info
Universal genetic code (codons → amino acids)
Conserved metabolic pathways

46
Q

Conserved elements in Eukaryotes

A

Cytoskeleton
Membrane-bound organelles
Linear chromosomes
Endomembrane systems (including nuclear envelope)

47
Q

what is the significance of widely conserved processes across the three domains of life?

A

If a gene is widely conserved = crucial to species’s survival.
Gene = similar across organisms of all domains

48
Q

Divergent Evolution

A

when individuals in one species, or closely related species, acquire enough variations in their traits that it leads to two distinct new specie (one common ancestor)

49
Q

Convergent Evolution

A

two unrelated species develop similar traits because they live in similar environments. (no common ancestor)

50
Q

Cladogram

A

Clade = group of species that includes an ancestral
species + all descendents
Shared derived characteristics (evolutionary novelties) are used to construct cladograms ex: hair

51
Q

Horizontal Gene Transfer

A

Movement of genes between different domains
Exchange of transposable elements, plasmids, viral infections, fusion of organisms

52
Q

Speciation may occur when two populations become
reproductively isolated from each other.

There are prezygotic and postzygotic barriers that maintain
reproductive isolation in natural populations.

How allopatric and sympatric speciation are similar and different.

How a change in chromosome number can lead to sympatric
speciation.

Why speciation rates are often rapid in situations where adaptive
radiation occurs or during times of ecological stress.

The connection between speciation in a isolated population and a
change in gene frequency, a change in the environment, natural
selection, and/or genetic drift.

How punctuated equilibrium and gradualism describe two
different tempos of speciation.

A
53
Q

Species

A

pop or group of pops: members have the potential to interbreed in nature & produce viable,fertile offspring (can make more babies) Reproductively compatible

54
Q

Reproductive isolation

A

barriers that prevent members of 2
species from producing viable, fertile hybrids

55
Q

Prezygotic Barriers

A

Prevent mating or hinder fertilization
Types: Habitat isolation, Temporal isolation, Behavioral isolation, Mechanical isolation, Gametic isolation

56
Q

Postzygotic Barriers

A

Prevent hybrid zygote from developing into fertile adult
Types: Reduced hybrid viability, Reduced hybrid fertility, Hybrid breakdown

57
Q

can speciation occur when two populations become reproductively isolated from each other?

A

yes

58
Q

Allopatric Speciation

A

Geographically isolated
pops (physical barrier), Caused by geologic events or processes -> evolve diff species
Evolves by natural selection & genetic drift
shares common ancestor
Ex: Squirrels on N/S rims of
Grand Canyon

59
Q

Sympatric Speciation

A

Overlapping populations w/ in same geographic area -> just randomly evolves into separate species w/o geographical separation
shares common ancestor
Gene flow between subpops blocked by: polyploidy, habitat differentiation, sexual selection
Ex: polyploidy in 80% of plants
(oats, cotton, potatoes, wheat)

60
Q

Autopolyploid (Sympatric speciation thru diff chromosome numbes)

A

extra sets of chromosomes
Failure of cell division (2n → 4n)
Ex: Strawberries are 4n, 6n, 8n,
10n (decaploid)!

61
Q

Allopolyploid (Sympatric speciation thru diff chromosome numbes)

A

2 species produce a hybrid
Species A (2n=6) + Species B (2n=4) → Hybrid (2n=10)

62
Q

How does polyploidy cause sympatric speciation?

A

genetic condition immediately causes reproductive isolation
when an organism has more than two sets of chromosomes
& cannot breed w/ parent pop

63
Q

How punctuated equilibrium and gradualism describe two
different tempos of speciation.

A

Gradualism common ancestor and slow constant change
Punctuated- long periods of stasis punctuated by short bursts of significant change

64
Q

Adaptive radiation

A

when many new species arise from a single common ancestor, , they fill different ecological niches/roles in their communities (that are extinct/dying) so they do not fight one another and the speciation rates raise, especially in places where a disaster occurs like in volcanoes

65
Q

species in an isolated pop; change in gene frequency, a change in the environment, natural selection, and/or genetic drift.

A

will lose genes or alleles over time, which results in a decrease in fitness & local adaptation, and an increase in expression of deleterious or lethal alleles, they will diverge from one another, both in the way they look & genetically

66
Q

Gradualism speciation

A

Common ancestor
Slow, constant change in morphology as they adapt

67
Q

Punctuated Equilibium speciation

A

Eldridge & Gould
Long periods of stasis (no change)
punctuated by sudden change seen in fossil record

68
Q

Hybrid Zones

A

Incomplete reproductive barriers
Possible outcomes: reinforcement, fusion(breakdown of reproductive barriers), stability

69
Q

Morphology

A

by body shape, size, and
other structural features

70
Q

Ecological

A

niche/role in community

71
Q

How did life arise?

A

1) Small organic molecules were synthesized (amino
acids, nitrogenous bases)
2) Small molecules → macromolecules (proteins,
nucleic acids)
3) Molecules packaged into protocells (membrane-containing droplets)
4) Self-replicating molecules allow for inheritance
“RNA World”: 1st genetic material most likely RNA
First catalysts = ribozymes (RNA)

72
Q

The age of the Earth and when prokaryotic & eukaryotic life emerged

A

Earth is 4.6 billion years old.
First life forms appeared 3.8 billion years ago

73
Q

Characteristics of the early planet and its atmosphere

A

Early atmosphere = H2O
vapor, N2, CO2, H2, H2S
methane, ammonia
Energy = lightning & UV
radiation
Conditions favored synthesis
of organic compounds - a
“primitive soup”

74
Q

Miller & Urey

A

Tested Oparin-Haldane
hypothesis
Simulated conditions in lab Produced amino acids

75
Q

Methods used to date fossils and rocks and how fossil evidence
contributes to our understanding of changes in life on Earth

A
  1. Relative Dating:
  2. Radiometric Dating
    -> can show an organisms adaptations to the Earth
76
Q

Relative Dating

A

Uses order of rock strata to determine relative age of fossils

77
Q

Radiometric Dating

A

Measures the decay of radioactive isotopes present in layers where fossils are found. (Half-life): # of years for 50% of original sample
to decay

78
Q

Endosymbiont Theory Evidence

A

Mitochondria & plastids (chloroplasts) formed from small prokaryotes living in larger cells
1. Replication by binary fission
2. Single, circular DNA (no histones)
3. Ribosomes to make proteins
4. Enzymes similar to living prokaryotes
5. Two membranes

79
Q

How continental drift can explain the current distribution of
species.

A

movement of continental plates changes geography & climate -> changes environ a species lives in which cause extinctions & speciation. + explain many similar species on different mainlands. (pangaea = supercontinent)

80
Q

How extinction events open habitats that may result in adaptive radiation.

A

Extinction events open habitats bx when mass # species dies, another must fill its roll in the environment or its niche. The need to fill the ecological niche is what leads to adaptive radiation which is a period of rapid evolutionary change to fill an ecological niche.

81
Q

Adaptive Radiation

A

Many new species arise from a single common ancestor
Occurs when: A few organisms make way to new, distant areas
(allopatric speciation)
Environmental change -> extinctions-> open up new niches for survivors

82
Q

Evolution of new forms results from

A

from changes in DNA/ regulation of developmental genes

83
Q

How behaviors are the result of natural selection

A

includes the ways that animals interact with other organisms & the physical environment and behavior is shaped by natural selection, behaviors increase an organism’s fitness + survival / reproduction

84
Q

How innate behaviors increase survival and reproductive
fitness

A

provides the animal with the knowledge of when to do something that they need to do for survival (flower knowing when to bloom, birds knowing when to migrate), Ensures that activities essential to survival are performed correctly w/o practice

85
Q

how does learned behavior increase fitness

A

the animal can learn a skill essential for survival/ climate change ex: habituation (loss of stimuli sense), imprinting

86
Q

How organisms use communication to increase fitness

A

they use different types of communication ( pheremones, visual signals, tactile (touch), auditory signals) to reproduce, locate a food source, become aware of predators etc.

87
Q

Role of altruism in kin selection

A

selfless behavior
Reduce individual fitness but increase fitness of others in pop (i.e. bee societies; naked mole rats) genes more likely passed down

88
Q

Role of Inclusive fitness in kin selection

A

Total effect of producing own offspring (pass on
genes) + helping close relatives

kin selection: type of natural selection; altruistic behavior enhances reproductive success of relatives

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