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AP Biology > Unit 7: Natural Selection > Flashcards

Unit 7: Natural Selection Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

natural selection

A
  • due to variation in population and competition for resources
  • organisms with more favorable trait are more likely to survive and reproduce, passing their traits onto the next generation
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2
Q

artificial selection

A
  • organisms with certain traits are bred until population has the trait
  • humans affect variation
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3
Q

types of selection

A

disruptive, stabilizing, directional

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4
Q

disruptive selection

A

selection for two extreme phenotypes and against intermediate phenotype

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5
Q

stabilizing selection

A

selection for intermediate phenotype and against two extreme phenotypes

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6
Q

directional selection

A

selection for AN extreme phenotype and against all other phenotypes

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7
Q

five conditions of h-w equilibrium

A
  1. large population
  2. random mating
  3. no mutations
  4. no genetic flow
  5. no natural selection
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8
Q

genetic drift

A
  • random allele frequency changes
  • reduces population size
  • can decrease genetic diversity, either making harmful alleles fixed (constant) or removing harmful alleles
  • founder’s effect and bottleneck effect
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9
Q

founder’s effect

A

small population is isolated from original population, causing certain alleles to be over/underrepresented

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10
Q

bottleneck effect

A

population is reduced by natural disaster - no selection based on traits (certain alleles can be over/underrepresented)

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11
Q

h-w equilibrium: “p”

A

frequency of dominant allele; 2AA + Aa/2 x # individuals

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12
Q

h-w equilibrium: “q”

A

frequency of recessive allele; 2aa + Aa/2 x # individuals

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13
Q

h-w equilibrium: “p^2”

A

frequency of homozygous dominant; #AA/total

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14
Q

h-w equilibrium: “2pq”

A

frequency of heterozygous; #Aa/total

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15
Q

h-w equilibrium: “q^2”

A

frequency of homozygous recessive; #aa/total

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16
Q

did the population evolve?

A

if allele/phenotype frequency has changed, the population has evolved

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17
Q

biochemical evidence of evolution

A

DNA or protein; comparison of number of differences

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18
Q

morphological evidence of evolution

A

homologous structures, ancestral/derived traits

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19
Q

homologous structures (homology)

A

similar structures due to common ancestry

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20
Q

ancestral/derived traits

A

traits derived from ancestor or from descendants

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21
Q

analogous structures

A

similar structures due to convergent evolution

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22
Q

types of prezygotic isolation

A

behavioral, temporal, geographic, habitat/ecological, mechanical, gametic

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23
Q

types of postzygotic isolation

A

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

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24
Q

hybrid breakdown

A

hybrid becomes less and less viable and fertile with each generation

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25
Q

speciation

A

creation of new species; sympatric and allopatric

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26
Q

sympatric speciation

A
  • new species created from surviving ancestral species, WHILE both continue to inhabit the same region
  • causes: habitat isolation, behavioral isolation, sexual selection, polyploidy
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27
Q

allopatric speciation

A

when biological populations of the same species become isolated due to geographic changes (geographical isolation)

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28
Q

homology

A

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

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29
Q

embryonic homologies (homology)

A

similar early development

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30
Q

vestigial organs (homology)

A

structures with little/no use

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31
Q

molecular homologies (homology)

A

similar DNA and amino acid sequences

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32
Q

convergent evolution

A

distantly related species can resemble one another (similar problems, similar solutions); this similar evolution is NOT because of a recent common ancestor

33
Q

analogous structures

A
  • proof of convergent evolution
  • similar structures that function in similar environments
34
Q

biogeography

A

geographic distribution of species

35
Q

endemic species

A

species found at a certain geographic location and nowhere else

36
Q

last universal common ancestor (LUCA)

A
  • ancestor of bacteria, eukarya, and archaea
  • cellular organism that had a lipid bilayer and used DNA, RNA, and protein
37
Q

monophyletic group

A

common ancestor + all of its descendants

38
Q

paraphyletic group

A

common ancestor + SOME of its descendants

39
Q

polyphyletic group

A

organisms grouped together but are not closely related

40
Q

common ancestry of all life forms (conserved across 3 domains)

A
  • DNA & RNA carry genetic info
  • universal genetic code (codons to amino acids)
  • conserved metabolic pathways
41
Q

conserved elements in eukaryotes

A

cytoskeleton, membrane-bound organelles, linear chromosomes, endomembrane systems

42
Q

horizontal gene transfer

A
  • movement of genes between different domains
  • exchange of transposable elements, plasmids, viral infections, fusion of organisms
43
Q

microevolution

A

change on smallest scale; change in allele frequencies in a population over generations

44
Q

source of genetic variation

A

mutations
- mutations in gametes passed to offspring
- point mutations
- chromosomal mutations –> gene duplication
- fast reproduction: mutations can quickly generate variation
sexual reproduction: shuffle existing alleles (crossing over, etc.)

45
Q

fixed allele

A

all members of a population are homozygous for the same allele; more fixed alleles = less genetic diversity

46
Q

hardy-weinberg equilibrium

A

frequencies of alleles and genotypes in a population’s gene pool remain CONSTANT over generations unless acted upon by agents other than sexual recombination

47
Q

three major mechanisms of evolution

A

natural selection, genetic drift, gene flow

48
Q

natural selection IN microevolution…

A

causes differential reproductive success

49
Q

genetic drift IN microevolution

A

unpredictable fluctuation of alleles from one generation to the next

50
Q

gene flow IN microevolution

A

population loses/gains alleles due to immigration or emigration

51
Q

balancing selection

A
  • diploidy: inherit 2 alleles; recessive allele is hidden in heterozygotes
  • heterozygote advantage: heterozygotes have better survival
52
Q

sexual selection

A

certain individuals more likely to obtain mates; intrasexual and intersexual selection

53
Q

intrasexual selection

A

competition within same sex

54
Q

intersexual selection

A

mate choice

55
Q

natural selection canNOT fashion perfect organisms

A
  1. selection can only edit existing organisms
  2. evolution is limited by historical constraints
  3. adaptations are often compromises
  4. chance, natural selection, and the environment interact
56
Q

macroevolution

A

evolutionary change above species level (cumulative effects of speciation over long periods of time)

57
Q

reproductive isolation

A

processes that prevent interbreeding across species; prezygotic isolation and postzygotic isolation

58
Q

hybrid zones

A

incomplete reproductive barriers; effects: reinforcement, fusion, stability

59
Q

fusion

A

breakdown of reproductive barriers (if hybrid is as fit as parents)

60
Q

reinforcement

A

strengthening of reproductive barriers (if hybrid is less fit than parents)

61
Q

stability

A

no change in reproductive barriers

62
Q

gradualism (speciation)

A

common ancestor; slow, constant change

63
Q

punctuated equilibrium (speciation)

A

long periods of stasis punctuated by sudden change seen in fossil record

64
Q

how did life arise?

A
  1. small organic molecules were synthesized
  2. small molecules –> macromolecules
  3. molecules packaged into protocells (membrane-containing droplets)
  4. self-replicating molecules allow for inheritance
65
Q

“RNA world”

A

first genetic material was likely RNA; first catalysts were ribozymes (RNA)

66
Q

synthesis of compounds on early earth

A
  • early atmosphere: H2O vapor, N2, CO2, H2, H2S, methane, ammonia
  • energy: lightning & UV radiation
  • conditions favored synthesis of organic compounds: a primitive soup
67
Q

endosymbiont theory

A
  • mitochondria and plastids (chloroplasts) formed from small prokaryotes living in larger cells
  • evidence: replication by binary fission; singular, circular DNA; ribosomes to make proteins; enzymes similar to living prokaryotes; two membranes
68
Q

effect of continental drift/pangaea

A

movement of continental plates change geography and climate on earth, which leads to speciation and extinction

69
Q

mass extinctions =

A

diversity of life

70
Q

major periods in earth’s history END with

A

mass extinctions

71
Q

major periods in earth’s history START with

A

adaptive radiations

72
Q

major events during precambrian era

A

photosynthesis, atmospheric O2; eukaryotes

73
Q

major events during paleozoic era

A

plants invade land, many animals appear; Permian extinction (-96% species)

74
Q

major events of mesozoic era

A

formation of Pangaea; Cretacious Extinction (asteroid)

75
Q

major events of cenozoic era

A

primates!

76
Q

adaptive radiations

A
  • many species arise from single common ancestor
  • occurs when organisms make way to new, distant areas (allopatric speciation) or when environmental change causes extinctions which opens up new niches for survivors
77
Q

evo-devo

A

evolutionary + developmental biology; evolution of new forms results from changes in DNA or regulation of developmental genes

78
Q

heterochrony

A

evolutionary change in rate of developmental events

79
Q

homeotic genes

A

master regulatory genes determine location and organization of body parts

AP Biology (9 decks)

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