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AP Biology > Ch. 10: Evolution > Flashcards

Ch. 10: Evolution Flashcards

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1
Q

Evolution

A

the process by which frequency of heritable traits in a pop. changes from one generation to the next

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2
Q

Theory or Jean-Baptiste Lamarck

A
  1. Use and disuse: body parts of organisms develop w/ increased usage while unused parts weaken
  2. Inheritance of acquired characteristics: body features acquired in lifetime can be passed to offspring… false. only changes in DNA can be passed to offspring
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3
Q

Darwin’s theory of evolution

A

The Origin of Species

natural selection and “survival of the fittest”

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4
Q

Paleontology (evolution)

A

provides fossils that reveal the prehistoric existence of extinct species so changes can be studied

  • often found among sediment layers, where deep = old
  • age of fossil can be determined by C-14 dating
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5
Q

Biogeography (evolution)

A

geography used to describe distribution of species
unrelated species in different regions of the world look alike when in similar environments so provides evidence for natural selection
Ex. sugar glider of Australia and flying squirrel of North America

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6
Q

Embryology (evolution)

A

similar stages in development (ontogeny) among related species –> help est. evolutionary relationships (phylogeny)
Ex. gills and tails found in fish, chicken, pig, and human embryos

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7
Q

Homologous structures

A

body parts that resemble one another in different species bc they have evolved from a common ancestor
may look different but be similar in pattern
Ex. forelimbs of cats, bats, whales, and humans all have similar bone structure

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8
Q

Vestigial structures

A

homologous structures that have lost their function

Ex. limbs in snakes, wings of flightless birds

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9
Q

Analogous structures

A

body parts that resemble one another in different species that evolved independently as adaptations to their environment
Ex. fins in fish or wings in birds

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10
Q

Molecular biology (evolution)

A

examines nucleotide and DNA similarities between related species… more related DNA = more related species
also, all living things share the same genetic code

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11
Q

Natural selection

A

differences in survival and reproduction among individuals in a pop. as a result of their interaction with the environment
some alleles suit organisms more favorably towards their environment

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12
Q

Adaptations –> fitness

A

superior traits increase organisms likelihood of survival and pass on these good traits to offspring, while those w bad traits die

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13
Q

Darwin’s theory of natural selection (8)

A
  1. Populations possess an enormous reproductive potential
  2. Population sizes remain stable
  3. Resources are limited: as pop. grows larger, food/ water/ light does not increase
  4. Individuals compete for survival: bc of #3
  5. There is variation among individuals in a population
  6. Much variation is heritable: acquired traits are not passed on
  7. Only them most fit individuals survive
  8. Evolution occurs as favorable traits accumulate in the pop.: changes in proportion of gene pool
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14
Q

Stabilizing selection graph

A

peak in middle, bell curve like shape

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15
Q

Directional selection graph

A

peak on one side, either left or right

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16
Q

Disruptive selection graph

A

2 peaks on each side left and right, dip in middle

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17
Q

Sexual selection graph

A

similar to disruptive w/ 2 peaks on each side but one bears more area (male/ female)

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18
Q

Stabilizing selection

A

eliminates those w/ extreme/ unusual traits so those w/ most common trait are best adapted and thus best represented in pop.
maintains existing population frequencies of common traits and selects against other trait variations

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19
Q

Directional selection

A

favors traits at one extreme of a range of traits, and the other extreme is selected against
over many generations favored traits become more and more extreme and allele frequencies in pop. change
Ex. finch’s beaks, insecticide resistance, peppered moth, season creep

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20
Q

Peppered moth (industrial melanism)

A

ex. of directional selection
light moth was good before industrial revolution bc blended in, and dark moth not really seen bc easily spotted to be eaten. then soot made dark moth more easily camouflaged so that was the trait selected for

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21
Q

Disruptive selection

A

environment favors extreme or unusual traits while selecting against common ones
Ex. weeds are either really tall in wild of really short to avoid mowing

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22
Q

Sexual selection, Male competition, Female choice, Sexual dimorphism

A

differential mating of males and females in a pop.
females look for quality males look for quantity
Male competition: contests of strength with strongest male getting to mate; antlers, horns, muscles
Female choice: traits or behaviors in males that are attractive to females; colorful plumage or elaborate mating
sexual selection often leads to sexual dimorphism which is form of disruptive selection

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23
Q

Artificial selection

A

form of directional selection carried out by humans to get desired traits
Ex. dog breeding, modification of crops

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24
Q

Sources of variation in evolution

A

mutations, sexual reproduction and genetic recombination, diploidy, outbreeding, balanced polymorphism and the heterozygote advantage/ hybrid vigor/ frequency-dependent selection

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25
Q

Mutations (variation)

A

provide raw material for new variation, invent alleles that never existed in gene pool and can then be rearranged even more
Ex. antibiotic and pesticide resistance introduced in pop. by random mutation, although these alleles may have already existed in pop. the introduction of antibiotics “selected” for those individuals

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26
Q

Sexual reproduction (variation)

A

creates individuals w/ new combinations of alleles (genetic recombination)

  1. Crossing over (prophase I of meiosis)
  2. Independent assortment of homologues
  3. Random joining of gametes
27
Q

Diploidy (variation)

A

presence of two copies of each chromosome in a cell so there are two alleles at a single gene locus, so allowed for recessive to be hidden under dominant which is more variation bc more alleles

28
Q

Outbreeding (variation)

A

mating with unrelated partners increases possibility of mixing diff. alleles and create new allele combinations

29
Q 
Balanced polymorphism (variation)
Heterozygote advantage
Hybrid vigor (heterosis)
Frequency-dependent selection (minority advantage)
A

maintenance of different phenotypes in pop.
many times, one phenotype is more advantageous, so the other alleles decreased are selected against, but polymorphism (2+ phenotypes) is maintained by:
- Heterozygote advantage: Ex. sickle cell disease homozygous is healthy/ fatal but heterozygous just weakens the blood oxygen carrying ability, but provides resistance to malaria so lots of ppl in Africa have it. keeps all three combos feasible
- Hybrid vigor: superior quality of offspring from crosses between two diff. inbred strains of plants
- Frequency-dependent selection (minority advantage): least common phenotypes are selected for. but as they’re selected for they become common so are selected against. pop. fluctuates between low and high frequencies of trait

30
Q

Human impact on variation (thus evolutionary potential)

A

reduce size and thus genetic variation of pop through

  • Monocultures: only one of many vile varieties of plants are used, wild varieties die, these types of plants have no genetic variation so v susceptible to disease/ environmental change
  • Overuse of antibiotics: we have made bacteria resistant
31
Q

Natural selection (allele frequency)

A

increase or decrease in allele frequency due to impact of environment

32
Q

Mutations (allele frequency)

A

introduce new alleles that may provide selective advantage, though most are deleterious (harmful)

33
Q

Gene flow (allele frequency)

A

movement of individuals between populations resulting in the removal of alleles from the pop. when they leave (emigration) and introduction of alleles when they enter (immigration)

34
Q

Genetic drift (allele frequency)

A

random increase or decrease of alleles, happens by chance
when pop. is small, effect of genetic drift can be v strong and dramatically influence evolution
think stats

35
Q

Founder effect (genetic drift)

A

allele frequencies in a group of migrating individuals are, by chance, not the same as their pop. of origin
loss of genetic variation when smaller pop. is est. from larger one
Ex. polydactyly is common in Amish

36
Q

Bottleneck effect (genetic drift)

A

population undergoes dramatic decrease in size
regardless of cause (catastrophe, predation, disease) the small resulting pop. is v vulnerable to genetic drift
when bottlenecks caused by forces that strike individuals randomly, gene frequencies may change by chance like geological events

37
Q

Nonrandom mating (allele frequency)

A

individuals choose mates based on specific traits and only alleles possessed by mating individuals passed down
Ex. inbreeding, sexual selection

38
Q

Hardy-Weinberg equilibrium (conditions)

A

allele frequencies in a pop. remain constant from generation to generation, and there is no evolution
1. All traits are selectively neutral (no natural selection)
2. Mutations do not occur
3. The population must be isolated from other populations (no gene flow)
4. The population is large (no genetic drift)
5. Mating is random
will never happen, but used to show how allele frequencies are changing, which conditions are being violated and what mechanisms are driving evolution of pop.

39
Q

Genetic equilibrium formulas and variables

A
  • p, q: frequency of each allele
  • p^2: frequency of homozygous dominant genotype
  • q^2: frequency of homozygous recessive genotype
  • 2pq: frequency of heterozygous genotype
  • p + q = 1 (all alleles sum to 100%)
  • p^2 + 2pq + q^2 = 1 (all individuals sum to 100%)
40
Q

Allopatric speciation

A

pop. is divided by a geographic barrier (mountains, rivers), preventing mating between the two groups
once reproductively isolated, gene frequencies in the two pop.s can diverge due to natural selection (environments might be different), mutation, or genetic drift; over time become so different that can no longer mate w/ each other and speciation has occured
[geographic barrier –> reproductive isolation –> differential evolution –> reproductive barriers –> new species]

41
Q

Sympatric speciation

A

formation of new species w/ out geographic barrier

Ex. balanced polymorphism, polyploidy, hybridization

42
Q

Balanced polymorphism (sympatric speciation)

A

may lead to speciation
Ex. population of insects has polymorphism for color, and each color provides camouflage to diff. things. if not camouflaged, is eaten so only insects w/ same color can associate and mate –> same colored insects reproductively isolated from other subpopulations and their gene pools diverge

43
Q

Polyploidy (sympatric speciation)

A

possession of more than normal 2n set of chromosomes
often found in plants where 3n and 4n are ok and common
diploid + diploid = tetraploid zygote; this tetraploid will continue to produce diploid games so reproductive isolation (speciation) occurs within one generation

44
Q

Hybridization (sympatric speciation)

A

two different forms of species (or closely related species normally reproductively isolated) mate and produce progeny along geographic boundary called hybrid zone
these individuals adapt to hybrid zone and eventually diverge

45
Q

Adaptive radiation

A

relatively rapid evolution of many species from a single ancestor
occurs when ancestral species introduced to area where diverse geographic/ ecological conditions available available and variants adapt to each and diverge
Ex. marsupials of Australia, 14 Galapagos finches, occurred after each of the 5 big mass extinctions

46
Q

Pre-zygotic isolating mechanisms

Habitat isolation, Temporal isolation, Behavioral isolation, Mechanical isolation, Gametic isolation

A

mechanisms that prevent fertilization to maintain reproductive isolation w/out geographic barrier between species

  1. Habitat isolation: species don’t encounter each other
  2. Temporal isolation: different mating seasons
  3. Behavioral isolation: don’t recognize another species for mating bc of improper mating rituals/ signals
  4. Mechanical isolation: can’t do the do
  5. Gametic isolation: the gametes of one sex do not survive in the environment of gametes of the other sex
47
Q

Post-zygotic isolating mechanisms

Hybrid inviability, Hybrid sterility, Hybrid breakdown

A

mechanisms that prevent the formation of fertile progeny to maintain reproductive isolation w/out geographic barrie between species

  1. Hybrid inviability: zygote fails to develop properly and dies before being able to reproduce
  2. Hybrid sterility: donkey + horse = mule can’t have babies
    8: Hybrid breakdown: hybrids produce offspring w/ reduces viability/ fertility
48
Q

Patterns of evolution (4)

A
  1. Divergent evolution
  2. Convergent evolution
  3. Parallel evolution
  4. Coevolution
49
Q

Divergent evolution

A

2+ species that originate from a common ancestor and become increasingly different over time
may happen as result of allopatric or sympatric speciation or by adaptive radiation

50
Q

Convergent evolution

A

describes two unrelated species that share similar (analogous) traits that resulted not bc of common ancestor, but bc each species had independently adapted to similar ecological conditions/ lifestyles
Ex. sharks, penguins and dolphins have fins

51
Q

Parallel evolution

A

two related species/ two related lineages that have made similar evolutionary changes after their diverges from a common ancestor
Ex. marsupial and placental mammals have independently evolved similar adaptations when ancestors encountered compatible environments

52
Q

Coevolution

A

one species evolves in response to new adaptations in another species
Ex. prey starts to run faster so predator also runs faster (allele wise bc selection)
occurs between predator and prey, plants and plant-eating insects, pathogens and animal immune systems

53
Q

Microevolution

A

details of how populations of organisms change from generation to generation and how new species originate

54
Q

Macroevolution, Phylogeny

A

general pattens of change in groups of related species that have occurred over broad periods of geologic time
patterns determine phylogeny: evolutionary relationships among species/ groups of species
fossil evidence has led to two contrasting theories: phyletic gradualism, punctuated equilibrium

55
Q

Phyletic gradualism (macroevolution)

A

argues that evolution occurs by the gradual accumulation of small changes
individual speciation events/ major changes in lineages occur over long periods of geologic time w/ fossil evidence providing only snapshots of evolutionary process and showing only major changes, intermediate stages not represented testifying incompleteness of fossil record

56
Q

Punctuated equilibrium (macroevolution)

A

argues that evolutionary history consists of geologically long periods of stasis w/ no evolution, interrupted by geologically short periods of rapid evolution ranging over tens of thousands of years
fossil record consists of fossils mostly from stasis period w/ few from short evolutionary bursts; absence of intermediate fossils is confirmation of this rapid evolution

57
Q

Chemical evolution

A

study of how life began and formation of first living things

58
Q

How old is the Earth?

A

4.6 billion years, inhospitable for life for billions of years

59
Q

Primordial atmosphere

A

primarily of CO2 and N2, but little or no O2

60
Q

Stanley Miller experiment

A

simulated primordial conditions by applying electric sparks to simple gases (no oxygen) connected to a flask of heated water, after a week the water contained various organic molecules including amino acids

61
Q

Protobiont

A

precursors of cells, able to carry out chemical reactions within a membrane like border

62
Q

Endosymbiotic theory

A

describes how eukaryotic cells originated from a mutually beneficial association among various kinds of prokaryotes
specifically, mitochondria, chloroplasts, and other organelles est. residence inside another prokaryote to make eukaryote

63
Q

Endosymbiotic theory evidence

A

Mitochondria and chloroplasts have their own DNA and ribosomes which is similar to that of bacteria
Mitochondria and chloroplasts reproduce independently of their eukaryotic host cell by process similar to binary fission of bacteria, and have two membranes

64
Q

Origin of life steps (9)

A
  1. Earth and its atmosphere formed 4.6 bya
  2. Primordial seas formed as Earth cooled
  3. Organic molecules synthesized: “soup” w/ UV energy, amino acids formed
  4. Polymers and self-replicating molecules were synthesized: RNA world hypothesis
  5. Organic molecules were concentrated and isolated into protobionts: liposomes
  6. Primitive heterotrophic prokaryotes formed ~3.9 bya
  7. Primitive autotrophic prokaryotes were formed
  8. Oxygen and ozone layer formed and abiotic chemical evolution ended
  9. Eukaryotes formed (endosymbiotic theory)

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