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BIOL 360 - General Ecology > Evolution > Flashcards

Evolution Flashcards

1
Q

What is the relationship of ecology with evolution?

A

Because evolution can occur very rapidly, ecologists must be aware of evolution at all times.

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2
Q

Bolgard

A

A transgenic cotton variety that produces Bt toxin, a biological insecticide that is poisonous to larvae of butterflies and moths.

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3
Q

What is evolution?

A

(1) change in the composition of a population from one generation to the next.
(2) change in allele frequencies across generations or between populations

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4
Q

When does evolution happen?

A

Evolution happens when individuals with certain traits survive and reproduce at higher rates than others.

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5
Q

What would a graph of offspring vs parents look like if offspring tend to resemble their parents?

A

Linear

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6
Q

What would a graph of offspring vs parents look like if offspring tend NOT to resemble their parents?

A

Scattered plot

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7
Q

What is the theory of natural selection?

A

The theory of evolution by natural selection is that when there is variation (1) in a population that is heritable (2) and that influences survival and reproductive success (3), the composition of the population automatically changes from one generation to the next (evolution happens!).

Traits associated with survival and reproduction become common; traits associated with untimely death and reproductive failure become rare.

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8
Q

What are the assertions of the theory of natural selection?

A

(1) Individuals vary
(2) Heritable traits (children resemble parents)
(3) Selective survival/reproduction (non-random)

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9
Q

What happens when one or more of the assertions of natural selection does not apply?

A

The composition of the population may fluctuate across generations, but substantial change will accrue only slowly, if at all

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10
Q

What is the relationship between natural selection and population genetics?

A

The theory of evolution by natural selection can be rephrased in the language of modern population genetics.

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11
Q

How can you rephrase the theory of natural selection in terms of modern genetics?

A

(1) Individuals vary in phenotype. That is, they look, function, and act differently.
(2) Differences in phenotype are at least partly due to differences in genotype. That is, some of the variation among individuals in appearance, function, and behavior arises because they carry different alleles for some of their genes.
(3) Some phenotypes, and thus some genotypes, survive and reproduce at higher rates than others.

As a result, the relative abundances of genotypes change from one generation to the next (evolution!).

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12
Q

Phenotype

A

An individual’s phenotype is any observable or measurable aspect of its appearance, structure, behavior, or physiological function.

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13
Q

Genotype

A

An individual’s genotype is the combination of alleles the individual carries. Less formally, its genotype is its genetic make-up.

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14
Q

Alleles

A

Alleles are different versions of a gene. The term may be used to distinguish versions of a gene that differ in nucleotide sequence, amino acid sequence, or both.

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15
Q

Fitness

A

An individual’s lifetime comparative reproductive success. In practice, this is often measured as the number of offspring that are produced that themselves grow up to produce offspring.

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16
Q

Codominant

A

Codominant describes the relationship between two alleles when heterozygotes (Aa individuals, for example) have a different phenotype than either of the homozygotes (AA and aa individuals).

Typically used when the phenotype of the heterozygotes is intermediate between the phenotypes of the homozygotes.

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17
Q

When will phenotype not necessarily reveal genotype?

A

When the alleles are not codominant. (e.g. Aa looks like AA)

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18
Q

Frequency

A

Relative abundance (#with a trait/ #total individuals)

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19
Q

Calculate the frequency of the ll genotype if there are 4 ll individuals in a population of 10.

A

0.4

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20
Q

How can you calculate genotype counts?

A

individuals with genotype/#total individuals

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21
Q

How can you calculate frequencies of alleles A and B in a population?

A

Frequency of allele A = (2(AA) + AB)/(population*2)

Frequency of allele B = (2(BB) +AB)/(population*2)

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22
Q

Blending theory

A

Antiquated theory of inheritance where offspring would have some intermediate level of a trait found in both parents (e.g tall + short parents = medium height offspring)

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23
Q

Factors

A

Mendel’s initial term for what we now know as genes. He realized that inherited traits were discrete and passed on discrete factors.

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24
Q

What are the ways that selection could happen?

A

(1) Stabilizing selection
(2) Directional selection
(3) Disruptive selection

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25
Q

Stabilizing selection

A

Extreme phenotypes are less successful; average phenotype becomes more common.

26
Q

Directional selection

A

An exceptional phenotype has greater survival and reproduction, causing the population’s mean to shift to one extreme or another.

27
Q

Disruptive selection

A

The average phenotype is less successful than the extreme, and over time the average becomes less common and the population diverges.

28
Q

What was Lamarck’s view on inheritance?

A

Individuals changed to meet the needs of their environment, and acquired characteristics were passed onto offspring.

29
Q

What was Darwin’s view on inheritance?

A

Through the four postulates of natural selection, variation happens. Selection can only work on variation already present in a population. Acquired traits are not passed on.

30
Q

What was the difference between Lamarck and Darwin’s view on inheritance?

A

Lamarck - acquired traits are inherited

Darwin - acquired traits are NOT inherited

31
Q

Vicariance

A

Some sort of break in gene flow due to some sort of battier (stops gene flow entirely, e.g new mountain ranges or islands)

32
Q

Dispersal

A

Process where species are separated but can still maintain gene flow between populations

33
Q

What causes populations to diverge?

A

Some event that reduces or stops gene flow. (Though natural/sexual selection and genetic drift effects may also contribute).

34
Q

Allopatric speciation

A

Populations split by vicariance are then subject to selection

35
Q

Sympactric speciation

A

Sub-population arises within the parent population and diverges, giving rise to a genetically distinct species

36
Q

What is an example of sympatric speciation/ when might it occur?

A

May occur through reproductive isolation or new resources (one subpopulation uses the new resource, while main population primarily uses old resource).

An example is the introduction of green apples in north america, providing a new resource for apple maggots which have split genetically to match the food source.

37
Q

Central dogma

A

DNA –> RNA –> Protein –>

Replication –>Transcription –> Translation

38
Q

What are Mendel’s laws?

A

Law of:
(1) Segregation–only one of an individual’s two alleles for each gene is passed onto offspring.

(2) Independent Assortment–alleles transmitted independently of each other.

39
Q

Law of segregation

A

Each individual has two alleles for each gene. A parent passes on only one of these two alleles to their offspring.

XY ——-> X or Y is passed on.

40
Q

Law of independent assortment

A

Alleles are transmitted independently of one another.

41
Q

Dihybrid cross

A

SsYy x SsYy –> phenotypes: 9 SY: 3 Sy : 3 sY : 1 sy

42
Q

Hardy Weinberg Equilibrium Model

A

Mathematical model to predict allele frequencies in the absence of evolutionary forces.

43
Q

What are the assumptions of the Hardy Weinberg equilibrium model?

A

(1) Random mating
(2) No mutation
(3) Large population size
(4) No migration
(5) No natural selection

44
Q

Migration

A

The regular cyclical movement of a species through its environment (moves back and forth)

45
Q

Dispersal

A

The permanent movement of individuals from parental habitat to somewhere else (unidirectional)

46
Q

Open Population

A

Populations without barriers to dispersal. Individuals travel broadly over large geographic distances.

47
Q

Connectivity

A

The demographic and genetic exchange of material facilitated by dispersal.

48
Q

Closed populations

A

Populations characterized by “self-recruitment” with little or no exchange with outside populations. No connectivity

49
Q

Mutation

A

Random changes in the DNA of an organism that can have varying degrees of effects on the function and/or product of a gene.

50
Q

Genetic Drift

A

The random change in the frequency of alleles in a population, not influenced by the environment or behavior, but by chance (e.g. Founder’s effect, bottleneck)

51
Q

What is the difference between Founder’s effect and bottleneck effect?

A

Founder’s effect is moving to a new habitat, whereas bottleneck effect occurs in the same habitat.

52
Q

What factors influence phenotype?

A

(1) Genotype - genetic makeup of individuals
(2) Environment - local conditions can sway plasticity
(3) Noise - unexplained developmental quirks

53
Q

What drives/influences heritability?

A

Genetic variation (Vg) and phenotypic variance (Vp)

54
Q

What are the factors contributing to phenotypic variance?

A

Genetic (Vg) and environmental (Ve) effects.

55
Q

What is an equation describing the forces that drives heritability?

A

h^2 = Vg / (Vg + Ve)

56
Q

How does increased genetic variation affect heritability?

A

Increases

57
Q

How does increased environmental variation affect heritability?

A

Decreases

58
Q

What are the types of heritable traits?

A

(1) Discrete

(2) Quantitative

59
Q

Discrete trait

A

A trait where you receive one of two/several distinct forms (e.g. blood type)

60
Q

Quantitative

A

A trait that has a continuous distribution (e.g. height)

61
Q

What kind of heritable trait contributes to phenotypic plasticity?

A

Quantitative traits

62
Q

Compare adaptation with evolution

A

Adaptation = species maintains plasticity to survive in a range of habitats (temporary)

Evolution = tied to speciation, formation of discrete, separate unit (more permanent)

BIOL 360 - General Ecology (12 decks)

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