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Evolution - BIOL*2400 > Midterm 2 - Review > Flashcards

Midterm 2 - Review Flashcards

1
Q

Nc is…

A

The census population size (number of elephants in the isolated population that you count).

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2
Q

Ne is…

A

The effective population size is the size of an ideal population that would undergo the same amount of genetic drift (loss of heterozygosity per generation)

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3
Q

Ne > 50 prevents…
Ne > 500 prevents…

A

Ne > 50 prevents severe inbreeding.
Ne > 500 prevents severe loss of alleles from drift.

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4
Q

T or F: Inbreeding alone does not change allele frequencies?

A

True

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5
Q

Why do small populations lose genetic variation?

A

Due to the issue sampling from a small gene pool leading to rate of loss proportional to Ne

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6
Q

Why do small populations decline in mean fitness caused by inbreeding?

A

Mating between close relatives that carry the same deleterious recessive allele, result in more homozygous recessive genotypes and lowers fitness.

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7
Q

Hardy-Weinberg Theorem

A

Predicts that no evolution will take place between generations in the absence of the evolutionary mechanisms: genetic drift, selection, mutation, non-random mating and migration.

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8
Q

What is population subdivision: Fst

A

Reduction in heterozygosity in local populations caused by genetic drift and inbreeding.

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9
Q

Fitness

A

The reproductive success of an individual with a particular phenotype

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10
Q

What are the 3 components of fitness?

A
  1. Survival to reproductive age
  2. Mating success
  3. Fecundity
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11
Q

Relative fitness, w

A

Genotype with highest absolute fitness, wmax = 1. Fitness of all other genotypes standardize by dividing by wmax.

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12
Q

When fitness effects oppose each other, what determines the direction of selection?

A

environment

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13
Q

True or False:
1. Population size influences power of drift and weak selection
2. Drift is more powerful in large populations
3.Selection is more powerful in large popualtions

A
  1. True
  2. False
  3. True
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14
Q

What are the 5 drivers of evolution?

A
  1. Mutation
  2. Non-random mating
  3. Gene flow
  4. Genetic drift
  5. Natural selection
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15
Q

Which factors produce the variation that make evolution possible?

A
  1. Mutation
  2. Non-random mating
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16
Q

Which factors alter a population’s genetic composition

A
  1. Gene flow
  2. Genetic drift
  3. Natural selection
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17
Q

T or F: small populations have lower heterozygosity than the total metapopulation

A

True

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18
Q

T or F: Most fit genotype depends on environment?

A

True

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19
Q

Intrasexual Selection

A

Males fight over females

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20
Q

Ansiogamy

A

Differences in the size of gametes between sexes results in differential investment in reproduction

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21
Q

What may explain the difference in parental care between sexes?

A

Uncertain paternity
2. females have certain parentage and are investing in their offspring or those of their relatives.
3. Males have uncertain paternity and could be directed toward offspring not their own.

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22
Q

Operation sex ratio

A
  • Investment differences between sexes can extend past fertilization.
  • Sex that invests more will be in shorter supply.
  • Ratio of males to females available for mating at a given time
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23
Q

Male-biased OSR

A
  • Slower rate of reproduction by females often leads to male-biased OSR
  • Highest when OSR when female is pregnant or lactates for long periods of time and male does not assist with offspring care
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24
Q

Female-biased OSR

A
  • High ratio of sexually active males to fertilizable females
  • Low ratio of males willing to accept eggs to females who despite male to incubate them.
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25
Q

Early sexual selection definition

A

Depends on the advantage that certain individuals have over the same sex and species, in exclusive relation to reproduction

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26
Q

What is the Bateman 1947 hypothesis?

A

Strength of sexual selection stronger on males

If females show greater reproductive investment than males then:
1. Male reproductive success highly variable and a function of how many copulations he obtains
2. Female reproductive success a function of the food and other resources she can obtain and not of the number of matings that she has

27
Q

which two predictions are now recognized as partially incorrect

A
  1. Males should compete among themselves for opportunities to mate and be promiscuous
  2. Females should be choosy about male they copulate with
28
Q

T or F: Sexual selection is usually stronger on males?

A

True
- male biased OPR
- Maximize fitness by mating with multiple females

29
Q

Intersexual Selection

A
  • Females choose the prettiest/ strongest males because of male biased OSR
  • may choose because of quality or quantity of resources provided by mate
  • may choose based on traits that display male fitness
30
Q

How is Intrasexual selection similar to natural selection?

A
  • Variation in trait within a population
  • Variation must be heritable
  • Individuals with certain trait values have more offspring than other individuals with trait values
31
Q

How is intrasexual selection different from natural selection?

A
  • Traits affect an individual’s ability to obtain matings, which means that individuals of the same sex affect each others reproductive success
  • Members of one sex compete against other members of the same sex, instead of against all other individuals in the population
  • Some teait vaules decrease their possessor’s lifespan
32
Q

Sexual Dimorphism

A
  • The size difference between males and females
  • sexes of the same species exhibit different morphological characteristics
33
Q

Why do females typically prefer larger flashyer males?

A

This shows that they are healthy and therefore will pass good genes to their offspring

34
Q

Infanticide

A

Males will kill existing babies to allow females to come into heat sooner (ex. lions)

35
Q

What are 7 examples of post copulation competition?

A
  1. Mate guarding
  2. Mate guarding by groups of males
  3. Vagina plug
  4. Sperm removal
  5. Sperm production
  6. Faster sperm
  7. Semen toxic to other males sperm
36
Q

What are some reasons females copulate with multiple males?

A
  1. She wants to enter your sperm in a competition
  2. She wants you to think that you might be the father
  3. She ran out of stored sperm
  4. Her other lovers were sterile
  5. Other lovers had incompatible genes
37
Q

Why should females not copulate with multiple males?

A
  • If he catches her with another male her mate might not help rear and defend her children
  • Too much sperm might clog up her reproductive tract making it difficult to lay eggs
  • STD
  • It might be better to spend time foraging so that she can produce even more eggs
38
Q

Avoid creating hybrid offspring hypothesis

A
  • Females chose males with elaborate traits to reduce their risk of mating with the wrong species (modern evolutionary synthesis)
39
Q

Direct Benefits

A

Benefit the choosing mate (usually female) directly (immediatly)

40
Q

Indirect benefits

A

Benefits that affect the genetic quality of the choosing mate’s (usually female) offspring

41
Q

How does female choice evolve when there is a direct benefit to female?

A
  1. Food resources controlled by males
  2. Nest territories defended by males
  3. Competency of paternal care
42
Q

How does female choice evolve when there is no immediate benefit to female?

A
  1. Good genes (healthy male)
  2. Sensory exploitation hypthesis
    - males that look like food
    - males are easy for females to see
  3. Fisherian runaway selection
43
Q

Life-time Fitness

A

Field studies have demonstrated that it is feasible to measure fitness in natural populations by measuring survivorship, mating success and fertility. Number of grandchildren produced by an individual during its lifetime and afterwards

44
Q

What is an example of cryptic female choice

A

Female fowl eject sperm of subdominant males

45
Q

Reversed sex roles leads to … in intersexual selection

A

males choosing

46
Q

Polygenic Trait

A

Influenced by many genetic loci

47
Q

Quantitative genetics

A

Study of the genetics and genomics of continuous phenotypic traits

48
Q

Phenotypic plasticity

A

Variation in the phenotype due to environmental factors

49
Q

Selection

A

Differential survival/fecundity of some phenotypes

50
Q

Migration

A

Movement of individuals and genes from one local population to another

51
Q

Selection Differential

A

measures the strength of directional selection

52
Q

Phenotypic Varience

A

Vp dispersion (spread) of measurable trait resulting from an interaction between its genotype and its environment. Stabilizing and disruptive selection can change Vp

53
Q

Heritability

A

h^2 the proportion of phenotypic variation in a quantitative trait that is inherited

54
Q

Actual Selection R

A

offspring mean minus before selection mean = predicted change in trait

55
Q

How much the population changes depends on: (2)

A
  • selection differential
  • heritability
56
Q

Additive genetic varience, Va

A

genetic variance associated with the average effect of substituting one allele for another

57
Q

Environmental Variance, Ve

A

Phenotypic variation caused by the environment

58
Q

Narrow sense heritability

A

Proportion of phenotypic variance explained by additive genetic variation

59
Q

Broad sense heritability

A

Proportion of phenotypic variance explained by total genetic variation

60
Q

Morphological (Linnean) species concept (MSC)

A

Smallest groups derived from a common ancestor with a “morphological gap” between them

61
Q

Biological Species concept (BSC)

A

Groups of interbreeding populations that are reproductively isolated from other such groups

62
Q

Phylogenetic species concept (PSC)

A
  • smallest possible group descending from a common ancestor and defined by synapomorphies
  • species can be recognized using stats on the characters used to estimate the phylogeny
  • useful where observation of matings is not possible
    Problem: need diagnostic traits. Seperate species if more than 3% COI
63
Q

Mayr’s Modes of Speciation I: gradual through populations

A
  1. Allopatric speciation (=different places)
    a. vicariance (geographical barrier)
    b. founder effect (=peripatric)
  2. Parapatric speciation (= connected)
  3. Sympatric speciation (=same place)

Evolution - BIOL*2400 (2 decks)

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