Quiz 11 Flashcards

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1
Q

What is Evolution?

A

The change in allelie frequency of a population over time.

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2
Q

What is Evolution by Natural Selection?

A

Change in allelie frequenceies of a population over time due to differential reproductive success within the population that is based on heritable variation.

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3
Q

Who contributed to Darwin’s study?

A

Alfred Wallace

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4
Q

What does evolution by natural selection require?

A
  • Differential reproductive success
  • variation: mutations (point & chromosomal) in sexual reproduction (crossing over & independent assortment)
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5
Q

What is fittness?

A

The contribution to genetic makeup of future generations (potential to reproduce).

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6
Q

What does fittness include?

A
  • function of quantity of offspring
  • quality of offspring (their fittness as well)
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7
Q

What are the 4 Modes of Natural Selection?

A

1) Stabalizing Selection
2) Directional Selection
3) Disruptive Selection
4) Balancing Selection

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8
Q

What is the most common mode of natural selection?

A

Stabalizing Selection

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9
Q

Define stabalizing selection

A

The natural selection acts to resist a change in allelie frequencies because the mean phenotype is the most fit. The population DOES NOT evolve.

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10
Q

Define directional selection

A

Natural selection acts to move the mean phenotype towards 1 extreme of the range because that extreme is more fit. It is caused by a change in the environment!

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11
Q

What is an example of directional selection?

A

The European Pepperd Moth:
- Preindustrial Era: Peppered were more likely to survive than dark
- Industrial Era: Dark were more likely to survive (dust and dark smog)

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12
Q

Define disruptive selection

A

Natural selection acts t create 2 or more genetically distinct forms in the population because the mean phenotype is least fit.

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13
Q

What is an example of disruptive selection?

A

Salmon:
- Females build redd and males fight for who mates.
- Mutant male (Jack salmon): drive-by fertalization of some of the eggs. are smaller

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14
Q

Define balancing selection

A

Natural selection acts to maintain genetic diversity in the population by favoring heterozygotes or rare phenotypes.

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15
Q

What is an example of balancing selection?

A

Scale Eating Cichlids: sneak up behind fish and eat their scales (lefty and righty). The rare one is always more fit than the common one.

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16
Q

What are the 4 Mechanisms for Evolution?

A

1) Mutations
2) Gene Flow
3) Genetic Drift
4) Nonrandom Mating

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17
Q

What is gene flow?

A

The movement of alleles into/out of a population

18
Q

What is an example of gene flow?

A

Isle Royale National Park:
- frequency of skeletal abnormalities of wolfs increased since they mated with themselves. When new wolf showed up, the abnormalities decreased for a certain amount of time, but then increased again.

19
Q

What is genetic drift?

A

The loss in genetic variation due to random events that prevent some individuals in the population from reproducing. There are 2 phenomenons

20
Q

What are the 2 phenomenons of Genetic Drift?

A

1) Genetic Bottleneck
2) Founders Effect

21
Q

Define Genetic Bottleneck

A

A large catastrophic event wipes out a lot of genetic variation.

22
Q

What is an example of genetic bottleneck?

A

Northern Elephant Seals:
- 1890: 20 left
- 1970s: 30,000 - 24 genes and NO variation

23
Q

Define Founders Effect

A

The small subset of a population immigrates and forms a new population. The new population is genetically different than the parent population.

24
Q

What is an example of Founders Effect?

A

When the genetic flow reduces genetic differences among popultions
- Year 1:
- f of A1 = 0.90; f of A2 = 0.10
- Goes to -> f A1 and A2 = 0.50
- Year 2:
- f A1 = 0.83; f A2 = 0.17
- Goes to -> f A1=0.67; f A2=0.33

25
Q

What is another example of Founders Effect?

A

Polydactly: many digits (fingers)
- The Amish in Pennsylvania - high of polydactly

26
Q

What are the two phenomena of Non-random Mating?

A

1) Forced Inbreeding
2) Sexual Selection

27
Q

What are the causes of Forced Inbreeding?

A
  • small population, social structure, and limited dispersion. They all lead to Inbreeding Depression
28
Q

What is Inbreeding Depression?

A

The enhanced expression of negative recessive alleles in a population due to inbreeding.

29
Q

Define Sexual Selection

A

Natural Selection that affects the sexes differently - due to the differences in the reproductive potentials of males and females.

30
Q

In females, their R.P is determined by what?

A
  • How many eggs she can make (limited due to energy)
31
Q

In males, their R.P. is determined by what?

A
  • The number of females he mates with
32
Q

How does sexual selection relate to fitness (hint: traits)?

A

Traits that enhance an offspring’s quantity and/or quantity will be favored by natural selection.

33
Q

What are some female traits that enhance quantity?

A
  • short gestation (time from fertilization to birth)
  • reproductive anatomy
  • size
34
Q

What are some female traits that enhance quality?

A
  • forging behaviors (health)
  • immune system
  • mate choice -> main thing
35
Q

What are some male traits that enhance quantity and quality?

A
  • Promiscuity
  • Being attractive
  • competitive ability
36
Q

What is Sexual Dimorphism?

A

The occurrence of non-gonadal differences between males and females. There are three versions

37
Q

What are the 3 versions of Sexual Dimorphism?

A

1) Females are larger than males (female fecundity increases with size)
2) Males are larger/weapons: male vs. male competition for access to females
3) Males exhibit: elaborate secondary sexual characteristics (female chooses male)

38
Q

Define Fecundity

A

The number of eggs produced in reproduction

39
Q

What does ESSC stand for?

A

Elaborate Secondary Sexual Characteristics

40
Q

What is the Handicap Hypothesis?

A

The ESSC’s serve as a reliable indication of the quality of the male genes. Natural selection favors females that prefer the bright/bold traits.

41
Q

What is the Sensory Exploitation Hypothesis?

A

The ESSC’s evole because they take advantage of an innate preference that is related to some non-reproductive contexts.

42
Q

What are some examples of Sensory Exploitation Hyp.?

A

1) Red-winged Blackbird: males have red patches on their wings, which attracts females since it reminds them of their favorite food.
2) Swordtail: someone cut off the tail of a swordtail fish and glued it onto a platy fish. The females loved the swordtail platy fish.