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Bio 94: Exam 1 > Chapter 23: How Species Evolve: Macroevolution > Flashcards

Chapter 23: How Species Evolve: Macroevolution Flashcards

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1
Q

What is microevolution?

A

The change of allele frequencies within a population over time

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2
Q

What 3 things can microevolution result from?

A

Natural Selection
Genetic Drift
Gene Flow

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3
Q

What is macroevolution?

A

Evolution that happens on a large scale, above the level of species.

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4
Q

What are the 3 types of mutation and what are their effects on a species?

A

Neutral Mutation

- effect is neither good or bad
- just varying genetic makeups

Deleterious

- bad effects 
- DNA mutation encodes for a different protein that harms the species

Beneficial

- good effects 
- DNA mutation encodes for a different protein that benefits the species
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5
Q

The effects of the mutations on the survival and reproduction of organisms is the basis of ________ ____________.

A

Natural selection

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6
Q

What is a gene pool?

A

The collection of alleles of each individual in an interbreeding population

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7
Q

What does a large gene pool indicate?

A
  • High genetic diversity

- Increased fitness/survival

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8
Q

What does a small gene pool indicate?

A
  • Low genetic diversity

- Decreased fitness/survival

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9
Q

What is the Hardy-Weinberg Equation?

A

p^2 + 2pq + q^2 = 1

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10
Q

What is the Hardy-Weinberg Equation used for?

A

Testing whether evolution is occurring in a population or not

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11
Q

What is a population?

A

A localized group of interbreeding individuals

Consists of one species only

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12
Q

What is allele frequency?

A

How common an allele shows up in a population

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13
Q

What does it mean if a population is in Hardy-Weinberg Equilibrium?

A
  • It means the allele and genotype frequencies in a population are constant.
  • No evolution is occurring.
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14
Q

What does it mean if a population is not in Hardy-Weinberg Equilibrium?

A
  • It means the allele and genotype frequencies in a population are not constant.
  • Evolution is occurring.
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15
Q

Generation 1 looks like this:
BB, Bb, bb, BB, bb, Bb, bb, bb, bb, bb.

  1. What are the genotypes?
  2. What are the genotypic frequencies?
  3. What is the allele frequency?
  4. What is the expected genotypic frequency in Generation 2?
A
  1. 2 BB
    2 Bb
    6 bb
  2. 20%
    20%
    60%
  3. 6/20 x 100% = 30%
    => B = 0.314/20 x 100% = 70%
    => b = 0.7
  4. (0.3)^2 + 2(0.3)(0.7) + (0.7)^2 = 1
    p^2 = 9% BB
    2pq = 42% Bb
    q^2 = 49% bb
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17
Q

There are 100 cats.
84 are black, 16 are white.
White is homozygous recessive.

Determine p^2, 2pq, and p^2.

A

If white is homozygous recessive, then B = Black and b = white.

q^2 is equivalent to bb = 0.16
Therefore, q = 0.4

p is equivalent to 1 - q,
Meaning that p = 1 - 0.4
p = 0.6

Therefore:
p^2 = 0.36
2pq = 0.48
q^2 = 0.16

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18
Q

What would a punnet square representation of the H-W Equation look like?

A 
B=0.6  b=0.4
           |  BB   |   Bb
B=0.6  | 0.36 |  0.24
           |   Bb  |  bb
b=0.4  | 0.24 | 0.16
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19
Q

If p and q values are determined and look like this:

p^2 = 0.36
2pq = 0.48
q^2 = 0.16

And you are given a sample data that shows:

p^2 = 0.20
2pq = 0.64
q^2 = 0.16

What is the explanation for the inconsistency?

A

Evolution has occurred

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20
Q

What are the 5 conditions of the H-W Equilibrium?

What rules must be in order for a population to be in H-W Equilibrium?

A
  1. No Mutations
    • the gene pool has not deleted or duplicated any alleles
  2. Random Mating
    • mating is completely random
    • no sexual selection
  3. No Natural Selection
    • all traits must equally aid in survival
    • no environmental changes
  4. Extremely Large Population Size
    • no genetic drift can occur
    • if population is small, allele frequencies are more likely to fluctuate
  5. No Gene Flow
    • no alleles are being added or removed to the population
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21
Q

What happens if one of the conditions for the H-W Equilibrium is not met?

A

Evolution occurs

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22
Q

Evolution is a change in _____ _______ in a population over time.

A

Allele frequency

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23
Q

What can change allele frequencies?

A
  1. Genetic Drift
    > Founder Effects
    > Bottleneck Effect
  2. Gene Flow
  3. Mutation
  4. Natural Selection
24
Q

What is Genetic Drift and what are the two types?

A

Genetic Drift - when allele frequencies change randomly

  1. Founder Effects
    • a few individuals become isolated and form a new population who’s gene pool is different from that of the original population
    • this happens at the result of migration of a small group, not the survival of a small group
  2. Bottleneck Effect
    • a sudden reduction in the number of alleles present in a population
    • due to environmental change
25
Q

What is Gene Flow?

A

When fertile members move in and out of a population, either adding or removing certain alleles.

26
Q

When humans used to be more isolated in their countries and large populations of them gradually moved to America, alleles have been transferred.
Which method of change to allele frequency has occurred?

A

Gene Flow

27
Q

What is mutation?

A

When deletions, insertions, or exchanges of nucleotides occur.
New alleles are introduced.

28
Q

What is Natural Selection?

A
  • Reproduction of the fittest
  • When a species is better adjusted to an environment and reproduces more
  • The ones that are not better adjusted will not reproduce as much (because they are not the fittest) and may eventually die out
29
Q

What are the effects on genetic variation with respect to:

  1. Genetic Drift
  2. Gene Flow
  3. Mutation
  4. Natural Selection
A
  1. Genetic Drift
    • decreases
  2. Gene Flow
    • increases if alleles are added
    • decreases if alleles are removed
  3. Mutation
    • increases
  4. Natural Selection
    • if Directional/Stabilizing
      > decreases
    • if Disruptive/Balancing
      > increases
30
Q

What are the 5 types of Natural Selection?

A
  1. Directional
  2. Stabilizing
  3. Disruptive
  4. Balancing
  5. Sexual
31
Q

What is Directional Selection?

A
  1. Directional
    • when conditions favor individuals that have one extreme of a phenotypic range
    • E.g. Beak length for specific birds in order to eat.
32
Q

What is Stabilizing Selection?

A
  1. Stabilizing
    • when conditions disfavor both extremes of phenotypic characteristics and favor the in between phenotype
    • E.g. Human baby weight, too big or too small usually die, but a medium sized baby is just right.
33
Q

What is Disruptive Selection?

A
  1. Disruptive
    • when conditions favor both extremes of phenotypic characteristics
    • E.g. In a bird population, there are fruits that require long and short beaks to eat. The birds with the medium beak length cannot easily eat any of the fruit, so they die off, leaving the long-beaked and short-beaked to survive.
34
Q

What is Balancing Selection and what causes it?

A
  1. Balancing
    • when two or more phenotypic forms (BB and bb) remain stable in a population

Caused by:
- Heterozygote Advantage
> Bb has both, therefore more advantaged than the homozygous Dom. and Rec.
- Frequency-dependent Selection
> BB has advantage in one environment
bb has advantage in other

35
Q

What is Sexual Selection and what are the two types?

A
  1. Sexual
    • when phenotypic traits remain or are enhanced due to how many offspring are produced (how likely they are to mate)

Intrasexual Selection
- when individuals of the same sex are constantly competing for the opposite sex

Intersexual Selection
- when females are very picky over their mate’s appearance, even if it risks getting attacked by predators.

36
Q

What is intrasexual Selection?

A
  • when individuals of the same sex are constantly competing for the opposite sex
  • this allows for phenotypic change amongst one sex (e.g. males) depending on which characteristics the females favor
37
Q

What is intersexual selection?

A
  • when females are very picky over their mate’s appearance, even if it risks getting attacked by predators.
  • this allows for phenotypic change amongst males depending on what the females are attracted to
  • e.g. peacocks are very visible to predators, but their colorful display allows them to reproduce at a faster right and is more beneficial to survival than the threat of becoming prey
38
Q

What’s an example of frequency-dependent selection?

A

The grey fish that are either right-mouthed or left-mouthed.

39
Q

What is sexual dimorphism?

A

A distinct difference in appearance between males and females of the same species.
- not directly associated with the ability to reproduce or survive

40
Q

What is diploidy?

A

In diploid eukaryotes, a lot of genetic variation cannot be seen because it is hidden in recessive alleles.

41
Q

What is relative fitness?

A
  • an individual’s contribution to the gene pool of the next generation
  • the success of an organism’s genes being passed on
42
Q

If an organism has great reproductive output, do they have high or low fitness?

A

High

43
Q

If a black cat has 2 kittens, and a white cat has 12 kittens, but 11 of the white kittens die, which cat has higher fitness?

A

Black

44
Q

What is a selective force and what are some examples?

A

Selective force is the environmental factors that affect how successful a species is at surviving (reproducing)

E.g., earthquakes, floods, new food source, asteroids etc

45
Q

What are some helpful questions to consider when deciding if evolution has occurred or not?

A
  1. Is there a variation in the population?
  2. Is the variation heritable?
  3. Was there a selective force?
  4. What there differential reproductive success?
    • did some species not get the chance to reproduce?
46
Q

What is neutral variation?

A

Genetic variation that does not confer a selective advantage or disadvantage

47
Q

How does diploidy help to preserve genetic variation?

A

It allows recessive alleles (that may not be favored in the current environment) to be preserved in the gene pool.

48
Q

How does heterozygote advantage preserve genetic variation?

A
  • Heterozygote advantage is when heterozygotes (possessing both the dominant and recessive allele) have more reproductive success than the homozygous.
  • Heterozygotes continue to pass on recessive alleles.
  • Therefore, the heterozygotes preserve genetic variation as they are more likely to survive and reproduce more, while constantly keeping a recessive allele in the gene pool.
  • e.g. Sickle cell anemia
49
Q

How does frequency-dependent selection preserve genetic variation?

A

In frequency-dependent selection, individuals compete to survive based on their varying alleles.

E.g. Scale-eating fish.
- after a while the left mouthed fish have a lower food source, and the right mouthed fish will reproduce more (and vice versa).

50
Q

The common phenotype is not necessarily the most adaptive. Why?

A

The common phenotype is usually based off of the current environment.
For example, brown cuttlefish may be common at a time because the environment is brown. If the environment becomes greener, predators can target the brown cuttlefish easier and the green cuttlefish will adapt and become the most common because they are better hidden in the environment.

51
Q

What does adaptation mean?

A

The adjustment in an organism to become more suited to an environment

52
Q

Explain the soapberry bug example

A
  • Soapberry bugs in Southern Florida feed on the balloon vines with long beaks.
  • In Central Florida, balloon vines became rare and soapberry bugs started feeding in the Goldenrain tree fruit, which requires a shorter beak.
  • As a result, the soapberry bugs in Central Florida evolved due to their change in food source. (However, they are still the same species)
52
Q

Is the soapberry bug example an example of microevolution or macroevolution?

A

Microevolution

53
Q

Describe the general model for the evolution of resistance?

A
  1. Before selection
    • diverse population with different resistance level alleles
  2. After selection
    • drug introduced to kill off population
    • population with high resistance levels survive
  3. Final population
    • remaining population reproduced and now entire final population has high resistance

Bio 94: Exam 1 (5 decks)

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