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Evolution > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

Should see 3:1 brachydactylous:wild type in population
Dominant will be selectively advantageous
Or at least take over

A

incorrect beliefs

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2
Q

relative commonness or rarity of alleles

A

allele frequency

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3
Q

genetic variation in sexually reproducing species

A

recombination into heterozygotes or homozygotes

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4
Q

Depends on relative abundances of alleles

A

Genetic Variation

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5
Q

Alterations in gene frequencies in one generation

A

Genetic Variation

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6
Q

Will alter the alleles carried to next generation

A

Genetic Variation

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7
Q

When genotypes have predicted frequencies

A

Hardy-Weinberg Equilibrium

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8
Q

Was the original population in H-W quilibrium

A

Chi Square

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9
Q

Genotype frequencies obtain H-W values after how many rounds of random mating

A

one

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10
Q

If something caused a population to not be in equilibrium

A

One round of random mating would obscure that

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11
Q

Allele frequencies don’t change from one generation to the next so a new mutation would remain rare

A

true

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12
Q

is when populations violate the assumptions of H-W

A

Evolution

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13
Q

H-W assumptions

A
  1. No natural selection- all individuals have equal chances at survival and reproduction.
  2. Mating is random- no sexual selection
  3. No migration
  4. The population is effectively infinite (no changes by chance alone) - No Genetic drift - random change in small populations
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14
Q

a value for how much survival is decreased for a particular phenotype
s

A

Need Selection Coefficient

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15
Q

The larger the selection coefficient is, the stronger the…

A

action of natural selection \

-so when s is a bigger number, the A1 allele approaches fixation earlier.

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16
Q

An allele is consistently favored

A

Directional Selection

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17
Q

Will lead to fixation – will be only allele in population (well, just about at least).

A

Directional Selection

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18
Q

Rate differs whether allele is dominant or recessive

-recessive is slower to reach fixation

A

Directional Selection

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19
Q

Why is directional selection slow when recessive gene is expressed?

A
  • Most A1 are in heterozygotes and phenotype not expressed

- Slow to build up more successful homozygotes

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20
Q

In directional selections this reaches fixation faster

A

Codominant

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21
Q

In directional selections this receives some advantage from the A1 allele

A

Heterozygotes

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22
Q

In directional selections this reaches fixation slower

A

Dominant A1

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23
Q

In directional selections this is hard to remove from a population

A

A2

24
Q

-If A1 is rare, there will be an increase in the gene

I-f it is common, there will be a decrease because more, less fit homozygotes

A

overdominance

25
Q

a stable polymorphism

A

Balancing selection- this is very rare

26
Q

Sickle-cell (S allele vs. A)
AS suffer slight anemia, SS severe anemia
But normal, AA, have higher mortality from malaria
Blood cells of heterozygotes broken down more rapidly limiting chance of survival

A

example of overdominance

27
Q

Heterozygote has lower fitness

A

Underdominance

28
Q

If an allele is rare, it will be lost because most are in heterozygotes
RARER

A

Underdominance

29
Q

Diversifying Selection

A

Underdominance

30
Q

Black-bellied seedcrackers - bimodal distribution of bill depth
Probably not one gene

A

Diversifying Selection

31
Q

Heterozygotes have severe autoimmune disease

A

Underdominance

32
Q

Costs and benefits of a trait depend on how many individuals with such a trait are present in the population

A

Frequency Dependent Selection

33
Q

fitness increases as number of individuals with the trait increase in population.

A

Positive Frequency Dependent Selection

34
Q

Flat Land Snails – mate face to face
Can only mate with snails whose shells coil in same direction
Higher the frequency of either type, the greater the success

A

Positive Frequency Dependent Selection

35
Q

Fitness of a trait decreases as frequency of the trait increases
Scale-eating cichlid Perissodus microlepis attacks from behind
Right-turned (dextral) and left-turned (sinistral) mouths

A

Negative Frequency Dependent Selection

36
Q

Number of offspring produced
May survive fine, but not produce offspring
Crossed wild and domestic sunflowers
-fitness decreased in hybrid!!

A

Fecundity Selection

37
Q

reproduce once and then die

A

Semelparity

38
Q

reproduce more than once

It gets more complex

A

Iteroparity

39
Q

Usually ecologists just count daughters

A

Iteroparity

40
Q

Offspring produced at an earlier age increase fitness more

A

Life History - Population Increase

41
Q

A genotype that reproduces earlier and has a shorter generation time and higher fitness (as measured by r) than a genotype that reproduces later

A

Life History - Population Increase

42
Q 
r  = per capita rate of population increase
R = er
A

Life History

43
Q

If one allele mutates into another

A

the allele will continuously appear in the population

44
Q

Shift from H-W equilibrium

A

Mutation

45
Q

80% are new mutations inherited from one parent

A

Achondroplasia

46
Q

mate with own genotype or phenotype

A

Assortative Mating

47
Q

mate with those of different genotype or phenotype

A

Disassortative Mating

48
Q

gene copies may be identical by descent

A

Inbreeding – Assortative

49
Q

Offspring between closely related individuals have lower fitness

A

Inbreeding Depression

50
Q

increased with inbreeding – people form Croatian islands

A

Hypertension

51
Q

20% of marriages between genetically related individuals

A

Inbreeding Depression

52
Q

Increase in heterozygotes over that predicted by H-W

A

Disassortative Mating

53
Q

Prefer mates with different Major Histocompatibility Complex

A

Disassortative Mating

54
Q

could drastically alter allele frequencies

A

Migration from a large population to a small one

55
Q

Will bring new alleles into a population

A

Migration

Evolution (15 decks)

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