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BIOL1115 LECTURE > Chapter 22,23 > Flashcards

Chapter 22,23 Flashcards

1
Q

what is a species?

A

organisms that can interbreed in nature

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2
Q

what is a gene pool?

A

all the alleles present in all individuals in the same species

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3
Q

what is a population?

A

interbreeding group of organisms of the same species living in the same geographical area

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4
Q

what is evolution?

A

the change in allele/genotypic frequency in a population over time

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5
Q

what is fitness?

A

the relative reproductive ability of an individual

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6
Q

what is a monophyletic group?

A

a group of organisms that descended from the same common ancestor

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7
Q

what is adaptation?

A

inherited traits that were shaped by natural selection and that promote survival and reproduction

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8
Q

what can cause changes in allele/genotype frequencies?

A

factors such as mutations, gene flow, genetic drift, natural selection, and nonrandom mating

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9
Q

What does genetic variation in a population depend on?

A

the rates of occurrence of the alleles in the population i.e allele frequency

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10
Q

how do mutations cause changes in allele/genotype frequencies?

A

creates new alleles through random nucleotide changes and recombination of genetic info

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11
Q

how does gene flow cause changes in allele/genotype frequencies?

A
  • adds new alleles into populations they move into
  • changes the frequencies of alleles already present in the population
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12
Q

How has gene flow become an important agent of evolutionary change in human populations?

A

increase in human migration (i.e gene flow) has led to mating between dissimilar populations, causing the exchange of alleles and fewer genetic differences between those populations (amalgamation)

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13
Q

how does natural selection cause changes in allele/genotype frequencies?

A

certain individuals have better fitness than others and these individuals with their genotypes produce more offspring, therefore leading to adaptation

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14
Q

what does natural selection require for it to cause evolution?

A

a diverse population is needed for differential survival and reproduction to occur, a population of clones will have same fitness all around and will therefore be unable to adapt and evolve

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15
Q

what is natural selection?

A

differential survival and reproductive success between individuals

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16
Q

When can natural selection lead to evolution?

A

If genotypes differ in average fitness, then some genotypes that have better fitness relative to others will contribute more alleles to future generations

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17
Q

what are the three patterns of natural selection?

A
  • stabilizing
  • directional
  • disruptive
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18
Q

what is stabilizing selection?

A

natural selection that selects against the extreme phenotypes/ selects for the mean

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19
Q

what is directional selection?

A

natural selection that selects against one of the two extreme phenotypes

20
Q

what is disruptive selection?

A

natural selection that selects against the mean/ selects for the extremes

21
Q

Why does disruptive selection have the potential to create new species?

A

disruptive selection drives the extremes of a population apart, leading to speciation because of the divergence and isolation between the two extremes.

22
Q

what is artificial selection?

A

successful genotypes are selected by the breeders (usually humans), not by nature or by competition

23
Q

what form of selection is artificial selection?

A

Directional selection because artificial selection selects against one of the extremes and selects for the other

24
Q

what is sexual selection?

A

a form of natural selection in which individuals with certain characteristics are more likely to mate and reproduce than other individuals (more attractive)

25
Q

what is sexual dimorphism?

A

when males and females show distinctly different appearances

26
Q

How does sexual selection lead to sexual dimorphism?

A

the more attractive organisms are able to pass on their alleles to their offspring while the less attractive ones die off

27
Q

What form of selection can counteract sexual selection?

A

natural selection, more attractive organisms may have decreased fitness in order to be more attractive to opposite sex

28
Q

How does genetic drift cause changes in allele/genotype frequencies?

A

some individuals may by chance leave behind more descendants (and genes) than other individuals

29
Q

why are small populations more susceptible to genetic drift?

A

small populations have less individuals to randomly sample alleles from

30
Q

what are the two forms of genetic drift?

A
  1. Founder Effect
  2. Population Bottleneck
31
Q

what is the founder effect?

A

a small group leaves a large population and starts a new population, with random genes and alleles present in the new population that doesn’t necessarily represent the allele/genotypic frequency of the large population

32
Q

what is population bottleneck?

A

a large population shrinks to a small number of individuals by chance (mass death, natural disaster) which reproduce to repopulate

33
Q

why can genetic drift lead to loss of genetic variation?

A

genetic drift causes allele frequencies to change at random, meaning some alleles can be lost no matter they have on fitness

34
Q

How does nonrandom mating cause changes in genotype frequencies?

A

nonrandom mating leads to nonrandom allele combinations, changing the population’s genetic structure

35
Q

what are the types of nonrandom mating?

A
  1. Assortative mating
  2. Disassortative mating
36
Q

what is assortative mating?

A

mating between parents that are genetically or phenotypically similar, leading to offspring being genetically similar

37
Q

what is disassortative mating?

A

mating between parents that are genetically or phenotypically different, leading to offspring being genetically different

38
Q

How does nonrandom mating affect a population’s genetic structure?

A
  • assortative mating leads to excess homozygotes
  • disassortative mating leads to excess heterozygotes
39
Q

explain how diversity is impacted by mutations

A

increases diversity within populations

40
Q

explain how diversity is impacted by gene flow

A

increases diversity within populations

decreases diversity between populations (amalgamation)

41
Q

explain how diversity is impacted by natural selection

A

usually decreases diversity within populations (adaptation)

can increase or decrease diversity between populations (speciation, convergent evolution)

42
Q

explain how diversity is impacted by genetic drift

A

decreases diversity within populations

increases diversity between populations (speciation)

43
Q

what is the Hardy-Weinberg equilibrium?

A

type of equilibrium in populations that have constant allele and genotype frequencies from generation to generation because they are not evolving

44
Q

what are the conditions for a population to be in Hardy-Weinberg equilibrium?

A

absence of evolutionary influences:

  1. no mutations
  2. no gene flow
  3. no natural selection
  4. no genetic drift
  5. random mating

therefore, change will not happen and alleles will combine into genotypes based on the laws of probability

45
Q

what is the Hardy-Weinberg equilibrium good for?

A

if a population is in Hardy-Weinberg equilibrium, we can compute the frequencies of genotypes from the allele frequencies because p and q do not change

46
Q

what is the Hardy-Weinberg equilibrium equation?

A

p + q = 1 (allele frequency)

p² + 2pq + q² = 1 (genotypic frequency)

a population is not at equilibrium if equation does not equal 1

BIOL1115 LECTURE (11 decks)

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