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Biology 243 > Topic 3 > Flashcards

Topic 3 Flashcards

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1
Q

natural selection

A

when there is variation within a population and organisms, and when that variation can be inherited, the variants best suited for growth and reproduction in a given environment will contribute disproportionately to the next generation

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2
Q

environmental variation

A

variation among individuals due to differences in environment

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3
Q

genetic variation

A

variation among individuals caused by differences in the genetic material that is transmitted from parent to offspring

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4
Q

“descent with modification”

A

evolutionary changes that have accumulated over time since the two lineages split

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5
Q

species

A

consists of individuals that can exchange genetic material through interbreeding

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6
Q

gene pool

A

all the alleles present in all individuals in the species

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7
Q

individuals represent different combinations of alleles drawn from:

A

the species’ gene pool

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8
Q

population genetics

A

the study of genetic variation in natural populations

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9
Q

population

A

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

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10
Q

what are the two sources of genetic variation?

A

mutation and recombination (synapsis)-produces new alleles

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11
Q

neutral mutations

A

having little or no effect-most common type of mutation because most of genome is noncoding DNA

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12
Q

deleterious mutation

A

harmful effect-most common type of mutation in coding sections of genome

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13
Q

advantageous mutation

A

improves carrier’s chance of survival or reproduction; least likely to occur

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14
Q

which type of mutation allows for adaptation of a species (better able to survive and reproduce in that environment)?

A

advantageous mutation

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15
Q

allele frequencies

A

rates of occurrence of alleles in population: number of allele x present in population divided by total number of alleles

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16
Q

a population is FIXED for that allele

A

=population exhibits only one allele at a particular gene

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17
Q

genotype frequency

A

the proportion in a population of each genotype at a particular gene or set of genes

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18
Q

what are three ways to measure genotype and allele frequencies in populations?

A

observable traits, gel electrophoresis, and DNA sequencing

19
Q

observable traits require:

A

studies of traits/phenotypes that are encoded by a single gene

20
Q

gel electrophoresis was applied to:

A

proteins to focus on enzymes and thus detect genetic variation, but can ONLY study enzymes

21
Q

evolution is:

A

a change in allele OR genotype frequency over time (i.e. a change in the genetic makeup of a population over time)

22
Q

Hardy-Weinberg equilibrium

A

describes situations in which allele and genotype frequencies do not change, they change only when specific forces act on the population

23
Q

requirements to meet Hardy-Weinberg equilibrium:

A
  1. There can be no differences in the survival and reproductive success of individuals
  2. populations must not be added to or subtracted from migration
  3. there can be no mutation
  4. the population must be sufficiently large to prevent sampling errors
  5. individuals must mate at random
24
Q

selection

A

the differential success of alleles

25
Q

genetic drift

A

a change in the frequency of an allele due to the random effects of limited population size

26
Q

non-random mating

A

individuals do not mate randomly, affects genotype frequencies from generation to generation but does not affect allele frequencies

27
Q

the Hardy-Weinberg relation predicts:

A

genotype frequencies from allele frequencies and vice versa

28
Q

what is the starting point for population genetic analysis?

A

the Hardy-Weinberg equilibrium-if population not in equilibrium, we can infer that evolution has occurred.

29
Q

fitness

A

a measure of the extent to which the individual’s genotype is represented in the next generation

30
Q

the Modern Synthesis combines:

A

Mendelian genetics and Darwinian evolution

31
Q

what is the result of natural selection?

A

increased frequency of advantageous mutations (alleles), decreased frequency of deleterious mutations

32
Q

positive selection

A

natural selection that increases the frequency of a favourable allele

33
Q

negative selection

A

natural selection that decreases the frequency of a deleterious allele

34
Q

how can deleterious alleles remain in the population?

A

the genetic disease may occur rarely only in homozygous genotypes, is not selected against when expressed as a heterozygote

35
Q

balancing selection

A

maintenance of an allele at some intermediate frequency between 0-100%, maintains two or more alleles in a population

36
Q

heterozygote advantage

A

an example of balancing selection in which the heterozygote’s fitness is higher than either of the homozygotes, resulting in selection that ensures both alleles remain in the population at intermediate frequencies, ex. malaria

37
Q

stabilizing selection

A

maintains the status quo of phenotypes and acts against extremes; keeps a trait the same over time

38
Q

directional selection

A

leads to a change in trait over time

39
Q

artificial selection

A

a form of directional selection; analogous to natural selection but the competitive element is removed, instead, selection is done by breeder

40
Q

disruptive selection

A

operates in favour of extremes and against intermediate forms, can lead to formation of new species

41
Q

sexual selection increases:

A

an individual’s reproductive success

42
Q

sexual selection

A

promotes traits that increase an individual’s access to reproductive opportunities; phenotypes are generally a trade-off between conflicting demands of reproduction and survival

43
Q

intrasexual selection

A

focuses on interactions between individuals of one sex (ex. males compete with another for access to females)

44
Q

intersexual selection

A

focuses on interactions between females and males (males do not fight one another but compete for attention of female, females choose their mates)

Biology 243 (15 decks)

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