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biology 11 - intro to organisms - section iv > chapter 17 > Flashcards

chapter 17 Flashcards

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1
Q

all the alleles of all the genes in a population; “genetic resources,” shared by all the members of the population (in theory)

A

the gene pool

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2
Q

infrequent but inevitable changes in genes

A

mutations

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3
Q

mutation is a source of…

A

new alleles/genetic variation

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4
Q

crossing over at meiosis i introduces…

A

new combinations of alleles into chromosomes

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5
Q

independent assortment at meiosis i mixes…

A

maternal and paternal chromosomes

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6
Q

fertilization combines…

A

alleles from two parents

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7
Q

changes in chromosome number or structure occur which are known as…

A

transposition, duplication, or loss of chromosomes

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8
Q

individuals do not evolve, ______________ do

A

populations

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9
Q

frequency of certain ________ is the result of evolution

A

traits

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10
Q

a theoretical state in which an allele’s frequency never changes in a population’s gene pool

A

genetic equilibrium (population is not evolving)

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11
Q

list the five conditions needed for genetic equilibrium

A
  1. mutations never occur
  2. mating is random
  3. the allele does not affect survival or reproduction (i.e., there is no selection for or against that trait)
  4. the population is infinitely large
  5. no immigration or emigration
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12
Q

when comparing a population’s gene pool to a control group, the “null hypothesis” is the population at…

A

genetic equilibrium

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13
Q

at genetic equilibrium, proportions of genotypes at a locus with two alleles will remain the same

A

hardy-weinberg law

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14
Q

what does the hardy-weinberg law/equation state?

A

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

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15
Q

heterozygous genotypes for genetic diseases are known as “__________” for that disease, but remain unaffected themselves

A

carriers

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16
Q

small scale changes (small group, short time) in allele frequencies that drive a population away from genetic equilibrium

A

microevolution

17
Q

the four main components of microevolution are…

A
  1. mutation
  2. natural selection
  3. genetic drift
  4. gene flow
18
Q

a difference in the survival and reproductive success of different phenotypes, not purposeful, it simply fills the nooks and crannies of opportunity

A

natural selection

19
Q

natural selection acts _________ on phenotypes and ___________ on genotypes

A

directly, indirectly

20
Q

a type of selection where one end of the spectrum of phenotypes is favored

A

directional selection

21
Q

a type of selection where the middle ground or “medium” phenotype is favored (extremes are NOT favored)

A

stabilizing selection

22
Q

a type of selection where the extreme phenotypes are favored and (the middle is NOT favored)

A

disruptive selection

23
Q

example of directional selection

A

peppered moths: coloration before, during, and after the industrial revolution

24
Q

example of stabilizing selection

A

birth weight and mortality rates

25
Q

example of disruptive selection

A

the beaks of birds with two types of seeds available (finches?)

26
Q

a type of selection that is due to nonrandom mating; leads to sexual dimorphism

A

sexual selection

27
Q

the term for different sexes having different traits

A

sexual dimorphism

28
Q

the term for the change in the frequency of an existing gene variant in a population due to random chance

A

genetic drift

29
Q

genetic drift is more prominent in __________ populations

A

small

30
Q

when alleles disappear and leave only one possible form of that gene left, it’s known as

A

fixation

31
Q

an effect that is due to a reduction of population size that is so severe it reduces genetic diversity

A

the bottleneck effect

32
Q

an example of the bottleneck effect

A

elephant seal population was hunted down to 14-20 individuals, and is now at 130,000. electrophoresis revealed that there is now no allele variation at 24 genes

33
Q

an effect pronounced on isolated islands; when a small group of individuals start a new population and their gene pool overall differs a lot from the original

A

the founder effect

34
Q

island chains offshore that are prone to speciation

A

archipelagos

35
Q

colonization and genetic divergence lead to…

A

speciation

36
Q

examples of archipelagos

A

the galapagos, the hawaiian islands

37
Q

in absence of other bird species on the hawaiian islands, ____________ radiated to fill numerous niches

A

honeycreepers

38
Q

hawaii is home to ___% of fruit fly species

A

40

39
Q

an effect that tends to keep the gene pools of populations similar; counters the differences that result from mutation, natural selection, and genetic drift

A

gene flow

biology 11 - intro to organisms - section iv (1 decks)

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