Microevolution II Flashcards

1
Q

Microevolutionary studies

A

examine how processes such as mutation, natural selection, recombination, migration, non-random mating, and genetic drift determine as well as change the genetic composition of populations

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2
Q

5 assumptions of HWE

A
  1. There is no mutation
  2. The population is infinitely large
  3. Mating among individuals is random
  4. Individuals are not moved into or out of population
  5. All individuals have equal probabilities of survival and of reproduction
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3
Q

What 2 processes produce the variation in gene pools that contribute to differences in individuals?

A

mutation and sexual recombination

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4
Q

Synonymous mutations

A

mutations that don’t change the encoded amino acid

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5
Q

Non-synonymous mutations

A

changes in nucleotides that change amino acids

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6
Q

Factors that vary rates of mutation

A
  1. sex
  2. generation time
  3. environment
  4. stress
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7
Q

2 principal ways to not have random mating

A
  1. Assortative mating
  2. Inbreeding
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8
Q

Assortative mating

A

like genotypes mate w/ each other or avoid each other

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9
Q

Inbreeding

A

mating among individuals that are more closely related than those drawn by chance from the population

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10
Q

Positive assortative mating

A

-decreases heterozygosity for the gene affecting the trait
-heterozygotes are decreased by half each generation w/ complete positive assortative mating

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11
Q

Negative assortative mating

A

-increases heterozygosity for the gene(s) affecting that trait

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12
Q

Effect of inbreeding

A

-changes genotype frequencies by increasing the proportion of homozygotes and reduces the proportion of heterozygotes across the entire genome
-most extreme case (selfing): has effects just like positive assortative mating but across the WHOLE genome

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13
Q

Evolutionary consequences of non-random mating

A
  1. The genotype changes caused by assortative mating affect only the loci contributing to the phenotype
  2. The genotype changes caused by inbreeding affect all loci in the genome
  3. Inbreeding results in genome-wide loss of heterozygosity (loss of diversity)
  4. Inbreeding and assortative mating only affect genotype frequencies so their effects may be quite ephemeral or temporary
  5. Inbreeding reduces fitness by generating offspring homozygous for deleterious alleles (inbreeding depression)
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14
Q

Self-fertilizing species typically exhibit _______ levels of diversity

A

lower

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15
Q

Inbreeding depression

A

Inbreeding reduces fitness through the generation of offspring homozygous for deleterious alleles

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16
Q

Genetic drift

A

-basic mechanism of evolution
-evolutionary equivalent of a sampling error
-definition: variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce

17
Q

Long-term patterns of genetic drift

A
  1. population bottleneck
  2. founder effect
18
Q

Population bottleneck

A

when a population goes through a period of unusually small population size
-greatly reduces genetic variation
-many genes may be lost

19
Q

Founder effect

A

when a population does through this period of unusually small population size at a time when it arrives to a new, uncolonized area
-may have a non-random sample of the genes present in the original population and/or reduced genetic variation from the original population
-Ex: Canadian Mennonites

20
Q

5 effects of genetic drift

A
  1. Genetic drift is significant in small populations
  2. Genetic drift can cause allele frequencies to change at random
  3. Genetic drift can lead to loss of genetic variation within populations
  4. Genetic drift can lead to differentiation among populations
  5. Genetic drift can cause harmful alleles to become fixed
21
Q

Gene flow

A

the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes
-can also change allele frequencies