EvolInActionLEC13 Flashcards

1
Q

What are the three different ways that natural selection is likely to change populations? (Modes of Selection)

A

Directional, Disruptive, and Stabilizing selection!

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2
Q

What is directional selection?

A

A selection that favors individuals at one end of the phenotypic range.

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3
Q

What is disruptive selection?

A

A selection that favors individuals at both extremes of the phenotypic range.

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4
Q

What is stabilizing selection?

A

A selection that favors intermediate variants and acts against extreme phenotypes.

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5
Q

The normal curve of a phenotypic range is?

A

Normal distribution! or the bell curve!

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6
Q

What is balancing selection?
Ex. leopards & cheetahs
What does it lead to?

A

A selection that occurs when natural selection maintains stable frequencies of 2 or more forms in a population.
Leads to balanced polymorphism

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7
Q

What maintains genetic variation in population in the form of hidden recessive alleles?

A

Diploidy!

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8
Q

What is a heterozygote advantage
What will natural selection tend to do
Ex. sickle-cells in humans

A

Heterozygote individuals have greater fitness than homozygotes for a certain gene. Natural selection tend to maintain two or more of these alleles in the population.
Those who are heterozygote are immune to sickle-cells.

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9
Q

What is frequency-dependent selection?

A

A selection that occurs when the fitness of a morph declines if it becomes too common in the population.

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10
Q

What is sexual selection?
What can this result in?
Ex. Jacana birds.

A

A selection where an individual’s (reproductive success) depend on mating success.
Can result in sexual dimorphism.

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11
Q

What is sexual dimorphism?

A

Distinct differences between the sexes in secondary sexual characteristics.

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12
Q

What is intrasexual selection?

Ex. Two fighting male gazelles

A

Direct competition for mates of the opposite sex.

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13
Q

What is intersexual selection?

Ex. Male’s peacock appeal to female ones.

A

A selection that occurs when individuals of one sex are choosy in selecting their mates.

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