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Human Biology > Selection > Flashcards

Selection Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Natural Selection

A

Phenotypic variation occurring on a trait due to survival and reproduction of particular traits

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2
Q

What are the four forms of selection?

A

Directional selection
Disruptive selection
Stabilizing selection
Frequency-dependent selection

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3
Q

Is heritability negative or positive for phenotypes under selection?

A

Positive

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4
Q

What is directional selection?

A

Selection occurring in a single directions altering the mean but not changing the variance

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5
Q

What is disruptive selection?

A

No change in the mean

Increases the variance

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6
Q

What is stabalizing selection?

A

No change in mean, decrease in variance

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7
Q

Frequency dependent selection?

A

Survival of one trait depends on who you are around

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8
Q

Negative frequency dependent selection:

A

If the trait is rare it does really well creating a super dynamic system

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9
Q

Positive frequency dependent selection:

A

The more common the trait is, the better it does (eventually becomes fixed)

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10
Q

How does gene flow effect natural selection?

A

NEED TO ASK FRANCO

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11
Q

How does genetic drift effect natural selection?

A

if you have a small population, genetic drift has large effect and causes alleles to go to fixation so no selection is occuring

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12
Q

what does (s) represent?

A

the selection coefficient

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13
Q

What does evolution depend on?

A

The size of the population relative to the selection coefficient

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14
Q

In what case does selection overcome drift?

A

s>1/4Ne

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15
Q

How are advantageous alleles lost?

A

Due to drift if small population because drift is random! This is also how deleterious alleles can become fixed

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16
Q

Does adaptation happen through mutations of large or small effect?

A

Small effect

17
Q

Fishers model

A

Displays why it is easier to get adaptations of small effect mutations because the path to “the best trait” is more controlled

18
Q

What does a selective sweep do to variation?

A

reduce genetic variation near the locus under selection

19
Q

What is a selective sweep?

A

reduction or elimination of variation among the nucleotides in neighboring DNA of a mutation as the result of recent and strong positive natural selection.

20
Q

Candidate Genes

A

those loci hypothesized to be under selection.

21
Q

MC1R: melanocortin-1 receptor

A

The gene that controls skin color. Evolved 1.2 million years ago

22
Q

UVA

A

Degrades folate
Neural tube disorders
Spermatogenesis
Skin cancer

23
Q

UVB

A 
Cholesterol -> vitamin D
Calcium absorption
Immune function
Reduces inflammation
Modulation of cell growth
24
Q

What form of selection is controlling melanin?

A 
Directional? 
Cholesterol -> vitamin D
Calcium absorption
Immune function
Reduces inflammation
Modulation of cell growth
25
Q

How many genes affect skin pigmentation?

A

six

26
Q

Meme

A

an element of a culture that may be passed from one individual to another by nongenetic means, especially imitation.

27
Q

Cultural evolution determine by:

A 
Transmission errors (mutation)
Statistical effects in small populations (drift)
Differential transmission of variants depending upon their utility (selection)
Transmission of variants between populations (migration)
28
Q

Dual Inheritance System

A

The phenotype is determined by genetic and cultural traits

These inheritance systems interact to influence the transmission of genes and memes

29
Q

Niche Construction

A

Cultural evolution alters the environment
Natural selection favors genetic mutations that facilitate the adoption of adaptive cultural practices
Cultural evolution may also constrain genetic evolution, and vice versa

30
Q

Neolithic Transition

A

Farming produces 10-100 times more human-consumable calories per acre than hunter-gathering
Salivary amylase gene (AMY1) CNV

31
Q

Lactose Persistence

A

Prior to the domestication of animals, only mothers provided milk
Lactase is not expressed in adults in other primates and varies among human populations.
Lactase persistence has been proposed to have evolved in response to selection generated by the advent of dairying practices during the Neolithic transition.

32
Q

Which came first – lactase persistence (LP) or dairying?

A

Dairy but only populations with LP can dairy

33
Q

Lactase

A

Enzyme expressed in small intestine

Breaks down lactose into glucose & galactose

Human Biology (14 decks)

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