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Flashcards in Natural Selection Deck (19):
0

Nature selects organisms that are...

Adequate enough to grow up (survive), mate and produce offspring

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Natural selection is a ________ process

Non-random

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Natural selection

A nonrandom process by which traits are selected for by nature because they provide some survival benefit

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4 main principles of natural selection

Variation
Overproduction
adaptation
descent with modification

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Variation

In any population not all organisms are the same

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Overproduction

More babies are born than will survive

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Adaptation

Something that the organism has that is beneficial (a trait)

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Descent with modification

The next generation with slightly different characteristics

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Fitness

The measure of survival ability and ability to produce more offspring in the population

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Differential reproduction

Unequal number of offspring produced by breeding pairs of the same species

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Natural selection acts on...

Existing variation and traits that already exist

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3 modes of selection

Directional selection
stabilizing selection
disruptive selection

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Directional selection

1 of 2 extreme phenotypes is clearly favored

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Stabilizing selection

The middle phenotype is favored

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Disruptive selection

Both extreme phenotypes are favored, middle is no good

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Why does sexual selection happen?

Females have a much higher cost of reproduction (more limited than males)

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Types of sexual selection

Intra-sexual selection
Inter-sexual selection

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Intra-sexual selection

Competition among males in a population for reproductive rights with a female

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Inter-sexual selection

Males display certain desirable traits for reproductive rights with a female