Lecture 4 Flashcards

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1
Q

What is Evolution?

A

The process that results in changes in the proportion of heritable traits within populations from one generation to another

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2
Q

What is Natural Selection

A

The only evolutionary mechanism that leads to adaptions

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2
Q

What are the four forces/mechanisms included in Evolution that drives changes?

A
  • Natural selection
  • Mutation
  • Genetic Drift
  • Gene Flow
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3
Q

What are adaptions?

A

Traits that provide a “fit” between an organism and its environment

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4
Q

What are Medium ground finches and their characteristics?

A
  • One of two finch species living on Daphne island
  • Have stubby beaks
  • Primarily eat seeds
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5
Q

What are medium ground finches with deeper beaks better at?

A

Better at eating large/hard seeds than finches with shallow beaks

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6
Q

Who tracked finches?

A

Peter and Rosemary Grant tracked finches on Daphne Island since 1973

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7
Q

What happened in 1976 on Daphne Island?

A

A major drought hit the island and the distribution of seeds changed over time (there was fewer small/soft seeds than large/hard seeds

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8
Q

What did researchers establish in regards to the finch population?

A

Variation existed in the finch population (beak depth)

Beak depth is a heritable trait

Finches with deeper beaks were more likely to survive and reproduce

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9
Q

What are Darwin’s 3 Postulates?

A
  1. Phenotypic Variation Exists within a Population
  2. Differential reproduction/survival occurs based on that phenotypic variation.
  3. Variation is genetically heritable
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10
Q

What does “Fitness” mean?

A

A term most often used by biologists to explain the evolutionary success of certain organisms.

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11
Q

What is Fitness a measure of?

A

A measure of how many surviving offspring one produces.

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12
Q

What are traits that increase reproduction?

A

Adaptive

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13
Q

What is Directional Selection?

A

Distribution of a trait moves in a single direction
(Example with finches during the drought shows directional selection)

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14
Q

What is Stabilizing Selection?

A

Genetic variants that lead to ‘extremes’
(e.g., deep beaks OR shallow beaks)
become less common in the population
over time
* This can happen when there are trade-offs

  • Reduce/Maintain Variation
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15
Q

What is Disruptive Selection?

A
  • Genetic variants that lead to average beak depth become less common in the population over time – selection favours genetic variants that lead to the ‘extremes’
  • This can happen when it is beneficial to be a specialist
  • Favour more ‘extreme values’
16
Q
A