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19 Cards in this Set
- Front
- Back
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Darwin's Postulates vs. the Modern View:
Darwin: Individuals within a species are variable. Modern: ? |
As a result of mutation, segregation, and independent assortment, individuals within a species are variable.
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Darwin's Postulates vs. the Modern View:
Darwin: Some of these variations are passed on to offspring. Modern: ? |
Individuals pass their genes on to their offspring intact and independently of other genes.
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Darwin's Postulates vs. the Modern View:
Darwin: In most generations, more offspring are produced than can survive Modern: ? |
In most generations, more offspring are produced than can survive.
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Darwin's Postulates vs. the Modern View:
Darwin: Survival and reproduction are *not* random: The individuals that survive and go on to reproduce, or who reproduce the most, are those with the most *favorable* variations. They are naturally selected. Modern: ? |
Most favorable variations = alleles and allelic combinations that best adapt them to their environment.
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How do alleles play a part in maintaining beneficial characteristics?
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Alleles associated with higher fitness (i.e. reproductive fitness) increase in frequency from one generation to the next.
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What organism was used as an example for testing each of the 4 modern translations of Darwin's postulates?
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The Medium Ground Finch.
Studied by Rosemary and Peter Grant. |
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How did the 1977 drought show that survival and reproduction were non-random events in the Medium Ground Finch?
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After the drought, there were fewer smaller seeds
Thicker-billed birds were able to crack the larger seeds better. Thus thicker-billed birds were selected *The offspring after the drought had thicker bills than the population before. |
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What are the 3 general patterns/modes of selection?
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1) Directional
2) Stabilizing 3) Disruptive |
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Define:
Directional Selection What's are 2 example organisms? |
Shifting phenotypic and genotypic frequencies.
**One extreme is favored. i.e. a shift of the "hump" on the graph to the right or the left. Examples: 1) Medium Ground Finch - The ones with the thicker-billed beaks were chosen. 2) Peppered Moth - Depending on smog environment, the black or the white moths on trees were favored. |
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The Medium Ground Finch is an example of what type of selection?
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Directional Selection
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The Peppered Moth is an example of what type of selection?
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Directional Selection
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Define:
Stabilizing Selection What is an example organism? |
- Maintains the status quo
- Extremes are eliminated - Assume already well adapted i.e. the *intermediates* are favored. On the graph, the extreme right/left are eliminated. Example: Gall-making fly Fly larvae is inside a flower. The larvae that are inside medium flowers last the longest. |
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The Gall-making fly is an example of what type of selection?
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Stabilizing selection
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Define:
Disruptive Selection Example organism? |
- Selection for both extremes
- Selection against the norm - Generally argued that it is rare to maintain. i.e. on the graph, the middle in eliminated in favor of BOTH extremes EXA: Pyrenestes - Seedcracker Finches. |
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Other than selection, what are the 4 other major evolutionary forces?
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1) Nonrandom mating
2) Mutation 3) Migration 4) Genetic Drift |
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Define:
Selection Describe each term in your answer. |
Nonrandom sorting of heritable characters.
Nonrandom: - Environment recognizes and acts on the variation present in population Sorting: - Separation of characters Of: - ...of Heritable: - Genetically based Characters: - DNA to morphology and behavior |
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Define:
Genetic Drift |
Random sorting of heritable characters.
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What is the main difference between:
Selection and Genetic Drift? |
Selection is NON-random.
Genetic Drift is RANDOM. |
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Genetic Drift:
The _____ the population, the _____ the effect from drift. |
...smaller...
...greater... |
