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16 Cards in this Set
- Front
- Back
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What are 2 reasons evolutionists are interested in development?
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minor changes in regulatory genes can have
major effects on phenotypes – development may constrain morphological evolution |
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Describe the Traditional vs. Recent way that development was described.
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Traditional Studies:
Description of morphology and embryology More recently: Molecular biology is revealing how genes effect development |
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Define:
Individualization |
The process by which an evolutionary characteristic (previously repeated) becomes unique for an organism
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What are 3 organism example structures that are uniform and repeated, and develop into the same form.
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1) Legs in some insects
2) Leaves of a tree 3) Teeth in reptiles |
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Individualization often comes about from _____.
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...dissociation.
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Define:
Dissociation |
Evolutionary change in development where features acquire more independent genetic control.
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Dissociation helps species to...
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...evolve more independently.
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Give an example for how dissociation can allow for a greater amount of traits.
What is this type of evolution called? |
Example:
If bill length and bill thickness are under the same genetic control, selection for larger bill length will result in thicker bills. If bill length and bill thickness are dissociated, can have a greater variety of bill shapes. This is called: Mosaic Evolution |
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Define:
Heterochrony |
An evolutionary change in the timing or rate of developmental events.
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Define:
Allometry |
How characters grow at different rates.
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What was the example of allometry used?
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How the (human) head grows at a slower rate than the rest of the body from birth to adulthood.
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How many characters can undergo heterochronic changes?
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Heterochronic changes can affect many characters at once,
or only a few characters. |
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Define:
Development |
The means by which genetic change is translated into phenotypic change.
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What are:
HOX Genes? |
- Regulatory genes
- each controls the transcription of numerous other genes - do not encode structures, they provide positional information - they tell a cell where it is at in the body. |
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What was the result of evolutionarily increasing the number of HOX genes?
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Increasing the number of Hox genes may have permitted greater morphological complexity in vertebrates.
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Describe how the rate of evolution for Hox genes is related to the genes they control.
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Hox genes change little while their target genes evolve dramatically.
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