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What is adaptation?
A heritable phenotype that enhances survival and/or reproduction in a current environment.
What is acclimation?
Acclimation is a short-term physiological adjustment to environmental changes, distinct from adaptation.
What are exaptations?
Structures that are currently adaptations but evolved for a different function.
What is an example of an exaptation?
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Which of the following are necessary to demonstrate that a trait is adaptive? (Select all that apply)
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How is adaptation related to complexity?
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What is a Darwinian demon?
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What process produces adaptations?
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Study Notes
Defining Adaptation
- Adaptation has two meanings: a heritable trait enhancing survival/reproduction in a specific environment (maintained by natural selection for its current function), and the evolutionary process (natural selection) producing such traits.
- A trait's current function doesn't necessitate its original evolutionary purpose for that function.
- Example: Succulents storing water is an adaptation to arid environments.
- The Jamaican bromeliad crab chemically engineers its pools for offspring benefits: removing decaying matter to maintain oxygen and adding snail shells for increased pH and calcium. These are adaptations demonstrated experimentally.
Exaptations
- Exaptations are currently adaptive traits that originally evolved for different functions and were later co-opted for their current fitness-enhancing role.
- Exaptation doesn't imply goal-oriented evolution, anticipation of future needs, or pre-determined uses. Natural selection only operates in the context of the current environment.
- Example: Bird feathers – evolved before flight in theropod dinosaurs.
Detecting Adaptation
- Criteria for demonstrating adaptive traits needs to be established.
- Methods: quantifying selection, reciprocal transplants, and the comparative method.
Evolution of Complex Adaptations
- Complex adaptations can evolve gradually through advantageous steps.
- Exaptation can contribute to the evolution of complex adaptations.
- Example: the evolution of the eye.
Constraints on Adaptation
- "Darwinian demon": a hypothetical organism with perfect adaptation that maximises fitness in all areas.
- Factors limiting perfect adaptation (and the absence of Darwinian demons): trade-offs, constraints imposed by development, genetic constraints, and environmental changes.
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Description
This quiz explores the concepts of adaptation and exaptation in evolutionary biology. It covers definitions, examples, and the roles these traits play in survival and reproduction. Understand how traits can evolve and serve different functions over time.
