Lecture 2 9-08-10

Lecture 2 9-08-10 - Lecture #2 8 September 2010 Key...

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Unformatted text preview: Lecture #2 8 September 2010 Key Concepts in Physiology Comparative physiological studies must test, not assume, the role of adaptation. Other potential evolutionary mechanisms include ) Historical inheritance ) Developmental pattern and constraint ) Physical and biomechanical correlation ) Phenotypic size correlation ) Genetic correlation ) Chance fixation Testable alternatives to adaptation exist, and their consideration greatly enriches our appreciation of the evolutionary process. Adaptation and Its Alternatives Historical Inheritance n organism may possess a character, or trait, simply because it was present in its ancestors. Developmental Pattern and Constraint Alterations early in development may be not be possible without disrupting development. A feature of an organism might best be explained in terms of its development and not in terms of current utility or design. Physical and Biomechanical Correlation Selection will have operated on features of functional importance. Other features will be completely incidental. Phenotypic Size Correlation Characteristics may be extensively correlated within organisms. Genetic Correlation Characters may be genetically correlated. Chance Fixation When the effective population size is small, an allele may increase and may even become fixed in the population by chance alone. The alteration of a sensory or neural response under constant stimulus Uses of Adaptation in Biology Physiological responses to environmental stress General Adaptation Syndrome Continual exposure to environmental stressors (e.g., sustained white noise; sensory overload) causes the adrenal cortex to release glucocorticoid (stress) hormones, which have myriad short-term and chronic effects. Uses of Adaptation in Biology The state of having become familiar with surroundings and conditions Uses of Adaptation in Biology Functional changes in organisms in response to new conditions or environments Uses of Adaptation in Biology A widespread structure or function that is sometimes crucial for existence and necessary for survival, but not evolved in reference to particular environmental circumstances of extant populations. Uses of Adaptation in Biology he process of improvement of fitness in a population of organisms in response to natural selection. Here, adaptation refers to the Darwinian evolutionary process . This is the common evolutionary use of the term adaptation. Individuals with characteristics favored in their environment will reproduce more, and the favored characters will increase in frequency over generations. (Note: the favorability of characteristics, or traits, is not an absolute, immutable unction of the trait but depends on the properties of the trait in the environment....
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Lecture 2 9-08-10 - Lecture #2 8 September 2010 Key...

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