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Anp120 - Anp120 Chapter1 Adaptations a feature of an...

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Anp120 Chapter1 Adaptations--- a feature of an organism created by the process of natural selection. Natural selection--- the process that produces adaptation. Natural selection is based on three postulates: 1) the availability of resources is limited; 2) organisms vary in the ability to survive and reproduce; and 3) traits that influence survival and reproduction are transmitted from parents to offspring. When these three postulates hold, natural selection produces adaptation. Morphology--- the form and structure of an organism; also a field of study that focuses on the form and structure of organism. Equilibrium--- a steady state in which neither gene frequencies nor genotypic frequencies change. Stabilizing selection--- selection pressures that favor average phenotypes. Stabilizing selection reduces the amount of variation in the population but does not alter the mean value of the trait. Traits--- a characteristic of an organism. Characters--- a trait or attribute of the phenotype of an organism. Species--- a group of organisms classified together at the lowest level of the taxonomic hierarchy. Biologists disagree about how to define a spices. Fecundity--- the biological capacity to reproduce. In humans, fecundity may be greater than fertility( the actual number of children produced) when people limit family size. Continuous variation---phenotypic variation in which there is a continuum of types, Height in human is an example of continuous variation. Discontinuous variation--- phenotypic variation in which there are a discrete number of phenotypes with no intermediate types. Pea color in Mendel’s experiments in an example of discontinuous variation. achondropasia--- a genetic disease caused by a dominant gene that leads to the development of short stature and disproportionately short arms and legs. convergence--- the evolution of similar adaptations in unrelated species. The evolution of camera-type eyes in both vertebrates and mollusks in an example of convergence.
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placental mammals--- a mammal that gives birth to live young that developed for a period of time in the uterus and were nourished by blood delivered to a placenta.
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