The Really Evolution Continued

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disruptive selection:

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Selection favoring forms that deviate in either direction from the population average. Selection favors forms that are larger or smaller than average, but works against the average forms between the extremes.

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Balanced Polymorphism -

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A situation in which it is beneficial for a population to maintain two different alleles creating different phenotypes within the population. It’s also a change of shape. Examples such as Sickle Cell Anemia.

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Preadaptation:

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A characteristic evolved by an ancestral species or population that serves an adaptive though different function in a descendant species or population.

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adaptation:

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Any heritable characteristic of an organism that improves its ability to survive and reproduce in its environment. Also used to describe the process of genetic change within a population, as influenced by natural selection.

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Microevolution:

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evolution within a species or population. An increase in a particular gene’s frequency in a population due to natural selection is an example of microevolution.

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Macroevolution:

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can be defined simply as evolution above the species level, and its subject matter includes the origins and fates of major novelties such as tetrapod limbs and insect wings, the waxing and waning of multi-species lineages over long time-scales, and the impact of continental drift and other physical processes on the evolutionary process.

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adaptive radiation:

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The diversification, over evolutionary time, of a species or group of species into several different species or subspecies that are typically adapted to different ecological niches (The ecological role of a species; the set of resources it consumes and habitats it occupies.) (for example, Darwin's finches). The term can also be applied to larger groups of organisms, as in "the adaptive radiation of mammals."

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Quantitative Variation:

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Measured in degrees

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Discrete Variation:

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Control by 1 gene.

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Index fossils:

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(or zone fossils) are fossils used to define and identify geologic periods (or faunal stages). They work on the premise that, although different sediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil. If the species concerned were short-lived (in geological terms, lasting a few hundred thousand years), then it is certain that the sediments in question were deposited within that narrow time period.