Biology: Chapters 16 & 17-4 Evolution

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Convergent Evolution

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Process by which unrelated organisms independently evolve similarities when adapting to similar environments.

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Adaptive Radiation

Back 2

Process by which a single species or small group of species evolves into several different forms that live in different ways.

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Adaptive Radiation

Back 3

Rapid growth in the diversity of a group of organisms.

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Coevolution

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process by which two species evolve in response to changes in each other.

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Punctuated Equilibrium

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Pattern of Evolution in which long stable periods are interrupted by brief periods of more rapid change.

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Mutation

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Change in a DNA sequence that affect genetic information.

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Gene Pool

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Combined genetic information of all the members of a particular population

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Relative Frequency

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Number of times an allele occurs in a gene pool compared with the number of times other alleles occur.

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Single-Gene Trait

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Trait controlled by a single gene that has two alleles

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Polygenic Trait

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Trait controlled by two or more genes

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Directional Selection

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Form of natural selection in which the curve moves.

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Directional Selection

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Occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve.

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Stabilizing Selection

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Form of natural selection by which the center of the curve remains in its current position.

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Stabilizing Selection

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Occurs when individuals near a distribution curve have higher fitness than individuals at the other end.

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Disruptive Selection

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Form of natural selection in which a single curve splits into two

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Disruptive Selection

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Occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals in the middle

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Genetic Drift

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Random change in allele frequencies that occurs in small populations

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Founder Effect

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Change in allele frequencies as a result of the migration of a small subgroup of a population

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Hardy-Weinberg Principle

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Principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change.

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Genetic Equilibrium

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Situation in which allele frequencies remain constant.

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Evolution

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Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms

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Theory

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Well tested explanation that unifies a broad range of observations.

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Hypothesis

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Possible explanation for a set of observations or possible answer to a scientific question.

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Fossil

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Preserved remains or evidence of ancient organisms.

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Geology

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The study of the earth, especially the earth's history as recorded in rock.

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Artificial Selection

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Selection by humans for breeding or useful traits from the natural variation among different organisms

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Struggle for existence

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Competition among members of a species for food living space, and the other necessities of life.

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Fitness

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Ability of an organism to survive and reproduce in its environment

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Adaptation

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Inherited characteristics that increase an organisms chances of survival.

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Survival of the Fittest

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Process by which individuals are better than suited to their environment survive and reproduce most successfully; also called natural selection

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Descent with modification

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Principle that each living species has descended with changes from other species over time

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Common descent

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Principle that all living things were derived fro common ancestors.

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Mutation

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Change in the DNA sequence that affects genetic information

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Homologous Structures

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Structures that have different mature forms in different organisms but develop from the same embryonic tissues.

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Vestigial

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Organ that serves no useful function in an organism.