Unit 6 Ch. 15 & 16 Biology 1 Vocabulary

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Fossil

Back 1

Preserved remains or evidence of an ancient organism

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Adaptation

Back 2

Inherited characteristic that increases an organism’s chance of survival

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Evolution

Back 3

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

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Natural Selection

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Process by which individuals that are better suited to their environment survive and reproduce most successfully; Also called Survival of the fittest

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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 Organ (Structure)

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Organ that serves no useful function in an organism
Example: Appendix

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Speciation

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Formation of new species

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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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Genetic Equilibrium

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Situation in which allele frequencies remain constant

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Genetic Drift

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Random change in allele frequencies that occurs in small populations

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Directional Selection

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Form of natural selection in which the entire curve moves; 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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Disruptive Selection

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Form of natural selection in which a single curve splits into two; Occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

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Artificial Selection

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

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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; Occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end

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Paleontologist

Back 15

Scientist who studies fossils

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Reproductive Isolation

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Separation of species or populations so that they cannot interbreed and produce fertile offspring

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Geographic Isolation

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Form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

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Behavioral Isolation

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Form of reproductive isolation in which two populations have differences in the courtship rituals or other types of behavior that prevent them from interbreeding

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Temporal Isolation

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Form of reproductive isolation in which two populations reproduce at different times

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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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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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Niche

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Full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions