C15

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Artificial Selection

Back 1

Darwin's term for the selective breeding of organisms selected for certain traits in order to produce offspring having those traits

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Natural Selection

Back 2

theory of evolution developed by Darwin, based on four ideas: excess reproduction, variations, inheritance, and the advantages of specific traits in an environment

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Evolution

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hereditary changes in groups of living organisms over time

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Derived Traits

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new feature that had not appeared in commonancestors

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Ancestral Traits

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more-primitive characteristic that appeared in common ancestors

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Homologous Structures

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anatomically similar structure inherited from a common ancestor

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Vestigial Structures

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reduced form of a functional structure that indicates shared ancestry

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Analogous Structures

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structure that has the same function but different construction and was not inherited from a common ancestor

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Embryo

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organism's early prebirth stage of development

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Biogeography

Back 10

study of the distrubution of plants and animals on earth

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Fitness

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measure of a trait's relative contribution to the following generation

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Camouflage

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morphological adaptations that allow organisms to blend their surroundings

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Mimicry

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morphological adaptation in which one species evolves to resemble another species from protection or other advantages

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Hardy-Weinberg Principle

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states that allelic frequencies in populations stay the same unless they are affected by a factor that causes change

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Genetic Drift

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random change in allelic frequencies in a population

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Founder Effect

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random effect that can occur when a small population settles in an area separated from the rest of the population and interbreeds, producing unique allelic variations

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Bottleneck

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process in which a large population declines in number, then rebounds

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Stabilizing Selection

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most common form of natural selection in which organisms with extreme expressions of a trait are removed

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Directional Selection

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shift of a population toward an extreme version of beneficial trait

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Disruptive Selection

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process in which individuals with alerage traits are removed, creating two populations with extreme traits

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Sexual Selection

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change in the frequency of a trait based on the competition for a mate

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Prezygotic Isolating Mechanisms

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occuring before breeding; produces fertilized egg, or zygote

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Postzygotic Isolating Mechanisms

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occuring after formation of a zygote

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Allopatric Specialization

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occures when a population divided by a geographic barrier evolves into two or more populations unable to interbreed

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Sympatric Specialization

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occurs when a species evolves into a newer species in an area without a geographic barrier

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Adaptive Radiation

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diversificaition of a species into a number of different species, often over a relatively short time span

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Gradualism

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theory that evolution occurs in small, gradual steps overtime

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Punctuated Equilibrium

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theory that evolution occurs with relatively sudden periods of speciation followed by long periods of stability