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4.2.5: Key Terms

  • Page ID
    97105
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    adaptive evolution
    increase in frequency of beneficial alleles and decrease in deleterious alleles due to selection
    allele frequency
    (also, gene frequency) rate at which a specific allele appears within a population
    assortative mating
    when individuals tend to mate with those who are phenotypically similar to themselves
    bottleneck effect
    magnification of genetic drift as a result of natural events or catastrophes
    cline
    gradual geographic variation across an ecological gradient
    directional selection
    selection that favors phenotypes at one end of the spectrum of existing variation
    diversifying selection
    selection that favors two or more distinct phenotypes
    evolutionary fitness
    (also, Darwinian fitness) individual’s ability to survive and reproduce
    founder effect
    event that initiates an allele frequency change in part of the population, which is not typical of the original population
    frequency-dependent selection
    selection that favors phenotypes that are either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection)
    gene flow
    flow of alleles in and out of a population due to the individual or gamete migration
    gene pool
    all the alleles that the individuals in the population carry
    genetic drift
    effect of chance on a population’s gene pool
    genetic structure
    distribution of the different possible genotypes in a population
    genetic variance
    diversity of alleles and genotypes in a population
    geographical variation
    differences in the phenotypic variation between populations that are separated geographically
    good genes hypothesis
    theory of sexual selection that argues individuals develop impressive ornaments to show off their efficient metabolism or ability to fight disease
    handicap principle
    theory of sexual selection that argues only the fittest individuals can afford costly traits
    heritability
    fraction of population variation that can be attributed to its genetic variance
    honest signal
    trait that gives a truthful impression of an individual’s fitness
    inbreeding
    mating of closely related individuals
    inbreeding depression
    increase in abnormalities and disease in inbreeding populations
    macroevolution
    broader scale evolutionary changes that scientists see over paleontological time
    microevolution
    changes in a population’s genetic structure
    modern synthesis
    overarching evolutionary paradigm that took shape by the 1940s and scientists generally accept today
    nonrandom mating
    changes in a population’s gene pool due to mate choice or other forces that cause individuals to mate with certain phenotypes more than others
    population genetics
    study of how selective forces change the allele frequencies in a population over time
    population variation
    distribution of phenotypes in a population
    relative fitness
    individual’s ability to survive and reproduce relative to the rest of the population
    selective pressure
    environmental factor that causes one phenotype to be better than another
    sexual dimorphism
    phenotypic difference between a population's males and females
    stabilizing selection
    selection that favors average phenotypes

    4.2.5: Key Terms is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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