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31 Cards in this Set
- Front
- Back
average heterozygosity
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the percent, on average, of a population's loci that are heterozygous in members of the population
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Balanced polymorphism
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when natural selection maintains stable frequencies of two or more phenotypes in a population
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balancing selection
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natural selection that maintains two or more phenotypic forms in a population
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bottleneck effect
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genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions
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cline
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a graded change in a character along a geographic axis
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directional selection
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natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals
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disruptive selection
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natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with the intermediate phenotypes.
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duplication
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an aberration in chromosome structure due to fusion with a fragment form a homologous chromosome, such that a portion of a chromosome is duplicated
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fitness
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the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
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founder effect
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genetic drift that occurs when a few individuals become isolated from a large population and form a new population whose gene pool composition is not reflective of that of the original population
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frequency-dependent selection
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a decline in the reproductive success of individuals that have a phenotype that has become too common in a population
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gene flow
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the transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes
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gene pool
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the aggregate of all of the alleles for all of the loci in all individuals in a population
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genetic drift
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a process in which change events cause unpredictable fluctuations in alleles frequencie form one generation to the next
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geographic variation
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differences between the gene pools of geographically separate populations of population subgroups
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Hardy-Weinberg equilibrium
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the condition describing a nonevolving population (one that is in genetic equilibrium)
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Hardy-Weinberg theorem
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the principle that frequencies of alleles and genotypes in a population remain constant from generation to generation provided that only Mendelian segregation and recombination of alleles are at work.
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Heterozygote advantage
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greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in a gene pool.
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Intersexual selection
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selection whereby individuals of one sex are choosy in selecting their mates from individuals of the other sex
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intrasexual selection
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a direct competition among individuals of one sex ually the males in vertebrates for mates of the opposite sex
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microevolution
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evolutionary change below the species level; change in he allele frequencies in a population over generations
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modern synthesis
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a union of ideas from several biological specialties which provides a widely accepted account of evolution
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mutation
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a change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity
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Neutral Variation
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genetic variation that does not appear to provide a selective advantage or disadvantage
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Phenotypic Polymorphism
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selection based solely on an individual's phenotype
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Population
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a localized group of individuals of the same species that can interbreed, producing fertile offspring
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Population genetics
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the branch of life sciences that studies short- and long-term changes in the size and age composition of populations, and the biological and environmental processes influencing those changes.
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Pseudogene
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a DNA segment very similar to a real gene but which does not yield a functional product
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Relative fitness
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the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population
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sexual dimorphism
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marked differences between the secondary sex characteristics of males and females
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sexual selection
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a form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates
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