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Ch23 Campbell Biology, 9th ed Flashcards

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787916140The percentage, on average, of a population's loci that are heterozygous in members of the population.Average Heterozygosity
787916141Natural selection that maintains two or more phenotypic forms in a population.Balancing Selection
787916142Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population.Bottleneck Effect
787916143A graded change in a character along a geographic axis.Cline
787916144Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.Directional Selection
787916145Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes.Disruptive Selection
787916146Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.Founder Effect
787916147The transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes.Gene Flow
787916148The aggregate of all copies of every type of allele at all loci in every individual in a population. The term is also used in a more restricted sense as the aggregate of alleles for just one or a few loci in a population.Gene Pool
787916149A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. Effects of genetic drift are most pronounced in small populations.Genetic Drift
787916150Differences among individuals in the composition of their genes or other DNA segments.Genetic Variation
787916151Differences between the gene pools of geographically separate populations or population subgroups.Geographic Isolation
787916152The 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.Hardy-Weinberg Principle
787916153Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in a gene pool.Heterozygote Advantage
787916154Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice.Intersexual Selection
787916155Selection in which there is direct competition among individuals of one sex for mates of the opposite sex.Intrasexual Selection
787916156Evolutionary change below the species level; change in the allele frequencies in a population over generations.Microevolution
787916157Genetic variation that does not provide a selective advantage or disadvantage.Neutral Variation
787916158A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.Population
787916159The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population.Relative Fitness
787916160Differences between the secondary sex characteristics of males and females.Sexual Dimorphism
787916161A form of selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.Sexual Selection
787916162Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes.Stabilizing Selection
787916163Any of the alternative versions of a gene that produce distinguishable phenotypic effects.Allele
787916164A decline in the reproductive success of individuals that have a phenotype that has become too common in a population.Frequency-Dependent Selection
787916165The condition describing a nonevolving population.Hardy-Weinberg Equilibrium
787916166A change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity. Mutations also can occur in the DNA or RNA of a virus.Mutation
787916167A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are organisms with other characteristics.Natural Selection
787916168A change in a gene at a single nucleotide pair.Point Mutation
787916169A diagram used in the study of inheritance to show the predicted results of random fertilization in genetic crosses.Punnett Square
787916170A heritable feature that varies continuously over a range rather than in an either-or fashion.Quantitative Character
787916171An allele whose phenotypic effect is not observed in a heterozygote.Recessive Allele
787916172A human genetic disease caused by a recessive allele that results in the substitution of a single amino acid in a globin polypeptide that is part of the hemoglobin protein; characterized by deformed red blood cells (due to protein aggregation) that canSickle-Cell Disease

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