chapter 21 ~ microevolution Flashcards
A group of organisms of the same kind that live together in the same place.
Population
Differences in appearance or function between individual organisms.
Phenotypic variation
Variation that is measured on a continuum (such as height in human beings) rather than in discrete units or categories.
Quantitative variation
Variation that exists in two or more discrete states, with intermediate forms often being absent.
Qualitative variation
The existence of discrete variants of a character among individuals in a population.
Polymorphism
The sum of all alleles at all gene loci in all individuals in a population.
Gene pool
The percentage of individuals in a population possessing a particular genotype.
Genotype frequencies
The abundance of one allele relative to others at the same gene locus in Individuals of a population.
Allele frequencies
A conceptual model that predicts what one would see if a particular factor had no effect.
Null models
An evolutionary rule of thumb that specifies the conditions under which a population of diploid organisms achieves genetic equilibrium.
Hardy-Weinberg principle
The point at which neither the allele frequencies nor the genotype frequencies in a population change in succeeding generations.
Genetic equilibrium
A spontaneous and heritable change in DNA.
Mutation
Random fluctuations in allele frequencies as a result of chance events; usually reduces genetic variation in a population.
Genetic drift
An evolutionary phenomenon in which a population that was established by just a few colonizing individuals has only a fraction of the genetic diversity seen in the population from which it was derived.
Founder effect
The number of surviving offspring that an individual produces compared with the number left by others in the population.
Relative fitness
A type of natural selection in which individuals near one end of the phenotypic spectrum have the highest relative fitness.
Directional selection
A type of natural selection in which individuals expressing intermediate phenotypes have the highest relative fitness.
Stabilizing selection
A type of natural selection in which extreme phenotypes have higher relative fitness than intermediate phenotypes.
Disruptive selection
A form of natural selection established by male competition for access to females and by the females choice of mates.
Sexual selection
Differences in the size or appearance of males and females.
Sexual dimorphism
A special form of non random mating in which genetically related individuals mate with each other.
Inbreeding
The maintenance of two or more phenotypes in fairly stable proportions over many generations.
Balanced polymorphism
An evolutionary circumstances in which individuals that are heterozygous at a particular locus have higher relative fitness than either homozygous.
Heterozygote advantage
A form of natural selection in which rare phenotypes have a selective advantage simply because they are rare.
Frequency-dependent selection
