16 terms

Chapter 17 Evolution of Populations

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gene pool
All of the alleles in all the individuals that make up a population
allele frequency
How often a form of a gene appears in a gene pool.
polygenic trait
Traits controlled by two or more genes
directional selection
Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve
stabilizing selection
Natural selection that favors intermediate variants by acting against extreme phenotypes
disruptive selection
Form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle.
genetic drift
A change in the allele frequency of a population as a result of chance events rather than natural selection.
bottleneck effect
Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.
founder effect
Genetic 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.
genetic equilibrium
Condition in which the frequency of alleles in a population remains the same over generations.
species
A group of similar organisms that can breed and produce fertile offspring.
speciation
Formation of new species; an evolutionary process in which one species splits into two or more species.
reproductive isolation
Separation of a species or population so that they no longer interbreed and evolve into two separate species
behavioral isolation
Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding
geographic isolation
form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water
temporal isolation
Form of reproductive isolation in which two or more species reproduces at different times