Biology Ch. 17

Chapter 17, Section 1; Genes and Variation (Gene Pool, Allele Frequency, Single-gene Trait, Polygenic Trait) Chapter 17, Section 2; Evolution as Genetic Change in Populations (Directional Selection, Stabilizing Selection, Disruptive Selection, Genetic Drift, Bottleneck Effect, Founder Effect, Genetic Equilibrium, Hardy-Weinberg Principle, Sexual Selection) Chapter 17, Section 3; The Process of Speciation (Species, Speciation, Reproductive Isolation, Behavioral Isolation, Geographic Isolation, Te…
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Terms in this set (...)

Gene Pool
All the genes, including all the different alleles for each gene, that are present in a population at any one time.
Allele Frequency
The number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene.
Single-gene Trait
Trait controlled by one gene that has two alleles.
Polygenic Trait
Trait controlled by two or more genes.
Directional Selection
Form of natural selection 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
Form of natural selection in which individuals near the center of a distribution curve have higher fitness than individuals at either end of the curve.
Distributive Selection
Natural Selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve.
Genetic Drift
Random change in allele frequency caused by a series of chance occurrences that cause an allele to become more or less common in a population.
Bottleneck Effect
A change in allele frequency following a dramatic reduction in size of a population.
Founder Effect
Change in allele frequencies as a result of the migration of a small subgroup of a population.
Genetic Equilibrium
Situation in which allele frequencies in a population remain the same.
Hardy-Weinberg Principle
Principle that states that allele frequencies in a population remain constant unless one or more factors cause those frequencies to change.
Sexual Selection
When individuals select mates based on heritable traits.
Species
A group of similar organisms that can breed and produce fertile offspring.
Speciation
Formation of new 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 develop differences in courtship rituals or other behaviors that prevent them from breeding.
Geographical Isolation
From of reproductive isolation in which two populations are separated by geographic barriers such as rivers, mountains, or bodies of water, leading to the formation of two separate subspecies.
Temporal Isolation
Form of reproductive isolation in which two or more species reproduces at different times.
Molecular Clock
Method used by researchers that uses mutation rates in DNA to estimate the length of time that two species have been evolving independently.