BIO 103: Ch. 23 Genes Within Populations

Evolution

Any change in the inherited traits of a population that occurs from one generation to the next; i.e., over a time period longer than the lifetime of an individual in the population; (b) more simply defined, biological evolution is descent with modification

Microevolution

A change in allele frequencies in a population over time.

Speciation

The process by which one species splits into two or more species.

Macroevolution

The broad pattern of evolution over time; includes the origin of new groups of organisms through a series of speciation events.

Genetic Variation

Differences among individuals in the composition of their genes or other DNA sequences.

Population

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.

Allele

Any of the alternative forms of a gene that may occur at a given locus; these alternative forms may produce distinguishable phenotypic effects.

Gene Pool

The 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

Hardy-Weinberg Equilibrium

The state of a population in which frequencies of alleles and genotypes remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work

Mutation

A change in the nucleotide sequence of an organism's DNA (or in the DNA or RNA of a virus).

Genetic Drift

A 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.

Gene Flow

The transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes.

Natural Selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Sexual Selection

A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates.