Ap Bio Chapter 21 Terms

evolve

change over time observed in natural populations and

fossil record.

Evolutionary theory

understanding the mechanisms of evolutionary change. helps in the study and treatment of diseases and how species interact

Charles Darwin

English naturalist. He studied the plants and animals of South America and the Pacific islands, and in his book On the Origin of Species by Means of Natural Selection (1859) set forth his theory of evolution.

Darwin's three postulates

species change over time, divergent species share a common ancestor, mechanism that produces changes in species is natural selection

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.

endemic species

A species that is found in its originating location and is generally restricted to that geographic area.

biological evolution

changes in the genetic makeup of populations over time.

Population

a group of individuals of a single species that live and interbreed in a particular geographic area at the same time.

Mutation

change in a DNA sequence that affects genetic information

artificial selection

selective breeding of plants and animals to promote the occurrence of desirable traits in offspring

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

Number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene (p and q)

genotype frequency

proportion of each genotype among individuals in the population (p2 + 2pq + q2)

Adaptation

a favored trait that evolves through natural selection.

gene flow

Movement of alleles into or out of a population due to the migration of individuals to or from the population

genetic drift

Changes in gene frequencies from generation to generation as a result of random (chance) processes.

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.

sexual selection

nonrandom mating in which an organism's phenotype influences its ability to attract mates

intersexual selection

also called mate choice, individuals of one sex are choosy in selecting their mates from the other sex

intrasexual selection

selection within the same sex, individuals of one sex compete directly for mates of the opposite sex

Hardy Weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time

stabilizing selection

Natural selection that favors intermediate variants by acting against extreme phenotypes

directional selection

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.

disruptive selection

favors individuals at both extremes of the phenotypic range over individuals with intermediate phenotypes

heterozygous advantage

Heterozygous alleles have greater selective advantage than either homozygous condition (defined in terms of genotype not phenotype)

relative fitness

the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

causes of microevolution

genetic drift, gene flow, mutations, nonrandom mating, natural selection

Hardy-Weinberg conditions

A large breeding population.

Random mating.

No change in allelic frequency due to mutation.

No immigration or emigration.

No natural selection.