AP Biology Evolution Study Guide

Sexual Selection

A type of differential reproduction that results from variable success in obtaining mates

Prezygotic Isolation Mechanisms

A type of reproductive isolation in which the formation of a zygote is prevented; these mechanisms may range from physical separation in different habitats to gametic in which gametes are incapable of fusing

Postzygotic Isolation Mechanisms

A type of reproductive isolation in which zygotes are produced but are unable to develop into reproducing adults (ranging from inviable zygotes or embryos to adults that are sterile)

Punctuated Equilibrium

A hypothesis about the mechanism of evolutionary change proposing that long periods of little or no change are punctuated by periods of rapid evolution

Species/Speciation

A kind of organism/when one species diverges enough genetically or geographically to create two separate species

Bottleneck Effect

A loss of genetic variability that occurs when a population is reduced drastically in size (usually due to a natural disaster)

Charles Darwin

A British biologist who popularized the theory of evolution through natural selection and descent with modification

Alfred Russel Wallace

A British naturalist who developed ideas similar to Darwin's on the topic of evolution

Jean Baptist de Lamarck

A biologist who believed in the inheritance of aquired characteristics

Stabilizing Selection

A form of selection in which selection acts to eliminate both extremes from a range of phenotypes

Disruptive Selection

A form of selection in which selection acts to eliminate rather than favor the intermediate type (a graph is split in the middle - favoring the extremes of a trait, sometimes leading to speciation)

Directional Selection

A form of selection in which selection acts to eliminate rather than favor the intermediate type (a graph moves either to the right or left - favoring one trait over the other)

Genotype Frequencies

A measure of the occurrence of a genotype in a population expressed as a proportion of the entire population (see allele/allelic frequency)

Allelic Frequency

A measure of the occurrence of an allele in a population, expressed as a proportion of the entire population (see genotype frequencies)

Adaptation

A peculiarity of structure, physiology, or behavior that promotes the likelihood of an organism's survival and reproduction in a particular environment

Radioactive Dating

A process for determining the age of an object by measuring an amount of given radioactive material it contains

Gene Pool

All the alleles present in a species

Selection Pressure

An agent of differential mortality or fertility that tends to make a population change genetically

Evolutionary Bottleneck

An event that drastically reduces the size of a population, possibly eliminating certain traits (see bottleneck effect)

Inheritance of acquired characteristics

Characteristics acquired during an organism's lifetime will be passed on to their children

Evidence for Evolution: Biochemical

Embryology, biochemistry, DNA, artificial selection

Evidence for Evolution: Geologic

Fossils/fossil record, paleontology, biogeography

Gametic Isolation

Gametes of one species function poorly with the gametes of another species or within the reproductive tract of another species

Evidence for Evolution: Developmental

Homologous and analogous structures, vestigial structures

Hybrid Inviability/Sterility

Hybrids may be vigorous, but they are sterile or produce inviable offspring

Developmental Isolation

Mating and fertilization are successful, but the embryo doesn't develop properly

Variation

Minute differences in individuals of the same species

Genetic Drift

Random fluctuation in allele frequencies over time by chance

Microevolution

Refers to the evolutionary process itself. Evolution within a species (see adaptation)

Behavioral Isolation

Species differ in their mating rituals

Geographic Isolation

Species do not occur in the same area; populations can be separated by natural barriers such as mountains or manmade ones like roads

Ecological Isolation

Species occur in the same area, but they occupy different habitats and rarely encounter each other

Temporal Isolation

Species reproduce in different seasons or at different times of the day

Mechanical Isolation

Structural differences between species prevent mating

Mutation Pressure

The change in allele frequencies due to the repeated occurrence of the same mutations (not as powerful as genetic drift in the grand scheme of evolution)

Survival of the Fittest

The concept that the organisms best suited to live in their environment will survive

Genetic Equilibrium

The condition of an allele or genotype in a gene pool in which the frequency does not change from generation to generation

Macroevolution

The creation of new species and the extinction of old ones

Natural Selection

The differential reproduction of genotypes; caused by factors in the environment; leads to evolutionary change

Allopatric Speciation

The differentiation of geographically isolated populations into distinct species

Sympatric Speciation

The differentiation of populations within a common geographic area into separate species

Founder Effect

The effect by which rare alleles and combinations of alleles may be enhanced in new populations

Phylogeny

The evolutionary history of an organism

Fitness

The genetic contribution of an individual to succeeding generations. Relative fitness refers to the fitness of an individual relative to other individuals in a population

Convergent Evolution

The independent development of similar structures in organisms that are not directly related; often found in organisms in similar environments (ex. birds and bats developing wings)

Polymorphism

The presence in a population of more than one allele of a gene at a frequency greater than that of newly arising adaptations

Heterozygote Advantage

The situation in which individuals heterzygous for a trait have a selective advantage of the those who are homozygous; an example is sickle cell anemia

Gene Flow

The transfer of alleles from one population to another

Gradualism

The view that species change very slowly in ways that may be imperceptible from one generation to the next but that accumulate and lead to major changes over thousands or millions of years (in contrast to Punctuated Equilibrium)

Charles Lyell

Wrote the book Principle of Geology that influenced Darwin's conclusion that living species had arose from ancestral species