AP Natural Selection

Evolution

The change in a species over time

Lamarck

French naturalist who proposed that evolution resulted from the inheritance of acquired characteristics (1744-1829)

Darwin

English natural scientist who formulated a theory of evolution by natural selection (1809-1882)

Sedimentary strata

distinct layers of sediment that can reveal the age fossils

Fossils

Preserved remains of once-living organisms

Paleontology

a science dealing with prehistoric life through the study of fossils

Adaptation

inherited characteristic of organisms that enhance their survival and reproduction in specific environments.

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.

descent with modification

process by which descendants of ancestral organisms spread into various habitats and accumulate adaptations to diverse ways of life

artificial selection

Breeding organisms with specific traits in order to produce offspring with identical traits.

Variation

Any difference between individuals of the same species.

Overproduction of offspring

Organisms produce more offspring than needed to sustain the population.

Origin of Species

1859: Charles Darwin's book explained how various species evolve over time and only those with advantages can survive and reproduce

Drug resistant bacteria

strains of a bacterium that have adapted and are no longer controlled or killed by normal antibiotic treatment

MRSA

methicillin-resistant staphylococcus aureus

Microevolution

Change in allele frequencies in a population over generations.

genetic variation

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

Mutation

A change in a gene or chromosome.

nonheritable variation

variation due entirely to environmental factors

neutral variation

differences in DNA sequence that do not confer a selective advantage or disadvantage

point mutation

gene mutation in which a single base pair in DNA has been changed

gene duplication

The generation of extra copies of a gene in a genome over evolutionary time. A mechanism by which genomes can acquire new functions.

Sexual Reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

gene pool

Combined genetic information of all the members of a particular population

Hardy-Weinberg equilibrium

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

Population

A group of individuals that belong to the same species and live in the same area

Conditions of Hardy-Weinberg Equilibrium

1. No mutations

2. Random mating

3. No natural selection

4. Extremely large population size

5. No gene flow

adaptive evolution

evolution that results in a better match between organisms and their environment

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

founder effect

change in allele frequencies as a result of the migration of a small subgroup of a population

bottleneck effect

A change in allele frequency following a dramatic reduction in the size of a population

gene flow

movement of alleles from one population to another

relative fitness

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

directional selection

occurs when natural selection favors one of the extreme variations of a trait

disruptive selection

favors individuals at both extremes of the phenotypic range

stabilizing selection

favors intermediate variants by acting against extreme phenotypes

sexual selection

when individuals select mates based on heritable traits

intrasexual selection

A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex.

intersexual selection

individuals of one sex are choosy in selecting their mates from the other sex

sexual dimorphism

Differences in physical characteristics between males and females of the same species.

balancing selection

natural selection that maintains two or more phenotypic forms in a population

frequency-dependent selection

the fitness of a phenotype depends on how common it is in the population

heterozygote advantage

Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools.

Fitness

Ability of an organism to survive and reproduce in its environment

differential reproduction

Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits.

Coevolution

Process by which two species evolve in response to changes in each other

Fixed alleles

•all members of a population are homozygous for same allele

Population

A group of individuals that belong to the same species and live in the same area

heritable

Traits that can be passed on to offspring

population genetics

Study of allele frequency distribution and change under the influence of evolutionary processes.

neutral allele

An allele that does not affect fitness and therefore is not affected by natural selection.