(Week 4) How Does Life Evolve? - Evolutionary Processes BSC 101 ISU

Evolution

Descent with modification from a common ancestor

Fitness

Ability of an organism to survive and reproduce in its environment

Gene

A segment of DNA on a chromosome that codes for a specific trait

Allele

Different variations of a gene that leads to a different phenotype for that given trait

Mutation

A random error in gene replication. Can be beneficial, detrimental or have no effect

Antibiotics

Drugs that block the growth and reproduction of bacteria. Most commonly through interrupting protein synthesis

Genetic Variation

Differences in DNA sequences among individuals within a species. Can arise through mutations, genetic recombination and other processes

(Horizontal) Gene Transfer

The movement of genetic material between organisms other than by the transmission of DNA from parent to offspring

Natural Selection

The idea that

a) Individuals within a population vary

b) Some traits are heritable

c) More offspring are produced than can survive

d) Organisms best adapted to the environment have the best chance to survive and reproduce

Sexual Selection

A form of natural selection. Traits are 'selected' for because they increase an individual's chance of reproduction

Genetic Drift

A mechanism for evolution. A change in the allele frequency of a population as a result of chance events rather than natural selection. (Non-adaptive evolution)

Gene Flow

Transfer of genetic materials between

populations. Increases genetic diversity and can alter allele frequencies in the receiving population

Mutagen

A chemical or physical agent that interacts with DNA and makes mutations more likely to occur

Directional Selection

Form of natural selection in which the entire curve moves; occurs 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 the curve bulges in the middle; occurs when individuals in the middle of the distribution have higher fitness than individuals at either end of the curve

Diversifying Selection

Form of natural selection in which the curve bulges at both ends; occurs when individuals at both ends of a distribution curve have higher fitness than individuals in the middle of the curve

Speciation

The formation of new and distinct species in the course of evolution. Occurs when a portion of a parent species becomes unable to reproduce with the rest of the species

Allopatric Speciation

The formation of new species in populations that are geographically isolated from one another. Gene flow between the populations stops and genetic differences accumulate

Sympatric Speciation

The formation of new species in populations that live in the same geographic area. Often occurs through niche differentiation, reproductive isolation or chance mutations in offspring