Unit 2: Biodiversity (Chapter 5)

Species Richness

Species Richness

The number of species in a given area.

Species evenness

The relative proportion of individuals within the different species in a given area.

Phylogeny

The branching pattern of evolutionary relationships.

Evolution

A change in the genetic composition of a population over time.

Microevolution

Evolution below the species level.

Macroevolution

Evolution that gives rise to new species, genera, families, classes, or phyla.

Gene

A physical location on the chromosomes within each cell of an organism.

Genotype

The complete set of genes in an individual.

Phenotype

A set of traits expressed by an individual.

Mutation

A random change in the genetic code produced by a mistake in the copying process.

Recombination

The genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division.

Artificial selection

The process in which humans determine which individuals breed, typically with a preconceived set of traits in mind.

Natural selection

The process in which the environment determines which individuals survive and reproduce.

Fitness

An individual’s ability to survive and reproduce.

Adaptation

A trait that improves an individual’s fitness.

Gene flow

The process by which individuals move from one population to another and thereby alter the genetic composition of both populations.

Genetic drift

A change in the genetic composition of a population over time as a result of random mating.

Bottleneck effect

A reduction in the genetic diversity of a population caused by a reduction in its size.

Extinction

The death of the last member of a species.

Founder effect

A change in the genetic composition of a population as a result of descending from a small number of colonizing individuals.

Geographic isolation

Physical separation of a group of individuals from others of the same species.

Allopatric speciation

The process of speciation that occurs with geographic isolation.

Reproductive isolation

The result of two populations within a species evolving separately to the point that they can no longer interbreed and produce viable offspring.

Sympatric speciation

The evolution of one species into two, without geographic isolation.

Genetically modified organism (GMO)

An organism produced by copying genes from a species with a desirable trait and inserting them into another species.

Range of tolerance

The limits to the abiotic conditions that a species can tolerate.

Fundamental niche

The suite of abiotic conditions under which a species can survive, grow, and reproduce.

Realized niche

The range of abiotic and biotic conditions under which a species actually lives.

Distribution

Areas of the world in which a species lives.

Niche generalist

A species that can live under a wide range of abiotic or biotic conditions.

Niche specialist

A species that is specialized to live in a specific habitat or to feed on a small group of species.

Mass extinction

A large extinction of species in a relatively short period of time.