Speciation

Adaptive Radiation

When a large number of species diverge from a common ancestor

Divergent Evolution

The process by which a species evolves into two or more descendants species.

Allopatric Speciation

Speciation occurs in different geographic areas.

Sympatric Speciation

Speciation occurs in the same geographic area.

Speciation

The formation of a new species that are able to interbreed and produce fertile offspring.

Species

A group of individuals that can interbreed and produce fertile offspring.

Selection Pressure

The environment factors that favour certain phenotypes.

Gradualism

Evolutionary change that occurs at a slow steady pace.

Punctuated Equilibrium

Short periods of rapid evolutionary change.

Ring Species

Two distinct species that are connected by a series of geographical subspecies where inbreeding can occur.

Cline

A gradual variation in the characteristics of a species or population in it's geographical separation.

Deme

A local population that has limited geneflow with larger populations.

Stabilising Selection

Selection for individuals with average phenotypes and against those with extreme phenotypes.

Directional Selection

Selection for one end of phenotypic range at expense of another.

Temporal

When the geneflow is prevented due to different mating times or day

Structural

Sex organs that prevent mating with other species.

Behavioural

Mating calls

Covergent Evolution

Species with similar niches that evolve similar adaptations. E.g fish have streamlined bodies.

Parallel Evolution

Unrelated ancestors that evolve in the same way.

Sequential Evolution

Species that has separated over time

Co-evolution

Unrelated ancestors that have a close relationship. Each species has an evolutionary effect on the other.

Genetic Drift

Random change in allele frequencies in a population that is determined by chance.

Founder Effect

When a small population becomes isolated from the main population.

Bottleneck Effect

When a population is reduced in size due to an environmental event causing the genetic diversity to decrease.

Endemic

Only found naturally in a certain country or area.

Hybrid

An individual formed by mating between genetically different populations or species.

Polyploidy

An organism with two or more sets of chromosomes.

Autopolyploidy

When polyploidy occurs within the same species due to non-disjunction.

Allopolyploidy

When polyploidy occurs from the mating of two closely related species that produce a hybrid.

Disruptive Selection

Selection against average phenotypes and for extremes.