Speciation - AP Biology

Species are the smallest group of individuals sharing a common ancestor. Uses evolutionary relationships to define species boundaries.

Geographic isolation. Physical separation initiates independent evolutionary paths.

The formation of new and distinct species in the course of evolution. The evolutionary process creating reproductively isolated lineages.

Any factor that prevents interbreeding between different species. Maintains species integrity by preventing hybridization.

When physical differences prevent successful mating. Structural incompatibility prevents successful copulation.

Accumulation of differences between groups leading to speciation. Genetic and phenotypic differences accumulate over time.

The condition of having more than two complete sets of chromosomes. Common mechanism of instant speciation in plants.

Polyploidy from duplication of chromosomes within a single species. Chromosome doubling within one species creates polyploids.

Species are the smallest group of individuals sharing a common ancestor. Uses evolutionary relationships to define species boundaries.

Geographic isolation. Physical separation initiates independent evolutionary paths.

Speciation driven by adaptation to different ecological niches. Natural selection drives adaptation to different environments.

Strengthening of reproductive barriers to reduce hybrid formation. Selection against hybrids increases reproductive isolation.

A connected series of neighboring populations that can interbreed, but the end populations cannot. Demonstrates how geographic variation can lead to speciation.

Species are groups of interbreeding natural populations that are reproductively isolated. Defines species by reproductive compatibility and gene flow.

Species are defined by structural features. Based on physical characteristics and anatomy.

The initial stage of species formation where populations are diverging. Early stages before complete reproductive isolation develops.

Gene flow can counteract speciation by homogenizing populations. Genetic exchange prevents population divergence and speciation.

Polyploidy resulting from two different species interbreeding. Hybrid polyploids from different parent species.

A mechanism that prevents fertilization from occurring. Acts before zygote formation to prevent mating or fertilization.

The diversification of a group of organisms into forms filling different niches. Rapid evolution into multiple specialized forms.

When sperm cannot fertilize the eggs of another species. Biochemical incompatibility prevents sperm-egg fusion.

A mechanism that reduces the viability or reproductive capacity of hybrids. Acts after fertilization to reduce hybrid fitness.

When two species live in the same area but different habitats. Microhabitat differences reduce encounter rates.

Hybrids are viable and fertile but their offspring are inviable or sterile. Second-generation hybrids show reduced fitness.

Temporal isolation. Prevents mating due to different breeding seasons or times.

Polyploidy. Chromosome multiplication creates instant reproductive isolation.

A geographic region where members of different species meet and mate. Contact zone where incomplete reproductive isolation exists.

Hybrids fail to develop or reach maturity. Genetic incompatibilities cause developmental failures.

Reinforcement. Selection against hybrids strengthens reproductive barriers.