Speciation — Science definition
The evolutionary process by which one ancestral species splits into two or more distinct species that can no longer interbreed.
Where it is taught
- Speciation & Mechanisms of Evolution — Evolution, Ancestry & Biodiversity, Life Science: Biology, Grade 10
In use
Under the biological species model, sufficiently isolated lineages may be classified as separate species — the process of speciation.
Speciation & Mechanisms of Evolution
Questions using speciation
Problem 1
Answer and explanation
Gene flow moves alleles between populations and keeps their gene pools mixed and similar, so they can't diverge into separate species. Reproductive isolation stops that exchange of genes, letting mutation, drift, and selection push each population's gene pool in its own direction until they become separate species.
Problem 2
Answer and explanation
Isolation stops gene flow, so alleles arising in one population are not shared with the other and differences can accumulate separately. Time is needed because the mechanisms that produce divergence act gradually: mutation introduces new alleles at a low rate, selection shifts frequencies over generations where environments differ, and drift alters them by chance. Reproductive barriers generally emerge as a by-product of accumulated differences rather than appearing at once, so neither isolation without time nor time without isolation is usually sufficient.
Response criteria
- State a biologically accurate conclusion.
- Show the data, mechanism, or calculation that supports it.
- Include units, conditions, or limits where relevant.
Problem 3
- causing mutations to occur
- preventing gene flow so the populations can diverge
- making populations identical
- increasing population size
Answer and explanation
preventing gene flow so the populations can diverge
Separation stops the exchange of alleles, so mutation, drift, and different selective pressures can accumulate differences independently in each population.