Summary
The formation of new species when populations diverge enough to become reproductively isolated.
In depth
Speciation requires gene flow to be reduced and divergence to build up until isolating barriers exist. It can take thousands to millions of years, although polyploidy in plants can create a species in one generation.
Both ecological (selection) and genetic (drift, incompatibilities) factors contribute.
Isolating barriers evolve as a side effect of divergence (as in the Dobzhansky-Muller model, where new alleles that work in each population fail together in hybrids). Reinforcement can strengthen prezygotic isolation if hybrids are unfit. Speciation can be studied in the lab: fruit flies reared on different foods have started to prefer mates from the same diet.
Modes are classified by geography: allopatric, peripatric (small isolated founder population), parapatric (adjacent ranges with a gradient) and sympatric. In practice most speciation probably involves some gene flow at some time. Rates vary: cichlid fish in Lake Victoria produced hundreds of species in about 15,000 years.
Key idea: speciation is a process, not an event, and species boundaries are often blurry while it takes place.
Frequently asked questions
What is Speciation?
The formation of new species when populations diverge enough to become reproductively isolated.
Which area of biology covers Speciation, and how advanced is it?
Speciation is one of the 53 topics in Evolution. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Allopatric Speciation, Sympatric Speciation, Disruptive Selection.
Can you give an example of Speciation?
Over 800 species of fruit flies in Hawaii arose from a single colonist.
What should I learn before Speciation?
Work through the Beginner topics in Evolution first, such as Evolution, Natural Selection, Charles Darwin, then return to Speciation. Intermediate topics assume the Beginner vocabulary.
What topics are related to Speciation?
The closest topics to Speciation are Allopatric Speciation, Sympatric Speciation, Disruptive Selection, Founder Effect and Bottleneck. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Speciation?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Speciation. To practise the whole of Evolution, use the Evolution quiz.
How is Speciation different from Allopatric Speciation?
Speciation: The formation of new species when populations diverge enough to become reproductively isolated. Allopatric Speciation: Speciation after a geographic barrier separates populations, as with Darwin's finches on separate islands. Read both side by side and note what each one explains.
How should I study Speciation step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Allopatric Speciation and explain the difference aloud. Finally, take the Evolution quiz and come back to this page for any question you miss.