Divergence into New Species
Understand divergence into new species: after geographic or reproductive isolation, populations accumulate different genetic changes over thousands of generations until they are no longer able to interbreed.
Key Concepts
Once isolated, the two groups face different environments. Group A might adapt to cold mountains (thick fur), while Group B adapts to hot valleys (thin skin).
Over thousands of generations, these differences stack up. Eventually, the genetic and physical differences become so great that even if the physical barrier were removed, the two groups could not produce healthy offspring together.
Common Questions
What causes populations to diverge into separate species?
After isolation, each population faces different environments and accumulates different random mutations. Natural selection favors different traits in each group until genetic differences are too great for interbreeding.
How long does speciation typically take?
Speciation usually takes thousands to millions of years, though in cases of strong selection pressure and short generation times, it can occur in hundreds of years. Sticklebacks isolated in separate lakes show rapid divergence.
How does divergence connect to common ancestry?
All species that diverged from a common ancestor share homologous structures from that ancestor. Divergence explains both the differences between species and their underlying similarities.