Gene flow
The movement of alleles between populations when individuals or gametes move. It makes populations more similar and adds new variation.
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Analogy
Seeds blown across a fence into a neighbour's garden.
In practice
Pollen carried by wind between two meadows brings alleles from one to the other.
Practice
Flashcards
- How does gene flow affect populations?It makes them more genetically similar and can add new alleles.
Interview questions
- List the conditions for Hardy-Weinberg equilibrium and explain why real populations rarely meet them.
- No mutation
- No selection
- No gene flow
- Large population, no drift
- Random mating
Questions people ask
How does gene flow affect speciation?
Gene flow keeps populations genetically similar, so it works against the splitting of one species into two. When a barrier stops gene flow, the populations can diverge through selection and drift. This is why isolation is a key step in forming new species.
Can gene flow happen between species?
Occasionally. When closely related species hybridise and the hybrids can reproduce, alleles move between them. This is called introgression. Modern humans, for example, carry a small percentage of Neanderthal DNA from interbreeding. It is much more common in plants than animals.