A gap that survives the same conditions is inherited
- The idea
- Predict
- See it
- Why
- Check
The idea
“Two populations differ because their surroundings changed each one as it grew.”
Bodies do respond to where they live, so it's tempting to blame each population's home. Give both the same home and see.
The short version
The mistake: Two populations differ because their surroundings changed each one as it grew.
What's actually true: If a difference stays when both populations grow up in the same conditions, it's inherited, often built by natural selection.
- Phenotypic plasticity means each body responds to its surroundings. A genetic difference means the populations carry different alleles. Both are common.
- To tell them apart, raise both in the same conditions, ideally for two generations. A plastic gap fades. An inherited one stays.
- Selection often builds inherited gaps. The low-plate allele was rare in the sea, but lake fish carrying it left more young, so it spread.
On the exam: If a difference survives shared conditions, it's inherited. Selection often built it.