Sharing a habitat doesn't make species relatives
- The idea
- Predict
- See it
- Why
- Check
The idea
“Species that share a kind of habitat are probably close relatives, and ones that don't probably aren't.”
Ocean animals often look alike, so grouping them by home seems natural. Life in water can shape distantly related animals into the same streamlined form.
The short version
The mistake: Species that share a kind of habitat are probably close relatives, and ones that don't probably aren't.
What's actually true: Relatedness shows in homologous traits and DNA inherited from a common ancestor, not in where a species lives.
- Similar environments favor similar traits. When distantly related lineages evolve the same solution, like a streamlined body, that's convergent evolution.
- Homologous traits come from a common ancestor. A dolphin's flipper is built on the same set of bones as your arm.
- Habitat misleads the other way too. Once lineages split, each adapts to where it lives, so close relatives can live in very different places.
On the exam: Ignore where they live. Look for homologous traits and matching DNA.