Living together doesn't mean helping each other
- The idea
- Predict
- See it
- Why
- Check
The idea
“If two species live together or share the same food, they must be helping each other.”
Species found together year after year look like a team. Using the same limited food or space is actually what makes them rivals.
The short version
The mistake: If two species live together or share the same food, they must be helping each other.
What's actually true: Species that share a limited resource compete, and each does worse with the other present than alone.
- Two species can live side by side for years and still compete. Interspecific competition happens when both use the same limited resource, like light or nutrients.
- To find what one species does to another, compare it alone with it together. Fewer together means harm. More together means help.
- In competition, each species does worse with the other present, though one may lose much more. In mutualism, both do better.
On the exam: Compare each species alone and together. If both do worse together, they are competitors.