Where a species lives isn't all it could use
- The idea
- Predict
- See it
- Why
- Check
The idea
“The places a species lives are the only places it can survive.”
You only see a species where it lives, so that range looks like its limit. Often a competitor draws the line.
The short version
The mistake: The places a species lives are the only places it can survive.
What's actually true: The fundamental niche is everything a species could use. The realized niche is the part it uses once competitors are present.
- A fundamental niche is every condition and resource a species could use on its own. Its tolerances set it.
- The realized niche is the part it actually uses. Competitors, predators and disease can shrink it.
- Removing a competitor moves the realized niche toward the fundamental one. The fundamental niche stays the same size.
On the exam: Where it lives with rivals is the realized niche. Where it could live alone is the fundamental niche.