An empty patch refills only if animals can reach it
- The idea
- Predict
- See it
- Why
- Check
The idea
“A big patch of good habitat will get its species back on its own, and being cut off only protects it.”
Size and isolation are easy to see on a map. Harder to see is that the animals have to get back in.
The short version
The mistake: A big patch of good habitat will get its species back on its own, and being cut off only protects it.
What's actually true: A patch gets a lost species back only when individuals arrive from a source population they can reach.
- A patch that loses its population gets it back by recolonization, when individuals arrive from somewhere else.
- That takes a source population within reach and a route in. A corridor, a strip of habitat linking patches, is one.
- Size still matters. A big patch is less likely to lose everyone. Once it's empty, though, size alone can't bring anyone back.
On the exam: An empty patch refills only if individuals can reach it. Find the source and the route.