Biotic factorsSpec 4.7.1.3
Biotic (living) factors can also change a community. The four you need to know are:
| Biotic factor | How a change could affect a community |
|---|---|
| Availability of food | Less food means more competition, so animal numbers fall. More food means numbers can rise |
| New predators arriving | Prey are eaten, so the prey population falls. Anything the prey ate may then increase |
| New pathogens | Disease can kill or weaken many organisms of a species, so the population falls |
| One species outcompeting another | The weaker competitor gets less of the food, light or space it needs. Its numbers may become no longer sufficient to breed, so the species can die out in that area |
A change in one population affects others. If a new predator reduces the number of prey, the predator's other food sources and the prey's food source are all affected.