Regulation of Population Growth
- negative feedback: as population size increases, either birth rates decline or mortality rates increase; e.g. when population reaches carrying capacity, mortality might increase due to more fights for limiting resources; resource limitation might decrease health ? lower birth rates; predators focus on most abundant prey;
- positive feedback: as population size increases, either birth rates increase or mortality rates decrease; e.g. decreased predation risk in dense fish swarms; finding a mate becomes easier;
Density-independent effects: climatic events (drought, flood, fire)
Prey-Predator oscillations: Increase inprey sustains increase in predator untilpredator decimates prey below sustainable population size; predator decrease, lower grazing pressure ? prey can increase again, ...