[19.3-4] competition & predation

competition between members of the same species for (scarce) resources eg. food, light, space

competition between members of different species for (scarce) resources eg. food, space, light, mineral ions, water

• if species have a rapid reproduction rate, they can be good at competing for resources in the short term, especially if they have few competitors • if species are slower to reproduce, they may be better at competing in the long-term (succession)

an organism that feeds on another organism, known as their prey

when one organism is consumed by another

• predators eat prey, reducing prey’s population • fewer prey available so predators are in greater competition with each other for prey left • fewer predators as some cannot eat enough prey to survive or reproduce • fewer predators left so fewer prey eaten, more survive and are able to reproduce • prey population increases • more prey now available as food, so predator population inreases

• always more prey than predator (pyramids of biomass) • wild fluctuations in population over time • time-lag in population change for prey followed by population of predator > prey population has control of predator population, which essentially impacts their own • other factors influencing populations eg. disease, hunting, food source for prey