[19.3-4] competition & predation

Question 1

what is intraspecific competition?

Answer 1

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

Question 2

what is interspecific competition?

Answer 2

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

Question 3

why do some species compete at different speeds?

Answer 3

• 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)

Question 4

what is a predator?

Answer 4

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

Question 5

what is predation?

Answer 5

when one organism is consumed by another

Question 6

describe the effect of predator-prey relationship on population size

Answer 6

• 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

Question 7

what are some key trends found in predator-prey relationships?

Answer 7

• 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