STAGES OF POPULATION GROWTH Population Growth can be

STAGES OF POPULATION GROWTH

Population Growth can be… • Exponential (J curve) OR Limited (S curve)

STAGES OF POPULATION GROWTH 1) Lag Phase 3) Stationary Phase 2) Log Phase 4) Decline/Death Phase

POPULATION GROWTH STAGES • 1) LAG PHASE – Only a small number of organisms are sexually mature and able to reproduce – The organisms may be adjusting to their environment

POPULATION GROWTH STAGES • 2) LOG PHASE – Exponential or Logarithmic acceleration – Many organisms have reached sexual maturity – They are able to reproduce – The organisms have adjusted to the conditions around them (able to get food, shelter, water, etc for survival)

POPULATION GROWTH STAGES 3) STATIONARY PHASE – Growth ceases (slows down) and population remains relatively fixed in size – The carrying capacity is reached – The number of births and deaths balance each other out – The immigration and emigration rate are roughly the same

POPULATION GROWTH STAGES • 4) DECLINE/DEATH PHASE – Population dies off – May return to lag phase and the cycle may repeat

PREDATOR PREY CURVES

PREDATOR PREY CURVES

PREDATOR/ PREY CURVES • Show the rise and fall of predator and prey populations • Developed by Italian mathematician Volterra from watching the rise and fall of Adriatic fishing fleets. • Shows peaks and valleys when population levels rise and fall in response to the predator-prey feeding relationship

PREDATOR/ PREY CURVES • theory suggest that… • when prey are numerous their predators increase in numbers • This reduces the prey population, which in turn causes predator number to decline. • The prey population eventually recovers, starting a new cycle.

HARE = prey, LYNX = predator

YOUR TURN… Using the values on this graph, write 5 sentences to explain what is happening…

Credits • Mrs K Casha