Population growth curves

what type of curve does a population curve

sigmodial curve

what are the three stages

1. exponential stage

2. transition stage

3. plateau/stationary stage

exponential phase

rate of population growth is rapid = no limiting factors restraining the growth

exponetial phase 2

natality rate is higher than mortality, abundant resources and limited environment resistance

transition phase

rate of growth begins to slow, limiting factors begin to affect and restrict population growth

transition phase 2

natality starts to fall and mortality starts to rise, some of the limiting factors are more scarce resulting in greater competition

plateau phase

eventually where the limiting factors restrict the population due to carrying capacity

plateau phase 2

natality rate and mortality rate become equal resulting in the population size being constant

what tends to cause exponential growth in populations

reproduction

what is the result of this

a positive feedback

what happens when any of the density dependent factors is absent

populations may grow exponentially

what may be the reasons DD factors are absent

• no competition for resources/not scarce

• lack/no apex predator

• density of the population is too small for disease/predation to affect