Population Growth Flashcards
shapes of population growth
in the presence of abundant resources, populations can grow at geometric or exponential rates
geometric growth
population growth without overlapping generations
- annual plants
- generations differ by a constant ratio
- discrete
exponential growth
growth in an unlimited environment that does not occur in discrete generations and is continuous
- bacteria
- helps establish populations in new environments, recover from exploitation or during exploitation of favourable conditions
assumptions of exponential growth
- no immigration or emigration (closed pop)
- constant births and deaths
- pop grows forever
logistic population growth
as resources are depleted, population growth rate slows and eventually stops
sigmoidal (S-shaped) population curve: population growth slows and ceases at carrying capacity (K).
rate of population growth decreases as (logistic)
density increases
density dependent factors
biotic factors such as disease that are influenced by population density
- food
- disease
- predation
density independent factors
abiotic factors such as floods that happen regardless of density
- rainfall
- floods
- temperature
