Populations Flashcards
Define abiotic factor
Non-living conditions in a habitat
Define biotic factor
Living components of an ecosystem
Define limiting factor
A component which prevents the rate of a process getting any greater
Define carrying capacity
The maximum population size that an environment can support
Give 3 examples of limiting factors for population size
- disease
- build up of toxic by-products
- availability of water/food
What is stage 1 of the standard growth curve called?
Lag phase
What happens in the lag phase?
- occurs due to acclimatisation
- low reproduction rate
- death rate lower than birth rate
What is stage 2 of the standard growth curve called?
Exponential phase
What happens in the exponential phase?
- rate depends on intrinsic rate of increase
- population grows rapidly
What is stage 3 of the standard growth curve called?
Stationary phase
What occurs in the stationary phase?
- death rate=birth rate
- carrying capacity reached
- slight increases and decreases occur
Define density independent factors
Factors that have an effect on the whole population regardless of its size
Give 3 examples of density independent factors
- Light intensity
- Temperature
- Climate
Define density dependent factors
Factors whose effects on the size or growth of the population vary with the population density
Give an example of a density dependent factor
Availability of food/water
Define intraspecific competition
Competition between organisms of the same species
Define interspecific competition
Competition between organisms of different species
What is the competitive exclusion principle?
Two species competing for the exact same resources cannot coexist, the one that uses the resources more effectively will ultimately eliminate the other
