- Birth Rate: the reproductive capacity of the population
- Emigration: The movement of individuals out of a population
- Immigration: the movement of individuals into a population
- Population: a group of organisms of a single species interbreeding and occupying a particular area
1. Lag Phase: Little multiplication or growth. Only few individuals therefore slow growth/breeding rate. Period of adaptation or preparation for growth. Lots of metabolic activity, ie, enzyme synthesis.
2. Exponential phase: Increasing numbers = increasing repro.
3. Stationary phase. Birth rate = Death rate. Population reaches carrying capacity (or maximum size able to be supported by habitat or area)
4. Death phase: Death rate higher than birth rate. For example in terms of microbiology, maybe all the food in a solution has been used up.
FACTORS CONTROLLING GROWTH
- Environmental resistance. Population growth slows down due to the followung
- available food
- accumulation of toxic waste
DENSITY DEPENDENT FACTORS (effect of factor increases depending on how dense a population is/the proximity)
- Accumlation of toxic waste
- Depeletion of food supply
DENSITY INDEPENDENT FACTORS (all plants/animals affected no matter size of pop)
- Other natural disasters
Populations fluctuate in numbers. This may be the consequence of weather patterns or temperature. Population oscillations are regulated by negative feedback.
Negative feedback: when there is a change in a monitored variable, a response is trigged to counteract the initial fluctuation/change
For example: occassional the greenfly population will explode in numbers. This could be a reduction in the numbers of their predators. However this will self regulate due to competition for resources between the greenflies.
There are two types of competition
Intraspecific Competition is competition between one species.
Interspecific Competition is competition between other species.
- Pests directly cause disease in crop organisms
- make infection by pathogens more likely
- Can spoil food during transport or storage