24.1 Populations And Sustainability Flashcards
1
Q
What happens in phase 1 of population growth? (Slow growth?
A
- the small number of individuals initially present reproduce increasing the total population
- birth rate > death rate, so population increaes in size
2
Q
What happens in phase two of population growth? (Rapid growth)
A
- number breeding individuals increases, so total population multiples exponentially
- there are no constraints that act to limit the population explosion
3
Q
What happens in phase three of population growth? (Stable state)
A
- further population growth is prevented by external constraints
- population size fluctuates but overall its size remains real stable
- birth rate ~ death rate
- fluctuations occur because of fluctuations in limiting factors e.g. disease or predators
4
Q
What is the carrying capacity?
A
The maximum population size that an environment can support
5
Q
What is immigration?
A
The movement of individual organisms into a particular area
6
Q
What effect does immigration have on population size?
A
It increases population size
7
Q
What is emigration?
A
The movement of individual organisms away from a particular area
8
Q
What effect does emigration have on population size?
A
It decreases population size
9
Q
What are density dependent factors?
A
Factors that have an effect on the whole population, regardless of its size
