Population dynamics Flashcards
What are the 4 factors that control population
- Birth rate
- Death rate
- Immigration
- Emigration
What is the equation to determine current population size
Past population + birth rate +immigration - emigration - death rate = current population
How would a population increase
Population will increase if the reproduction (birth) rate is high and the death rate is low
How would a population decline
Population will decline if the reproduction (birth) rate is low and the death rate is high
What are 4 factors that control birth rates
- Age of population (reached sexual maturity)
-Ratio of males : females - Breeding cycles + timing (seasons)
- How many times/ how often an individual can produce offspring
What are 4 factors that control death rates
- Food availability
- Drought (water availability)
- Predation
- Disease
What is an expression that describes a population stable in size
B + I = D + E
What is an expression that describes a population that is declining in size
B + I < D + E
What is an expression that describes a population that is increasing in size
B + I > D + E
What does “B” mean relating to population size
Birth rate
What does “I” mean relating to population size
Immigration
What does “D” mean relating to population size
Death rate
What does “E” mean relating to population size
Emigration
What is an expression that describes change in population size
B + I ≠ D + E
How do you work out death rate
Number of deaths / number of organisms within the population
How do you work out birth rate
Number of births / Number of organisms within the population
Define carrying capacity
Number of individuals that an
ecosystem/area can support
sustainably without damaging or over-exploiting the environment
Define density independent factors
factors where the density of the population has no effect on the chances of survival, eg flood, volcanic eruptions
Define density dependent factors
factors where the chances of survival are dependent on the density of the populations, eg disease, food supply
What is death rate
The number of deaths per 1000 population per year
What is birth rate
The number of offspring per 1000 population per year
What is emigration
Reduction in the population of the individuals leaving to another area
What is immigration
Addition of new individuals to the population from another area
What are 4 examples of density dependent factors
- Disease
- Competition (for..)
- Food supply
- Predation