Population Regulation Flashcards
Density Dependent
Have greater affect when the population is denser and less affect when the population is less dense.
- Competition for resource (water and food)
- Shelter (to hide/reproduce)
- Predation- population is large and dense therefore more interaction and contact and high level predators
- Disease- more interaction and contact. Organisms that live in close proximity (diseases spread quicker).
Density Independent
May affect all individuals in a population equally but some members of the population may be better able to adjust to them.
Physical Factors- rainfall, temperature, humidity, acidity and salinity
Catastrophic Events- flood, fire ,drought, volcanic eruption, tsunami, earthquake
Environmental limiting factors
Any factor that limits the growth of a population (inhibits population growth).
Biotic potential
Number of offspring capable of being produced by individuals of a species.
Carrying capacity
The total population able to be supported by a particular environment.
Negative Feedback
A change which reverses a particular trend. Sets in motion reverse processes.
Rate of increase or decrease of a population
r=(b+i)-(d+e) b= births i= immigrants e= emigrants d= deaths
Density dependent/independent
They influence the individuals ability to reproduce. (Natality/ birthrate is affected).
Can cause ill health or death. (Increases mortality/ death rate).
Population growth
The difference immigration and emigration.
A population in equilibrium B, D, E, I balance out and there is not net change in the population abundance. When losses exceed gains, the population declines.
Population equilibrium
A declining population
An increasing population
Rate of population change
Population equilibrium B+I=D+E A declining population D+E> B+I An increasing population B+I > D+E Rate of population change= B rate- D rate + net migration rate (positive or negative)
What is a population?
A population consists of all organisms of a given species that live in a particular area.
What are two important measures of a population?
Population size- the number of individuals
Population Density- the number of individuals per unit area or volume.
Density Equation
(total number of species)/(sample area)
Abundance Equation
total area x density