Population Density, Dispersion,
Demographics
Demographics
What does the Type II survivorship curve represent?
Species with a constant rate of death over an individual's lifespan
Define exponential population growth and describe the shape of its curve.
Definition: population growth under ideal conditions
Shape: growth curve is J-shaped
What does K mean in the logistic growth model?
Carrying capacity: the maximum population that a particular environment can sustain
Define iteroparity and give an example of a species.
Definition: repeated reproduction, involving an individual producing a small number (usually 1) of offspring multiple times throughout their life
Examples: humans, oak trees
Define demographic transition.
The move from high birth rate and high death rate to low birth rate and low death rate
Which processes contribute to the size of a population and how to changes over time?
Adding individuals (births, immigration) and removing individuals (deaths, emigration)
What is happening to the population when r = 0 (the per capita change in population size is 0)?
There is zero population growth, so birth rate = death rate
When does population growth begin to slow?
The population growth rate begins to decrease as N approaches K (occurs close to the middle of the S-curve)
What are the variables of life histories?
- the age at which reproduction begins
- how often the organism reproduces
- how many offspring are produced per reproductive episode
List the mechanisms for density-dependent regulation.
- competition for resources, territoriality, disease, intrinsic factors, and toxic waste
What is the difference between population density and population dispersion?
Population density is the number of individuals per unit of area or volume within a geographical boundary.
Population dispersion is the pattern in space regarding individuals within the geographical boundaries.
Which types of populations will exhibit exponential growth?
- Populations that are introduced to a new
environment
- Populations that are rebounding after experiencing a catastrophic event that caused reduction
When is the logistic growth model used?
- when predicting the rate of recovery for small populations
- when estimating sustainable harvest rates for wildlife
- when estimating the critical size below which populations become at risk for extinction
What is the difference between K-selection and r-selection?
K-selection is density-dependent and selects for life history traits that are sensitive to population density.
r-selection is density-independent and selects for life history traits that maximize reproduction.
What is ecological footprint? Is the U.S. high or low on the scale?
Ecological footprint is the aggregate land and water area needed to sustain the people of a nation (a measure of how close we are to Earth's carrying capacity). The U.S. has a high ecological footprint.