8.3: Demography Flashcards
What is demography?
The study of vital statistics of populations and how they change over time
What is a life table?
An age-specific summary of the survival pattern of a population
What is a life table represented by?
A survivorship curve
What are the three types of survivorship curves?
Type I, II, III
What is a type I curve?
- low death rate during early/middle life and high death rate later in life
What is a type 2 curve?
- constant death rate over the lifespan of the organism
What is a type III curve?
- high death rate early in life and lower death rate for those that survive early life
Which formula measures the per capital rate of increase in population size?
Dn/dt= B-D
What are the two models for population growth?
Exponential and logistic growth models
What is the exponential growth model? (2)
- a population living under ideal conditions (ie. easy access to food, abundant food, free to reproduce, etc.)
- population grows rapidly
Note: no limits, unlimited resources
In the exponential growth model, at what rate does the population grow? What type of curve does this represent on the graph?
- constant rate of growth
- j-shaped curve
What is the population growth rate formula for exponential growth model?
dn/dt= rmaxN
- rmax is the maximum per capita growth rate of the population
- N is the population size
What is the logistic growth model?
The per capita rate of increase approaches zero as the population size nears its carrying capacity
What is carry capacity?
- the maximum population size of a species that can be sustained by that environment (enough food, water, etc.)
What occurs to the resource availability in logistic growth?
- the density of individuals exceeds the system’s resource availability
What is the formula for population growth rate for logistic growth?
dn/dt= rmaxN[(k-N)/k)
- k is carrying capacity
- rmaxN is exp. Growth
What does (K-N) do when we get closer to carrying capacity?
Slows down the growth rate
Exponential growth implies that there are unlimited resources. How can we modify exponential growth to be more representative of a real situation with limits?
Logistic growth
