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
