Download Population Ecology - Madeira City Schools

Population Ecology
Chapter 36
I.
Population Structure and Dynamics
A. Population ecology is the study of how and why populations
change
1. Population – group of individuals of a single species that
occupy the same general area.
B. Population density – number of individuals of a species per unit
area or volume
1. Dispersion pattern – the way individuals are spaced within
their area
a. Clumped
b. Uniform
c. Random
C. Models can predict patterns of population growth
1. Exponential growth
a. the larger the population gets, the faster it grows
b. this growth cannot continue for a long time….why?
c. idealized picture of unregulated growth
d. G= rN (G = growth rate, N = population size, r = per
person (capita) rate of increase)
e. how do you get r? net increase
total population
2. Logistical Growth – idealized picture of population growth
that is slowed by limiting factors as the population increases
a. G = rN (K-N)
K
b. K = carrying capacity
Exponential Growth
Logistical Growth
C. Carrying Capacity = the number of organisms of a certain species
that an environment can support
1. “Limiting Factors” are things that keep a population from
growing (keep it at carrying capacity)
a. Density Dependent Limiting Factors = things that affect a
population only when the population is dense
examples: competition, predation, hunting, parasitism, crowding and stress
(rodents), disease.
b. Density Independent Limiting Factors = things that
affect a population no matter how dense the population is
examples: mostly abiotic factors, temperature, storms,
habitat disruption, natural disasters
floods, drought, any
D. Boom and bust cycles
E. Life history patterns
1. Life history – schedule of reproductions and death
a. age of first reproduction
b. frequency of reproduction
c. number of offspring
d. amount of parental care
2. Life histories have been shaped by natural selection
3. r-selection
a. r is maximized
b. usually small, short lived animals or plants
c. these species may experience unpredictable disturbances
4. K-selection
a. population size is near K
b. usually large, long-lived animals or plants
c. stable environments
II. Human Population Growth
A. Demography = study of population growth characteristics
B. Age of organisms affect population growth
a. pre-reproductive years
b. reproductive years
c. post-reproductive years
C. Immigration = movement of individuals into a population
D. Emigration = movement of individuals from a population
Why are these graphs shaped the way they are?