Ecology - the study of the interactions
between organisms and their environment.
Fields of ecological
research
Population
ecology - the study of all the individuals of a species within a given
area at a given time.
Density
and Dispersion (of populations)
Population
density - Image
Patterns of dispersion - Image and Fig. 38.1
clumped dispersion - Image
uniform dispersion - Image
random dispersion - Image
Population
Growth: Fig 38.2
Exponential growth
curve - Image
Reduction of r with
increase in N -
Image
Logistic growth
curve - Image and Fig 38.3
N = number of individuals in population
t = elapsed
time
b = average
birth rate/individual in the population
d = average
death rate/individual in the population
r = b-
d = the intrinsic rate of increase
rmax is when the population is experiencing minimum death rate and
maximum birth rate
K = carrying capacity
Examples of logistic
population growth. - Image
Density-independent
factors
Density-dependent
factors
Decreased birth rate at high population densities - Fig 38.4
and Image
Decreased survivorship at high population densities - Image
Maximizing yields Fig 38.5
r-selected (opportunistic) populations - characterized by
exponential growth and sudden crashes Fig 38.6
-- High intrinsic rate of growth (r)
-- Reproduce early, have many offspring
-- Offspring are small, mature rapidly, receive little parental care
-- Generations are relatively short, large brood size
-- Examples: dandelions, aphids, mice, cockroaches
K-selected (equilibrial) populations - Populations with
sigmoid growth curves limited by carrying capacity (K)
-- Include relatively slow-breeding organisms
-- Tend to live in stable, predictable habitats
-- Reproduce late, have small broods
-- Offspring are large, mature slowly
-- Receive intensive parental care
-- Generations are relatively long
-- Examples: oaks, humans, whales
Many organisms are intermediate
Demography - Statistical
Study of Populations
Survivorship Curves - Image and Fig 38.7
-- Type I
-- Type II
-- Type III
Life
history - the traits that an individual expresses during its life. (Types of metamorphosis)
Trade-offs
