Chapter 14
POPULATION ECOLOGY
POPULATION ECOLOGY

What is a population?



A group of individuals of
the same species that live
in a given area
Area is defined. Ex. Voter
population could be just
Spearfish or United States
Population Ecology

Changes in a population
and the biotic and abiotic
factors that influence
those changes
Organism
Population
Community
Ecosystem
POPULATION DISPERSION PATTERNS

Population density




# ind of a population/ unit
area or volume
Clumped dispersion
Uniform dispersion
Random dispersion
WHAT DISPERSION PATTERN WOULD YOU
PREDICT FOR A TERRITORIAL CHIPMUNK
SPECIES?
a)
b)
c)
Clumped
Uniform
Random
•Maximized rate with perfect
conditions
•Growth rate (G) = rN = average
rate of increase per individual
in the population X pop size
•Population size increases
exponentially
•Population can outstrip its
resources and crash
EXPONENTIAL GROWTH
Resource availability
limits population
growth.
Population growth
following the logistic
model stabilizes
around the carrying
capacity (K) of the
environment.
G = rN(K-N)/K
(K-N)/K = the closer N
comes to the carrying
capacity, the slower
the rate of growth
LOGISTIC GROWTH
WHICH OF THE FOLLOWING IS AN EXAMPLE OF
A POPULATION?
A) all of the microorganisms on your skin
 B) all of the species of cichlid fish in Lake
Victoria
 C) all of the students in your classroom
 D) all students attending colleges and
universities in your state
 E) the various plants found in prairies in the
western United States

THE DECLINE OF THE NILE PERCH IN LAKE
VICTORIA IN EAST AFRICA AND THE
REEMERGENCE OF CICHLIDS IS AN EXCELLENT
SITUATION FOR STUDY BY
A) geologists.
 B) ecologists.
 C) population ecologists.
 D) geographers.
 E) population geneticists.

SUSTAINABLE RESOURCE MANAGEMENT

Harvesting crops and hunted species without
damaging the resource.

Maintain healthy populations at population sizes that
can replace the harvested individuals
 Half
the carrying capacity is ideal
 Very difficult to do, because it is hard to determine K and N

Using water at a rate that allows for recharging
and keeping it clean
 Again
this is very difficult to figure out
Finding renewable energy sources
 Integrated pest management
 Recycle and reused materials

FOOTPRINT
ECOLOGICAL FOOTPRINT – GHA – GLOBAL
HECTARE
Cockroach population
- influenced by short generation time
- high reproductive rate (females lay lots of eggs)
Sustainability research helps give insight into how to control populations.
- mature female individuals contribute most to population growth
- target females for biggest impact
LIFE TABLES AND SURVIVORSHIP
Types of survivorship curves:
I = most individuals live to old age
II = equal probability of dying
through out life span
III = rapid die off of young, few
individuals live to old age
AGE STRUCTURE CAN HAVE AN IMPACT
CONSIDER A STABLE FROG POPULATION LIVING AT
CARRYING CAPACITY IN A POND. IF AN AVERAGE
FEMALE PRODUCES 6,000 EGGS DURING HER
LIFETIME AND AN AVERAGE OF 300 TADPOLES HATCH
FROM THESE EGGS, HOW MANY OF THESE TADPOLES
WILL, ON AVERAGE, SURVIVE TO REPRODUCE?
A) 0
 B) 2
 C) 10 to 20
 D) 100
 E) more than 100

IF A POPULATION HAS A BIRTH RATE OF 40
INDIVIDUALS PER 1,000 PER YEAR AND A DEATH RATE
OF 30 INDIVIDUALS PER 1,000 PER YEAR, HOW WILL
THE POPULATION CHANGE EACH YEAR? (ASSUME THAT
THE POPULATION IS BELOW CARRYING CAPACITY AND
THAT THERE IS NO IMMIGRATION OR EMIGRATION.)
A) It will decrease by 70%.
 B) It will increase by 1%.
 C) It will increase by 5%.
 D) It will increase by 70%.
 E) It will increase by 100%.

READ CHAPTER 15 – ECOSYSTEMS &
COMMUNITIES