2. Population Ecology
The study of individual
species in relation to the
environment.
The field is concerned
with conservation and
focuses on Population and
Population Viability
Analysis (PVA)
3. Population Viability Analysis
A species-specific method of
risk assessment.
Brings together species
characteristics and
environmental variability to
forecast population health and
extinction risk.
Begins with the question: “Is this
species at risk of becoming
endangered? If so, why?”.
A research example may
include: “What are the effects
of industrial forestry on
biodiversity.”
4. WHAT ARE THE MAJOR
CHARACTERISTICS OF A
POPULATION?
5. Populations
A group of individuals of a single species that
simultaneously occupy the same general area.
10. Biogeography
The study of the size and
distribution of biodiversity
over space and time. It
aims to reveal where
organisms live, and at
what abundance.
Giant Pandas
11. Factors Explaining Species Distributions
Speciation
Extinction
Continental drift
Glaciations
(associated variations
in sea level, river
routes)
River capture
13. Paleobiogeography
goes one step further
to include
paleogeographic data
and considerations of
plate tectonics.
Uses molecular
analyses and fossils to
determine the change
in a species over
millions of years.
Hominid Evolution
15. Mark-Recapture Method
A method commonly used in ecology to estimate population
size and population vital rates (i.e., survival, movement, and
growth)
17. The Process
Researcher visits a study area and uses traps to
1.
capture a group of individuals alive.
Captured animals are marked with tags, collars,
2.
bands, or spots of dye and then is released
unharmed back into the environment.
Sufficient time is allowed to pass for the marked
3.
individuals to redistribute themselves among the
unmarked population.
Next, the researcher returns and captures another
4.
sample of individuals.
22. Factors Affecting Distribution
Density Dependant Density Independent
Competition for Floods
Resources Hurricanes
Predation Unseasonable
Weather
Parasitism
Infectious Disease Fire
Clear Cutting
Pesticide Spraying
23. Changing and Clumping
Availability and variation
of resources
Provide protection in
numbers
Packs have a better
chance of obtaining food
Temporary groups for
mating
24. Factors that Govern Population Size
Crude Birth Rate (CBR)
Crude Death Rate (CDR)
Immigration
Emigration
Population Change = (births + immigration) – (deaths + emigration)
29. Population growth strives for dynamic equilibrium:
Logistic Growth of a Sheep
2.0
Number of sheep (millions)
1.5
1.0
.5
1800 1825 1850 1875 1900 1925
Year
30. Organisms can exceed their carrying capacity:
Exponential Growth and Crash of Reindeer
2,000
Number of reindeer
1,500
1,000
500
1910 1920 1930 1940 1950
Year
31. Reasons for Diebacks
Catastrophic Loss of Resources
Introduction of New Predator
Disease
32. WHAT KINDS OF POPULATION
CHANGE CURVES DO WE FIND
IN NATURE?
34. Cycles in Hare and Lynx
Populations
160
140 Hare
Population size (thousands)
120
Lynx
100
80
60
40
20
0
1845 1855 1865 1875 1885 1895 1905 1915 1925 1935
Year
35. Community Organization –
Trophic Cascade Model
Postulates that it is mainly predation that controls
community organization
Predators control herbivores
36. Community Organization –
Bottom-Up Model
Mineral nutrients control community organization
Nutrients control plant types and numbers
Plants control predators
Changes in this community are done by adding or
removing minerals
37. Activity: Radio Expeditions
Species Extinctions
Audio Evidence of Ivory-Billed Woodpecker
http://www.npr.org/templates/story/story.php?storyId=4814860
Audubon Bird Count, Lost Woodpecker Rediscovered
http://www.npr.org/templates/story/story.php?storyId=5067655
Slate's Explainer: Determining Species Extinction
http://www.npr.org/templates/story/story.php?storyId=5015201
38. Activity: Radio Expeditions
Species Extinctions Questions
Populations are classified by size, density, age distribution, and dispersion
type. Briefly explain each of these concepts and describe one
environmental factor that would limit the population growth of a bird
species.
Discuss the difference between an endangered and a threatened species.
Design a population count experiment to determine if a bird population is
threatened or endangered. Make sure to discuss how the study area was
selected and what method will be used to estimate population.
Discuss one biological intervention, economic incentive and one legislative
policy to restore an endangered bird population.
Discuss what technology could be used to periodically monitor the program.
42. General Characteristics of r-Selected Species
cockroach dandelion
r-Selected Species
Many small offspring
Little or no parental care and protection of offspring
Early reproductive age
Most offspring die before reaching reproductive age
Small adults
Adapted to unstable climate and environmental
conditions
High population growth rate (r)
Population size fluctuates wildly above and below
carrying capacity (K)
Generalist niche
Low ability to compete
Early successional species
43. General Characteristics of k-Selected Species
K-Selected Species
elephant saguaro
Fewer, larger offspring
High parental care and protection of offspring
Later reproductive age
Most offspring survive to reproductive age
Larger adults
Adapted to stable climate and environmental
conditions
Lower population growth rate (r)
Population size fairly stable and usually close
to carrying capacity (K)
Specialist niche
High ability to compete
Late successional species
44. Carrying Capacity of Species
Carrying capacity
K
K species;
experience
Number of individuals
K selection
r species;
experience
r selection
Time
45. WHAT ROLE DOES GENETICS
PLAY IN THE SIZE OF
POPULATIONS?
46. Vulnerability of Populations
Founders Effect
Results from the migration of a population to a geographically
isolated area.
Demographic Bottleneck
Results from a natural catastrophe such as fire or a hurricane.
Genetic Drift
Results from random changes in the gene frequencies in a population.
Interbreeding
Results when individuals from a small population breed with each
other.
47. HOW DO ECOLOGISTS USE
LIFE TABLES AND
SURVIVORSHIP CURVES TO
MONITOR POPULATIONS?
48. Death Will Come:
Survivorship Curves
Late Loss
Early Loss
Percentage surviving (log scale)
100
Constant Loss
10
1
0
Age
49. Life Table
Life Expectancy at Birth of Epidemic Malaria Area in Papua New Guinea
An age-specific summary of the
survival pattern of a population.
Life tables are constructed by
following a cohort from birth to
death.
A cohort is a group of individuals
of the same age.
The table is constructed from the
number of individuals that die in
each age-group during a
defined time period.
Life tables are graphically
displayed in survivorship curves.
50. Geographical Information Systems
Used to Map Population Data
Captures, stores, analyzes,
manages, and presents data
that refers to or is linked to
location.
Geographic information system
technology can be used for
scientific investigations for the
environmental science,
environmental impact
assessment, urban planning and
other purposes.
Can be used for spacial
analysis and data modeling.
