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Population Ecology
Key Concepts
 Factors affecting population size
 Species reproductive patterns
 Species survivorship patterns
 Conservation biology and human
impacts on ecosystems
Population Dynamics and Carrying
Capacity
 Population dynamics
 Biotic potential (intrinsic rate of increase [r])
 Environmental resistance
 Carrying capacity
 Exponential and Logistic Growth
 Population Density
Sampling Populations
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Direct Count
Point Sampling
Transect Sampling
Quadrat Sampling
Mark and Recapture
Population Dispersion
Factors Affecting Population Size
Exponential Growth
Logistic Growth
Environmental
resistance
Population size (N)
Carrying capacity (K)
Biotic
potential
Exponential
growth
Time (t)
Population
overshoots
carrying
capacity
Number of reindeer
2,000
Population
crashes
1,500
1,000
500
Carrying
capacity
1910
1920
1930
Year
1940
1950
2.0
Overshoot
Number of sheep (millions)
Carrying capacity
1.5
1.0
.5
1800
1825
1850
1875
Year
1900
1925
Capture-recapture method interaction.
Click to view
animation.
Population Density Effects
Density-independent controls
Density-dependent controls
Natural Population Curves
The Role of Predation in Controlling
Population Size
 Predator-prey cycles  Top-down control
 Bottom-up control
Reproductive Patterns and Survival
 Asexual reproduction
 Sexual reproduction
Reproductive Patterns and Survival
 r-selected species
Reproductive Patterns and Survival
 K-selected species
Carrying capacity
K
Number of individuals
K species;
experience
K selection
r species;
experience
r selection
Time
Survivorship Curves
Survivorship Curves.
Click to view
animation.
Human Impacts on Ecosystems
 Habitat degradation fragmentation
 Introduction of non-native species
 Pollution
Population explosion of humans
 Overharvesting renewable resources
Human Impacts on Ecosystems
 Ecosystem simplification
 Genetic resistance
 Predator elimination
 Interference with ecological systems
Learning from Nature
 Dependence on Nature
 Interdependence
 Unpredictability
 Limited resources
 Recycle wastes
Solutions
Principles of Sustainability
How Nature Works
Lessons for Us
Runs on renewable solar
energy.
Rely mostly on renewable solar
energy.
Recycles nutrients and wastes.
There is little waste in nature.
Prevent and reduce pollution and
recycle and reuse resources.
Uses biodiversity to maintain
itself and adapt to new
environmental conditions.
Preserve biodiversity by protecting
ecosystem services and preventing
premature extinction
of species.
Controls a species population
size and resource use by
interactions with its
environment and other species.
Reduce births and wasteful resource
use to prevent environmental
overload and depletion and
degradation of resources.
Property
Natural Systems
Human-Dominated
Systems
Complexity
Biologically diverse
Biologically
simplified
Energy source
Renewable solar
energy
Mostly nonrenewable
fossil fuel energy
Waste production
Little, if any
High
Nutrients
Recycled
Often lost of wasted
Net primary
productivity
Shared among many Used, destroyed, or
species
degraded to support
human activities