ECOLOGY
•   Def’n: Scientific studies of the interactions that determine the distribution and abundance of organisms

3 LOOKS AT ECOLOGY
•   Levels and principles
•   Population Ecology
•   Conservation Biology

ECOLOGICAL LEVELS
•   Biosphere
•   Biome
•   Ecosystem
•   Community
•   Population
•   Organism
(Individual)

BIOSPHERE
•   Def’n: That portion of the earth where all living organisms reside

BIOME
•   Major terrestrial and aquatic life zones usually named after the dominant vegetation of the region.

FRESH WATER
•   Def’n - less than 500 ppm dissolved salts.

LAKE ZONATION
•   Defined by access to light to support photosynthesis.

MARINE ZONATION
•   Defined by access to light to support photosynthesis.

ECOSYSTEM
Def’n: unique communities of organisms that interact with one another and their surrounding environments in a given area

.
ECOSYSTEM

ECOSYSTEM COMPONENTS
•   Abiotic resources
•   Abiotic conditions
•   Primary producers
•   Consumers
•   Decomposers

COMMUNITY
•   Def’n: Unique assemblage of populations

POPULATION
•   All individuals within a species that exchange genes

BIG PROBLEM FOR
ECOLOGICAL THEORY
•   Connections across levels (bridge laws) d N dt
= r
( )
N

DESCRIPTIVE PARAMETERS
FOR COMMUNITIES
•   Diversity
•   Stability
•   Trophic Structure

DIVERSITY COMPARISON
Community 1 Community 2

COMMUNITY RICHNESS AND
ABUNDANCE
Compare 2 deciduous forests

ANOTHER COMMUNITY
DESCRIPTOR
Compare 2 deciduous forests

ANOTHER COMMUNITY
DESCRIPTOR
•   n i
= number of individuals in species i, N = total number of individuals in the entire community, M = number of species in the community
D
=
M
i
⎝⎜
⎛ n i
N
⎠⎟
⎞ 2

AN EXAMPLE
•   Compare Community A with 1 species, 100 individuals
D
=
1 ∑ i
⎝⎜
⎛ 100
100
⎠⎟
⎞ 2
=
1
•   Community B with 3 species, 50, 30 and 20 individuals of each
D
=
⎝⎜
⎛
⎝⎜
⎛ 50
100
⎠⎟
⎞ 2 ⎞
⎠⎟
+
⎛
⎝⎜ ⎝⎜
⎛ 30
100
⎠⎟
⎞ 2 ⎞
⎠⎟
+
⎛
⎝⎜ ⎝⎜
⎛ 20
100
⎠⎟
⎞ 2 ⎞
⎠⎟
=
0.38

STABILITY
•   Def’n: Ability to return to original composition following perturbation

TROPHIC STRUCTURE
•   Def’n: feeding relationships across the different trophic levels

TROPHIC STRUCTURE
•   Quantitative Food Web

COMMUNITY STRUCTURE
3 DETERMINANTS
•   Historical processes
•   Resource utilization and tolerance
•   Interactions:
–   Competition
–   Predation
–   Symbiotic

RESOURCE UTILIZATION
AND TOLERANCE
MAX
MIN NICHE
MIN
PARTICLE SIZE
MAX

A FACT
•   Only rarely does the realized niche of an organism approximate its fundamental niche; usually it is smaller