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 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)
dNdt = r K −N
K( )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
• ni = number of individuals in species i, N = total number of individuals in the entire community, M = number of species in the community
D =niN
⎛⎝⎜
⎞⎠⎟i
M
∑2
AN EXAMPLE • Compare Community A with 1 species, 100
individuals
• Community B with 3 species, 50, 30 and 20 individuals of each
D =100100
⎛⎝⎜
⎞⎠⎟i
1
∑2
= 1
D =50100
⎛⎝⎜
⎞⎠⎟2⎛
⎝⎜⎞
⎠⎟+
30100
⎛⎝⎜
⎞⎠⎟2⎛
⎝⎜⎞
⎠⎟+
20100
⎛⎝⎜
⎞⎠⎟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
MIN MAX
PARTICLE SIZE
NICHE
MAX
MIN SALI
NIT
Y
A FACT
• Only rarely does the realized niche of an organism approximate its fundamental niche; usually it is smaller