Ecological Principles

1
Ecological Principles
PaCES/HIMB Summer Program in Environmental
Science David A. Krupp, Ph.D

• Part I

2
Topics to be Studied

• Define ecology and describe its scope
• Define essential terms
• Contrast biotic and abiotic factors
• Physiological limits and abiotic factors
• Biomes
• Population characteristics
• Population growth

3
Ecology

• Ecology the study of the interaction of
  organisms with their environments.
• It involves understanding biotic and abiotic
  factors influencing the distribution and
  abundance of living things.
• The word "ecology" coined from Greek word
  "oikos", which means "house" or "place to live.

4
The Scope of Ecology

• Population growth
• Competition between species
• Symbiotic relationships
• Trophic ( feeding) relationships
• Origin of biological diversity
• Interaction with the physical environment
• Ecosystem change
• Human impacts on the environment

5
Some Important Terms

• Population
• A collection of individuals all belonging to the
  same species in a defined area and time
• Community
• A group of interacting populations in a defined
  area and time

6
Some Important Terms

• Ecosystem
• A system composed of the biological community
  interacting with its surrounding abiotic
  environment
• Biosphere
• The entire portion of the Earth in which life
  occurs all of the ecosystems of the Earth
  combined

7
Biotic Factors

• Dispersal
• Behavior
• Species interactions
• Competition for common resources
• Predator-prey relationships
• Symbiotic associations

8
Abiotic Factors

• Temperature
• Water
• Light
• Salinity
• Wind
• Currents
• Substrate

9
Physiological Limits
environmental gradient
10
Physiological Limits
zone of tolerance
11
Physiological Limits
zones of intolerance
12
Physiological Limits
optimum range
13
Physiological Limits
zones of physiological stress
14
Biomes

• Biomes major types of ecological assemblages
  that occupy broad geographic regions of land or
  water
• Aquatic biomes primarily influenced by depth
  (light) and temperature
• Terrestrial biomes primarily influenced by
  temperature and balance between precipitation and
  evaporation

15
Aquatic Biomes Lakes
oligotrophic
eutrophic
16
Aquatic Biomes Wetlands
17
Aquatic Biomes Streams and Rivers
18
Aquatic Biomes Estuaries
19
Aquatic Biomes Intertidal
20
Aquatic Biomes Oceanic Pelagic Biome
21
Aquatic Biomes Coral Reefs
22
Aquatic Biomes Marine Benthic Zone
23
Terrestrial Biomes
24
Terrestrial Biomes Tropical Forests
25
Terrestrial Biomes Deserts
26
Terrestrial Biomes Savanna
27
Terrestrial Biomes Chaparral
28
Terrestrial Biomes Temperate Grasslands
29
Terrestrial Biomes Coniferous Forest
30
Terrestrial Biomes Temperate Broadleaf Forest
31
Terrestrial Biomes Tundra
32
Population Characteristics

• Size and density
• Dispersion
• Survivorship
• Population growth
• Population age structures

33
Density

• Number of individuals per unit area, per volume
  or unit of habitat.

34
Dispersion Patterns
35
Dispersion Patterns
36
Dispersion Patterns
37
Population Growth
38
Exponential Population Growth
39
Population Growth
Population Size (N)
40
Population Growth
?N/?t B - D
dN/dt bN - mN
dN/dt instantaneous rate of population increase
b per capita birth rate m per capita
mortality rate
dN/dt (b - m)N rN
r b - m
41
Population Growth
dN/dt rN
r per capita rate of increase
Under Optimal Conditions
dN/dt rmaxN
rmax optimal per capita rate of increase
42
Effects of Different Intrinsic Growth Rates (r)
rmax 0.5
rmax 1.0
43
Density-Dependent Growth The Logistic Growth
Model
44
Population Growth

• A Paramecium population in the lab

45
Population Growth

• A Daphnia population in the lab

46
Population Growth

• A sparrow in its natural habitat

47
Density-Dependent Factors

• limiting resources (e.g., food shelter)
• territoriality
• production of toxic wastes
• infectious diseases
• predation
• stress and other intrinsic factors
• emigration

48
Density-Independent Factors

• severe storms and flooding
• sudden unpredictable severe cold spells
• earthquakes and volcanoes
• catastrophic meteorite impacts