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Ecology
Energy
Flow
Ecosystem Structure
Interactions Among Species
Population Dynamics
Reproductive Patterns

Ecology is a study of
connections in
nature.
◦ How organisms
interact with one
another and with their
nonliving environment.
Figure 3-2
•
Ecosystem- A community of different species interacting together &
with the chemical & physical factors making up its non-living
environment.
•
Species- groups of organisms that can mate and produce fertile
offspring (5 to 100 million on earth).
•
Population- A group of individual organisms of the same species
living w/in a particular area.
•
Communities- The population of all species living & interacting in an
area.
•
Habitat- The place where an organism or a population lives.
•
Niche- The total way of life or role of a species in an ecosystem.
– All the physical, chemical, and biological conditions a species needs to live
& reproduce in an ecosystem.

Organisms, the different forms of life on earth,
can be classified into different species based on
certain characteristics.
Figure 3-3
Ecosystems consist of nonliving (abiotic) and living
(biotic) components that interact together
Figure 3-10
Abiotic – nonliving parts of ecosystems (water,
air, nutrients, solar energy)
1. Range of Tolerance – range of physical and
chemical environments in which a species can
survive.
– Law of Tolerance: the abundance or distribution of
an organism can be controlled by certain factors
– Tolerance Limits: The upper and lower limits to the
range of particular environmental factors within
which an organism can survive.
• Organisms with a wide range of tolerance are usually
distributed widely, while those with a narrow range have
a more restricted distribution.
Abundance of organisms
Upper limit of
tolerance
Few
No
organisms organisms
Population size
Lower limit of
tolerance
No
Few
organisms
organisms
Zone of
intolerance
Low
Zone of
physiological
stress
Optimum range
Temperature
Zone of
physiological
stress
Zone of
intolerance
High
Fig. 3-11, p. 58
2. Limiting Factor – abiotic factors that can
limit or prevent the growth of a population.
– Limiting Factor Principle – too much or too little of
any abiotic factor can limit or prevent the growth of
a population.
Ex. Desert plants (water)
Ex. Aquatic Ecosystems (temp, light,
dissolved oxygen, nutrient
availability, salinity)
Biotic – living parts of ecosystems (plants, animals, and
microorganisms) biota.
1.Producers or Autotrophs (photosynthesis and
chemosynthesis)
• Plants
• Some protists
2.Consumers or Heterotrophs
a.
Herbivores
b.
Carnivores
(secondary or tertiary consumers)
c.
Omnivores
d.
Scavengers
e.
Detritivores
f.
Detritus feeders
g.
Decomposers
3.Important Biotic Processes
• Cellular Respiration – removes oxygen from the
environment and adds carbon dioxide and water.
• Anaerobic Respiration – can add methane gas, ethyl
alcohol, acetic acid, and hydrogen sulfide to the
environment.
• Photosynthesis– removes carbon dioxide and water
from the environment and adds oxygen and water.
Producers◦ An organism that uses solar energy (green plant and
some protists like algae) or chemical energy (some
bacteria) to manufacture its food.
◦ First Trophic Level
◦ Basic source of all food but all energy comes from
the sun
◦ Most producers capture sunlight to produce
carbohydrates by photosynthesis:
Biomass
• Biomass is dry weight of organic matter
produced by plants & represents the chemical
energy stored at each energy level.
• Stems, roots and leaves
• Can be used as electrical energy from wood,
garbage & agricultural waste.
Primary Productivity of Ecosystems
Productivity–the rate at which plants convert solar energy to biomass (NPP)
•
Primary production- The conversion of solar energy to the energy of
chemicals bonds during photosynthesis by autotrophs
•
Secondary production- The total biomass that heterotrophs generate by
consuming autotrophs
Gross Primary Productivity- the energy that results when autotrophs
convert solar energy to chemical energy
High GPPShallow waters near continents
Coral reefs
Forests
Low GPP
Deserts
Polar regions
Open ocean
Net Primary Productivity- what is left of GPP after it is used by an
ecosystems producers to stay alive, grow and reproduce.
- This is the energy or biomass available to consumers in an ecosystem.
High NPP
Estuaries
Swamps and marshes
Tropical rain forests
Low NPP
Open ocean
Tundra
Desert
The earth’s net primary productivity is the upper limit determining the
planet’s carrying capacity for all consumer species.
Our Share of Earth’s NPP
1)
We use, waste or destroy about 27% of earth’s NPP
2)
We use, waste or destroy about 40% of the NPP of terrestrial
ecosystems

GPP = NPP + Respiration
40% of GPP supports the
growth and reproduction
of producers (NPP)
Net Primary
Productivity
Respiration
99% of solar
energy is
reflected or
passes through
producers w/o
being absorbed
Gross
Primary
Productivity
1% of solar energy
striking producers in
captured by
photosynthesis (GPP)
Consumers (heterotrophs) get
their food by eating or
breaking down all or parts
of other organisms or their
remains.
– Primary Consumers
• Second Trophic Level
• Herbivores- eat producers
• Omnivores- feed on both plant
and animals.
– Secondary Consumers
• Third Trophic Level
• Carnivores- Primary consumers
that eat other primary
consumers
– Tertiary Consumers
• Fourth Trophic Level
• Carnivores that eat carnivores.
First Trophic
Level
Second Trophic
Level
Third Trophic
Level
Producers
(plants)
Primary
consumers
(herbivores)
Secondary
consumers
(carnivores)
Heat
Heat
Fourth Trophic
Level
Tertiary
consumers
(top carnivores)
Heat
Solar
energy
Heat Heat
Heat
Heat
Heat
Detritivores
(decomposers and detritus feeders)
Fig. 3-17, p. 64




Scavengers- consume dead animals
Detritivores- Specializes in breaking down dead
tissues and products into smaller particles- insects
Decomposers- Fungi and Bacteria that digests
parts of dead organisms, cast-off fragments, and
wastes of living organisms and recycles those
nutrients back into the environment
Detritus feeders- eat off of partially decomposing
materials such as leaf liter, animal dung or plat
debris
Decomposition
 As plant or animal matter dies it will break
down and return the chemicals back to the
soil.
 This happens very quickly in tropical
rainforest which results in low-nutrient soils.
 Grasslands have the deepest and most
nutrient rich of all soils
Ecological efficiency:
percentage of
useable energy
transferred as
biomass from one
trophic level to the
next.
Figure 3-19
10% Rule



We assume that 90% of the energy at each
energy level is lost because the organism uses
the energy. (heat)
It is more efficient to eat lower on the energy
pyramid. You get more out of it!
This is why top predators are few in number &
vulnerable to extinction.
 Shows
the decrease in usable
energy available at each
succeeding trophic level in a
food chain or web.
Food Chains- determines how energy &
nutrients move from one organism to another
through the ecosystem
 Arrows – point from the producer to the
consumer
Food WebsInterconnected
food chains that
shows all possible
energy transfers
within an
ecosystem