Chapter 48, pages 1118-1134
Chapter 49, pages 1145-1165
Ecology-1 0:00-13:17
Ecology-2 0:00-15:10
Ecology-3 0:00-16:03
I. Ecosystems
A. Definitions
1. A network consisting
of organisms, their environment, and all of the
interactions
that
exist in that
environment
2. An interdependent and dynamic biological, physical, and chemical system
B. Examples
1. Simple ecosystem - rock with lichens growing on it
2. Complex ecosystem - pond or tropical rainforest
C. Ecotones - regions of overlap between ecosystems
D. Factors characterizing an ecosystem
a. Physical and chemical factors
(1) Precipitation
(2) Temperature
(3) Sunlight
(4) Humidity levels
(5) Availability of oxygen
(6) Carbon dioxide
(7) Phosphorus
(8) Nitrogen
(1) Organism is fine-tuned genetically to the environment
(2) Zone of Physiological Stress - zone where the organism is uncomfortable
(3) Zone of Intolerance - zone where organism will die
(1) Limits or inhibits physical growth of the organism
(2) Falls outside the range of tolerance and into the zone of intolerance
(3) Environmental factors are bad enough that whole
populations
of organisms
do not survive and the organism becomes
extinct
in that geographic area
a. The living components of the ecosystem - the organisms
b. Organization of the biotic factors
(1)
Species
- different kinds of organisms that live together in a given geographic
region
(2)
Populations
- the number of individuals of a given
species
living in the given
geographic region
(3)
Communities
- The populations of species that are living together in the
given geographic region
c. Niche and Habitat
(1) Habitat
(a) The actual real estate that the organism owns
(b) The kind of neighborhood the organism lives in
(2) Niche
(a) What the organism does for a living
(b) How the organism gets its energy
i)
Interspecific competition - competition between different
species
for
food
ii)
Intraspecific competition - competition between members
of the
same
species for food
(c) Examples of niches:
i) Predation
ii) Commensalism
iii) Mutualism
iv) Parasitism
II. Functioning of Ecosystems
A. Food chains and food webs
1. Food Chains - order in which organisms in an ecosystem are consumed
2. Types of food chains:
b. Decomposer or detritus food chain
3. Two major parts to the grazer food chain:
a.
Producers
- those organisms that
photosynthesize
and store more energy in
food than they consume
b.
Consumers
- those organisms that do not photosynthesize and must eat other
organisms for energy
4. Types of consumers:
a. Heterotrophs - organisms that must eat other organisms for food
b. Herbivores - plant eaters
c. Carnivores - flesh eaters
d. Omnivores - both plant and flesh eaters
B. Classifying consumers by their position in the food chain
1. Primary consumers eat producers
2. Secondary consumers eat primary consumers, etc.
3. Trophic level - level the organism occupies in the food chain
a. First trophic level - producer
b. Second trophic level - primary consumer
C. Thus, the Food Web - all feeding interactions in the ecosystem
D. Flow of energy and matter through the ecosystem
1. Energy flow in the ecosystem
a. Energy - the capacity to do work
(1) First Law - Conservation of Energy
Energy can neither
be created nor destroyed but only
transformed
from
one form to another.
(2) Second Law - Entropy
As energy is lost,
matter becomes more and more disorganized with less
energy trapped within.
(3)
Third Law - energy is degraded (lost) when
it changes form (never 100%
of energy is
transformed)
c.
Conclusion about energy flow in the ecosystem: The total amount
of energy in
any given
trophic
level of the food chain gets smaller and smaller as one
progresses up the
food
chain.
2. Biomass flow in the ecosystem
a. Biomass - the dry weight of all the living organisms at any given trophic level
b.
Each trophic level contains less and less biomass as one proceeds up the
food
chain
3. Flow of numbers of
individuals in the ecosystem - the number of individual organisms
decreases
at each trophic level as one progresses up the food chain
1. Three pyramids can be visualized as it relates to the trophic levels of the food web
2. As the trophic level
increases in number the amount of energy, amount of biomass,
and the number
of individual organisms decrease
F. Productivity
1. Definition - rate of conversion of sunlight to chemical energy (sugar)
2. Definition of units of energy:
a.
Calorie
- amount of heat energy it takes to warm one gram of water one degree
centigrade
b. Kilocalorie
(1) 1000 calories
(2) The unit of energy used in biological systems
3. Productivity measured three different ways:
a. Gross Primary Productivity - GPP
(1) Rate at which sunlight is converted to chemical energy
(2) Kilocalories/square meter/year
b. Respiration rate of producers - R
(1) Energy used by producers for metabolism
(2) This is the energy necessary to maintain life for the producer
c. Net Primary Productivity - NPP
(1) Amount of energy stored by plants
(2) GPP - R = NPP
III. Nutrient Cycles
A. Carbon cycle
D. Water cycle
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