Download Principles of Ecology Ecological Concepts Biological Organization

Principles of Ecology
So . . .
Chapter 3
“We can't solve problems by using
the same kind off thinkingg we used
when we created them.”
~Albert Einstein
Biological Organization
Ecological Concepts
Ecology: Study of how organisms
interact with each other and with
their non-living
g surroundings.
g
z Environment: Everything that affects
an organism during its lifetime.
z
– Biotic—Living component
– Abiotic—Non-living component
Genes, Populations, and
Species
z
z
z
Genes—Distinct pieces of DNA that
determine an individual’s characteristics.
Population—All organisms of the same
kind found within a specific geographic
region.
Species—Population of all organisms
potentially capable of reproducing
naturally among themselves, and
producing viable offspring.
z
Ecosystems are the most complex
level of biological organization:
cells, tissues, organs, organisms,
populations, communities,
ecosystems
Law of Conservation of
Matter
z
z
z
Although matter can be changed from
one form to another, it can neither be
created nor destroyed by ordinary
physical
h i l and
d chemical
h i l means
There is no such thing as throwing
something “away”
We all have carbon atoms that were in
dinosaurs
Laws of Thermodynamics
First Law = Energy can not be
created nor destroyed; it can be
changed
g from one form to another
z Second Law = When energy is
converted from one form to another,
energy is lost in the form of heat.
z
– Nothing is 100% efficient
Electromagnetic Spectrum
Fate of light impinging on
earth
Food Chains and Food
Webs
photosynthesis
z
Food Chain—Passage of energy from
one trophic level to the next due to
one organism
g
consuming
g another.
z
Food Web—Series of multiple food
chains.
– Some chains rely on detritus.
– A single predator can have multiple
z
6CO2 + 6H2O = C6H12O6 + 6O2
prey species at the same time.
Food Chain - Food Web
Producer : convert about 1% of sun
energy into organic energy
z Consumer: 90% loss of energy loss
at each step
z Decomposer : Recycle energy and
atoms from non-living organic matter
little waste.
z
Fig. 5.15a
Energy Flow Through
Ecosystems
z
z
z
Each step in the flow of energy through an
ecosystem is known as a trophic level.
As energy moves from one trophic level to
the next, most of the useful energy (90%)
is lost as heat. (2nd Law of
Thermodynamics)
Because energy is difficult to track,
biomass (weight of living material) is often
used as a proxy.
Biogeochemical Cycles
All substances in organisms cycle
through ecosystems
z Bulk of substances are not contained
within the bodies of organisms
z Organisms must be able to move
these substances from abiotic into
biotic systems.
z
Carbon Cycle
z
z
z
z
z
Carbon Cycle
Carbon and Oxygen combine to form
Carbon Dioxide.
Plants use Carbon Dioxide during
photosynthesis to produce sugars.
sugars
Plants use sugars for plant growth.
Herbivores eat plants, and incorporate
molecules into their structure.
Respiration breaks down sugars releasing
CO2 and water back into the atmosphere.
Based on atmospheric carbon
dioxide (0.039% of air)
z Plants (and some bacteria) make 70
billion tons of organic compounds
per year
z Carbon dioxide is released into the
atmosphere from respiration
z
Nitrogen Cycle
z
Cycling of nitrogen atoms between abiotic
and biotic ecosystem components.
– Producers unable to use atmospheric N.
z Must get nitrate (NO3) or ammonia (NH3).
– Nitrogen-fixing bacteria converts nitrogen gas
(N2) into ammonia.
z
Plants construct organic molecules.
– Eaten by animals.
– Decomposers also break down nitrogen-
containing molecules releasing ammonia.
Nitrogen Fixers
z
Free living and symbiotic bacteria
z
Ammonification - Conversion of
Nitrogen to NH3 (ammonia). Some
are free living (cyanobacteria) and
some are symbiotic (Rhizobium sp)
Nitrogen fixers - Rhizobium
Nitrifiers
De--Nitrifiers
De
Two different groups of bacteria working
in sequence.
z Organic→ammonia (fungi) →nitrite
(Nitrosomas sp.) → Nitrate (Nitrobacter
sp) → Organic (via plants)
plants).
z Plants can produce all 20 amino acids
z Many animals and humans cannot
produce 8 amino acids
(lysine, tryptophan, threonine, methionine,
z
z
Requires anoxic (no oxygen)
conditions
z
Nitrites to nitrogen gas
z
NH3 → NO2 (Nitrosomas) → N2O
(Pseudomonas, Bacillus) → N2
phenylalanine, leucine, isoleucine, valine.
Phosphorus Cycle
Bulk of phosphorus on earth is in the
ocean … only small amounts in soil
(phosphate rock).
z Needed in life for nucleic acids and
ATP
z Plants take in through roots (PO4)
z Animals eat plants
z Decomposers return it to soil
z
Human Impact on Nutrient
Cycles
z
Two activities caused significant changes
in carbon cycle:
– Burning Fossil Fuels.
– Converting forests to agricultural land.
Fossil fuel burning also increased amount
of nitrogen available to plants.
z Fertilizer carried into aquatic ecosystems.
z
z
Increase aquatic plant growth rate.
– Lowered oxygen concentrations.
Fig. 5.19
Ecological Concepts
z
Limiting factors
– The absence of a key factor needed for
success. Not life, just success.
z
Range of tolerance
– Certain organisms “prefer” certain
environmental conditions.
Habitat and Niche
The “Where” and the “How”
z Habitat: where the organism lives
z Niche: Includes space, food,
temperature, conditions for mating,
g
“job”
j
etc…. The organisms
z Also takes into account behavior at
various seasons or times of the day
z Niche is NOT synonymous with
habitat - habitat is a region, niche is
a functional role
z
Natural Selection Conditions
Natural Selection
– Excess number of individuals results in a
shortage of specific resources.
z
z
Natural Selection—Process that
determines which individuals within a
species will reproduce and pass their
genes to
t th
the nextt generation.
ti
Conditions:
– Individuals within a species show variation.
– Organisms within a species typically produce
huge numbers of offspring, most of which die.
Fig. 5.6
– Due to individual variation, some individuals
have a greater chance of obtaining needed
resources and thus have a greater likelihood
off survival
i l and
d reproduction.
d ti
– As time passes, percentage of individuals
showing favorable variations will increase
while percentage showing unfavorable
variations will decrease.
Kinds of Organism Interactions
Competition
z
Competition—Two organisms compete to
obtain the same limited resource, and
both are harmed to some extent.
Competition
z
– Intraspecific—Members of same species
competing for resources.
– Less fit species must evolve into a
– Interspecific—Members of different species
slightly different niche.
competing for resources.
z
The more similar the competing species,
the more intense the competition.
Predation
z
Competitive Exclusion Principle—No
two species can occupy the same
ecological
g
niche in the same place
p
at
the same time.
Predation—One animal kills/eats
another.
– Predator benefits from food.
z Prey adaptation is manifested in a higher
reproduction rate.
– Prey species benefits by eliminating
non-adaptive genes from the gene pool.
z
Poorly adapted predators are less likely to
obtain food and thus pass on non-adaptive
genes.
Predation
Predation limits the size of
populations
z Prey
y must survive in at least small
numbers or predator becomes
extinct.
z Prey have evolved to have unique
defenses against predators. Moth
eye pattern, cactus, armadillo
z
Community and Ecosystem
Interactions
Community—Assemblage of all
interacting species of organisms in
an area.
z Ecosystem—System of all interacting
organisms, including their non-living
surroundings.
z
Community and
Ecosystem Interactions
z
z
z
z
Major Roles of Organisms in
Ecosystems
Ecosystem Roles
Producers: Make complex from simple
Consumers: rely on producers as food
Primary - herbivores
Secondary - eat primary consumers
Tertiary - carnivores, omnivores,
scavengers, parasites
Decomposers - Eats non-living organic
matter as a source of food
z
Producers—Organisms able to use
sources of energy to make complex
organic
g
molecules from simple
p
inorganic molecules in the
environment.
Roles of Organisms
Roles of Organisms
z
Consumers—Consume organic matter to
provide themselves with energy and
organic matter necessary for growth and
survival.
– Primary Consumers
z Herbivores (plants)
z
Decomposers
– Digest organic molecules in detritus into
simpler organic compounds, and absorb
soluble nutrients. (Bacteria and fungi)
z
z
Use non-living organic matter as source of energy.
Keystone Species
– Play critical role in maintenance of specific
ecosystems.
– Secondary Consumers
z Carnivores (meat)
z Omnivores (plants and meat)
Primary Sucession
Table 5.01
Secondary Sucession