Transcript Interactions: Environments and Organisms Chapter 5 1

Interactions: Environments and
Organisms
Chapter 5
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Ecological Concepts
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__________ - Study of ways organisms
interact with each other and with their nonliving surroundings.
__________ - Everything that affects an
organism during its lifetime.
– Biotic - ___________________
– Abiotic - ______________________
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Levels of Organization in Ecology
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Ecological Concepts
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____________ - Any factor whose shortage or
absence restricts species success.
– Range of Tolerance - Range of conditions an
organism can survive in.
 Temperature
 pH
 DO
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Habitat and Niche
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_______ - Space an organism inhabits; defined
by biological requirements of each particular
organism.
– Usually highlighted by prominent physical or
biological features.
Niche - __________________________________
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Includes all ways an organism affects
organisms with which it interacts as well as
how it modifies its physical surroundings.
Fig. 5.3
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Ecological Niche
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Genes Population and Species
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________ - Distinct pieces of DNA that
determine the characteristics an organism
displays.
Population ____________________________________
____________________________________
– Contains more kinds of genes than any
single individual within the population.
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Genes Population and Species
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Species ____________________________________
____________________________________
____________________________________
____________________________________
– Working definition that only applies to
organisms that sexually reproduce.
 Some species are easy to recognize,
while others are more difficult.
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Natural Selection
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______________ - Process that determines
which individuals within a species will
reproduce and pass their genes to the next
generation.
Conditions:
– Individuals within a species show
genetically determined variation.
– Organisms within a species typically
produce huge numbers of offspring,
most of which die.
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Natural Selection Conditions
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Excess number of individuals results in
a shortage of specific resources.
Due to individual variation, some
individuals have a greater chance of
obtaining needed resources and thus
have a greater likelihood of survival and
reproduction.
As time passes, percentage of
individuals showing favorable variations
will increase while percentage showing
unfavorable variations will decrease.
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Evolutionary Patterns
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__________ - A change in the kinds of
organisms that exist and in their
characteristics.
– Ex. Building tolerance to pesticides.
Speciation ____________________________________
____________________________________
– Thought to occur as a result of a species
dividing into two reproductively isolated
subpopulations.
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Evolutionary Patterns
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Extinction - Loss of entire species.
– Of estimated 500 million species
believed to have ever existed on earth,
98-99% have gone extinct.
__________ - Two or more species can
reciprocally influence the evolutionary
direction of the other.
– Grazing animals and grass species.
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Kinds of Organism Interactions
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Predation _____________________________________
_____________________________________
 Prey adaptation is manifested in a
higher reproduction rate.
 Fig. 5.7
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Kinds of Organism Interactions
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Prey species benefits by eliminating
non-adaptive genes from the gene pool.
 Poorly adapted predators are less
likely to obtain food and thus pass on
non-adaptive genes.
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Competition
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Competition - Two organisms strive to obtain the
same limited resource, and both are harmed to
some extinct.
– ___________ - Members of same species
competing for resources. (Mice for Cheese)
– ___________- Members of different species
competing for resources. (Fox & Hawk for Mice)
The more similar the competing species, the
more intense the competition.
Fig. 5.8
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Competition
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______________________ - No two species
can occupy the same ecological niche in
the same place at the same time.
– Less fit species must evolve into a
slightly different niche.
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Symbiotic Relationships
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___________ - Close, physical relationship
between two different species. At least one
species derives benefit from the interaction.
– Parasitism ______________________________________
______________________________________
______________________________________
 Ectoparasites - Live on host’s surface.
 Fleas
 Endoparasites - Live inside host.
 Tapeworms
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Symbiotic Relationships
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Commensalism - One organism benefits while the
other is not affected.
– Remoras and Sharks
___________ - Both species benefit. Obligatory
in many cases as neither can exist without the
other.
– Mycorrhizae
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Community and Ecosystem
Interactions
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Community - Assemblage of all interacting
species of organisms in an area.
__________ - Defined space in which
interactions take place between a
community, with all its complex
interrelationships, and the physical
environment.
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Major Roles of Organisms in
Ecosystems
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Producers - Organisms able to use
sources of energy to make complex
organic molecules from simple inorganic
molecules in the environment.
– Ex. Grasses, Trees, Moss, Ferns
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Roles of Organisms
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__________ - Consume organic matter to
provide themselves with energy and
organic matter necessary for growth and
survival.
– Primary Consumers
 Herbivores (plants)
– Secondary Consumers
 Carnivores (animals)
 Omnivores (plants and animals)
– Scavengers (dead animals)
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Roles of Organisms
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_______________
– Digest organic molecules in detritus into
simpler organic compounds, and absorb
soluble nutrients. (Bacteria and Fungi)
 Use non-living organic matter as
source of energy.
Keystone Species
– Play critical role in maintenance of
specific ecosystems.
 Bison in American Tall Grass Prairie
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Energy Flow Through Ecosystems
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Each step in the flow of energy through an
ecosystem is known as a ___________.
– 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.
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Energy Flow Through an Ecosystem
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Food Chains and Food Webs
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_________ - Passage of energy from one
trophic level to the next due to one
organism consuming another.
– Some chains rely on detritus.
_________ - Series of multiple, overlapping
food chains.
– A single predator can have multiple prey
species at the same time.
– Fig. 5.15
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Food Chain
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Nutrient Cycles in Ecosystems
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Organisms are composed of molecules
and atoms that are cycled between living
and non-living portions of an ecosystem.
– Biogeochemical Cycles - another name
for nutrient cycles.
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Carbon Cycle
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Carbon and oxygen combine to form
carbon dioxide.
– Plants use carbon dioxide during
photosynthesis to produce 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.
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Carbon Cycle
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Nitrogen Cycle
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Cycling of nitrogen atoms between abiotic and
biotic ecosystem components.
– Producers unable to use atmospheric N.
 Must get nitrate NO3 or ammonia NH3.
– ___________________ converts nitrogen gas
N2 into ammonia. Legumes (Roots)
 Plants construct organic molecules.
 Eaten by animals.
 Drains soil of Nitrogen.
– Decomposers also break down nitrogencontaining molecules releasing ammonia.
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Nitrogen Cycle
Nitrifying bacteria are able to convert
ammonia to nitrite, which can be
converted to nitrate.
Denitrifying bacteria are able to (under
anaerobic conditions) covert nitrite to
nitrogen gas (N2) which is ultimately
released into the atmosphere.
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Nitrogen Cycle
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Phosphorus Cycle
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Phosphorus is not present in the
atmosphere as a gas.
– Phosphorus compounds released by
erosion and become dissolved in water.
 Plants use phosphorus to construct
necessary molecules.
 Animals gain necessary P via
herbivory.
 Decomposers recycle into soil.
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Phosphorus Cycle
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Human Impact on Nutrient Cycles
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Two activities caused significant changes
in carbon cycle:
– Burning of fossil fuels. (2001 – IPCC
Report)
Converting forests to agricultural land.
Fossil fuel burning also increased amount
of nitrogen available to plants.
Fertilizer carried into aquatic ecosystems.
 Increase aquatic plant growth rate.
 Lowered oxygen concentrations.
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Review
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Ecological Concepts
– Habitat and Niche
Natural Selection and Evolution
Organism Interactions
– Predation
– Competition
Community and Ecosystem Interactions
– Roles of Organisms
– Energy Flow Through Ecosystems
– Nutrient Cycles in Ecosystems
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