Transcript Intro to Ecology

Intro to Ecology
Ecology is the branch of biology that deals
with the interactions between organisms and
the relationship between organisms and the
environment.
No organism exists in nature alone, apart from
it’s environment.
There are levels of organization in an ecosystem:
1. Population
2. Community
3. Ecosystem
4. Biosphere
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Population – all members of a particular
species make up a population. An example
is how all of the water lilies in a pond are
one population and all of the gold fish in a
pond are another separate population.
Community - all of the populations
interacting together make up community. All
of the plants, animals, and microorganisims
in a pond make up a community.
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Ecosystem – includes all of
the members of a community
along with the physical
environment in which they live.
The living and non-living parts
of an ecosystem function
together. An ecosystem is
the structural and functional
unit studied in Ecology.
Biosphere – the portion of the
Earth in which all living things
exist. Water, soil, and air are
included with the living things
in the biosphere.
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What makes an ecosystem?
The ecosystem involves interactions between living
and nonliving things. Two requirements must be
met for a stable ecosystem to exist:
•There must be a constant supply of energy
(sunlight for photosynthesis). There must also be
living organisms that can incorporate the energy into
organic compounds (food). These are autotrophs.
•There must be a recycling of materials between
living organisms and the non-living materials
(environment).
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An ecosystem had both abiotic (non-living) and
biotic (living) parts.
The abiotic factors of an ecosystem include the
physical and chemical factors that affect the
capacity of an organism to live and reproduce.
These factors are:
1. Intensity and duration of light
2. Temperature range
3. Amount of water
4. Type of soil
5. Availability of inorganic substances (minerals)
and gases (O2, CO2, N)
6. pH of soil/water
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Limiting Factors
Abiotic factors vary between
environments. Because the abiotic
factors in an environment determine
which plants/animals live there, they are
called limiting factors.
For example, the amount of water in
a desert limits the kinds of plants and
animals that can live there.
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Biotic Factors
Biotic factors include all of the living things that
directly or indirectly affect the environment.
Thus the organisms, their presence and
parts, interaction, and wastes all act as
biotic factors
These interactions include:
1. Nutritional relationships
2. Symbiotic relationships
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Nutritional Relationships
•Involves the transfer of nutrients from one organism
to another within an ecosystem.
•In terms of nutrition, organisms are either autotrophs
or heterotrophs.
Autotrophs are organisims that can use energy
from the environment to make their own food
from inorganic compounds.
Heterotrophs cannot make their own food and
must obtain nutrients from other organisims.
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Heterotrophs can be classified into one of the
following:
1. Saprophytes are organisms that obtain nutrients
from dead organisms. Bacteria and fungi are
examples.
2. Herbivores are animals that feed exclusively on
plants.
3. Carnivores are animals that consume other animals.
• Predators kill and eat their prey.
• Scavengers feed on the remains of animals that
other animals killed, not them.
4. Omnivores are animals that consume both plant
and animal remains.
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Symbiotic Relationships
• Different organisms may live together in a
close association
• This is known as symbiosis
• There are three types:
1. Commensalism 2. Mutualism
3.Parasitism
• KEY:
+ = benefits
- = harmed
o = not affected
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Commensalism
• (+ , o)
• In this relationship, one organism
benefits and the other is not
affected
• Ex: barnacles on a whale
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Mutualism
• (+ , +)
• In this relationship both organisms
benefit from each other
• Ex: protozoan living in the digestive
tract of termites
• Wood eaten by termites is digested
by the protozoan. The nutrients
released supply both organisms
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Parasitism
• (+ , - )
• In this relationship, the parasite
benefits at the expense of the host
Ex:
• athlete’s foot fungus on humans
• tapeworm and heartworm in dogs
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Producers: Autotrophs that use photosynthesis to make
food
Consumers: All heterotrophic organisms that obtain
energy from the food that they eat.
•Primary Consumers (Herbivores): feed on green plants
and algae
•Secondary Consumers (Carnivores): feed on primary
consumers
•Omnivores eat plants and animals. Humans are
omnivores.
Decomposers: (saprophytes) Break down the remains of
dead organisms and organic wastes. They return the
nutrients to the environment, where they can be recycled
and used again. Bacteria and fungi are examples. The
recycling is essential to an environment so dead remains
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do not accumulate.
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FOOD
WEB
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Food Chains vs. Food Web
• A food chain is the transfer of energy from green
plants through a series of organisms with repeated
stages of eating and being eaten.
• Green plants obtain energy from Sunlight
(photosynthesis) and all other organisms obtain
energy from the breakdown of food.
• In real life most organisms eat more than one
organism and are eaten by more than one
organism, so food chains are interconnected
forming food webs.
• Food webs have the same levels of organisms but
the flow of energy and materials is more complex.
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Food Chains vs. Food Web
• A food chain is the transfer of energy from green
plants through a series of organisms with repeated
stages of eating and being eaten.
• Green plants obtain energy from Sunlight
(photosynthesis) and all other organisms obtain
energy from the breakdown of food.
• In real life most organisms eat more than one
organism and are eaten by more than one
organism, so food chains are interconnected
forming food webs.
• Food webs have the same levels of organisms but
the flow of energy and materials is more complex.
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Pyramid of Energy
•The greatest amount of
energy in a community is
present in the producer
level.
•Only a small portion of this
energy is passed on to
primary consumers, and
only a smaller portion is
passed on to secondary
consumers.
•An energy pyramid can be
used to show the loss of
usable energy at each
feeding (trophic) level.
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Pyramid of Biomass
•In general, the decrease in
available energy at each higher
feeding means that less organic
matter or biomass can be supported
at each higher level.
•Thus, the total mass of producers in
an ecosystem is greater than the
total mass of primary consumers,
and the total mass of primary
consumers is greater than the total
mass of secondary consumers and
so on.
•A biomass pyramid can be used to
show this decrease in biomass at
each higher feeding level.
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Carrying Capacity
•In every ecosystem on Earth, there are limited
amounts of available resources. These include
food, water, energy, minerals, and space.
•The amount of resources available limits the
number of organisms that an ecosystem can
support.
•The maximum number of organisms of a
particular type that can be supported in an area is
known as the carrying capacity.
•If the population increases significantly above it’s
carrying capacity, many individuals die off
because of insufficient resources.
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Competition
• Different species living in the same environment, or
habitat, may require the same resources. When the
resources are limited, competition occurs among the
species.
• Competition- is the struggle between different species for
the same limited resources. The more similar the needs of
the species, the more intense the competition.
• Each species occupies a niche in the community. A niche
is the role the species plays, and includes the type of food
it eats, where it lives, where it reproduces, and its
relationships with other species.
• When two different species compete for the same niche in
a community, the weaker species is usually eliminated
establishing one speciesMrs.
per
niche in a community.
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