Transcript Introduction to Ecology1

Introduction
• Our past ancestors stood on the face of this Earth with
the belief that it was a tremendously large and flat world.
• The Earth, in their view, was the center of the universe.
• People believed humans were totally unrelated to other
animal life here on Earth; that humans were placed on
this earth to rule over and make use of the boundless
resources, put here for the sole benefit of humans.
Water, land, air, minerals, forests, fish, and all other
resources, both renewable and non-renewable, were all
considered to be in endless supply.
Paradigm
The way that humans view the world is known as a
paradigm.
• "The earth and all things on it exist for the sole
benefit of humans" was an old world paradigm.
This paradigm was the reason that western
civilization was created on the premise of
unlimited exploitation of the earth!
• Today it is clearly understood by most people
that the early views were wrong.
• The old paradigms have been replaced by new
paradigms.
Paradigm Shift
• Changes in paradigms are known as paradigm shifts.
Humans no longer regard the Earth as the centre of the
universe.
• Humans now recognize that the Earth is a sphere rather
than flat.
• The Earth's resources are not in endless supply for our
plunder.
• We are the caretakers of this world and we must take
responsibility for its sustainability.
• These are all examples of paradigm shifts.
• The paradigms of modern man differ from the paradigms
of our forefathers.
Sustainability
• The modern paradigm views the Earth as
a sustainable system provided that
renewable resources are not used at a
faster rate than they are replaced or
recycled.
• The term sustainability means that the
system can meet the needs not only of our
present human population, but also those
of the future.
Introduction to Ecology
• Is the scientific study of the interactions of
organisms and their environment
• Interactions of organisms and their
environment includes how the
environment affects the organism and how
the organism affects the environment
• Ecosystem – is a community of
organisms and their physical environment
• An ecosystem is a community made up of
animals, plants, and micro-organisms, together
with the environment where they live.
• Members of the community depend on each
other and their environment for food and shelter.
• Ecosystems have four main components: air,
water, land and living creatures.
• Every ecosystem on Earth depends on water, of
varying amounts, for its survival.
Abiotic Factors
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Space
Temperature
Oxygen
Sunlight
Water
Inorganic and organic soil nutrients
Biotic Factors
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Detritus
Disease
Predator\Prey interactions
Competition
Symbiotic Relationships
• Are biotic relationships in which two or more organisms
live in close association with each other to the benefit of
at least one
• Five types
– Mutualism – results in mutual benefit to both organisms
– Commensalism – one organism benefits the other neither
benefits nor is harmed
– Parasitism – one organism benefits and the other one is harmed
– Parisitoidism – one benefits but the other is eventually killed
– Predation – the interaction is beneficial to one and the other is
killed
Mutualism
Predation
Commensalism
Parasitism
Parasitoids
Trophic Structure
• Each step in the food chain is called a trophic level
• Refers to the feeding relationships within the ecosystem
• Five levels
1. Primary producers – also called autotrophs – they produce their own
food
• Consumers – heterotrophs – organisms that eat other organisms
• 4 types of consumers
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Herbivores – eat plants
Carnivores – eat animals
Omnivores – eat both plants and animals
Saprobes – decomposes – eat dead plants and animals
2. Primary consumers – feed directly on plants
3. Secondary consumers –feed on primary consumers
4. Tertiary consumers – top consumer because it is at top of food chain
5. Decomposers
Trophic Structure (cont’d)
• Feeding relationships within an ecosystem
are generally called a food web
• The food web consists of all the possible
food chains within the ecosystem
Your Turn
• Read pg. 8 – 13
– Questions Pg. 13 # 1,2,3,4(a)(c)
• Read pg. 22 – 23
– Questions Pg. 23 # 1 – 6
• Read pg. 34 – 39
– Questions Pg. 39 # 1 -7
• Pg. 46 # 6
Succession
• Ecological succession refers to the series of ecological changes
that every community undergoes over long periods of time.
• succession begins with relatively few pioneering plants
• The plant life serves as food, and often shelter for the animal life that
can survive in that environment.
• succession in the plant life is paralleled by a succession in animal
life.
• as a result succession, a primitive community develops.
• organisms that make up the primitive community gradually change
the environmental conditions so each successive community paves
the way for the next.
• Each successive community becomes more complex until it
becomes a final, sustainable, stable community called a climax
community.
• In an ecosystem with a climax community, the conditions continue to
be suitable for all the members of the community.
• The climax community is the final stage of ecological succession.
Primary Succession
• primary succession occurs in an area where there is no soil or
previous forms of life.
• occurs in an area such as a freshly cooled lava field, or a newly
formed sand dune.
• on land, primary succession is a very slow process because it
begins with the formation of soil.
• The soil forms as a result of weathering and the action of pioneer
organisms.
• Large rocks are broken down into smaller pieces and eventually
bacteria, fungi, and lichens inhabit the area. T
• these organisms are known as pioneer organisms because they
are the first type of life to inhabit the region.
• The pioneer organisms add organic matter to the
primitive soil, changing the conditions of the
microenvironment so that mosses, ferns, and other
primitive plants begin to take over.
• Grasses may eventually replace the more primitive
plants and when they die, they make the soil even richer.
• Shrubs grow and shade the grass causing it to die.
• Then trees may grow and shade out the shrubs.
• Seedlings of other trees may grow well in the shade.
• In this way, one community of trees will be succeeded by
another community with different trees.
Secondary Succession
• Secondary succession occurs in an area in which an
existing community has been partially destroyed and its
balance upset, either by natural causes, such as fire, or
as a result of human activity, such as the cutting of a
forest, or abandoning a farm.
• The major difference between primary and secondary
succession in a terrestrial environment is that in
secondary succession, soil already exists. S
• seeds of plants will begin to grow.
• Those that do grow will come from dormant seed already
in the soil, or will come from plants in communities
nearby.
• The seeds will establish a community but succession will
eventually result in a climax community that is often the
same as would normally be found in the typical climax
community in the region.
• An abandoned farm may become a forest given enough
time.
• The final climax community is generally the same as the
climax community that surrounds the disturbed area.
• The series of stages leading to the climax community will
not be the same as for a primary succession that created
the original climax community.
Factors that contribute to
ecological succession:
• The type of climax community that is established
will depending on the environmental conditions
of the area.
• The most important environmental conditions
that affect succession include:
– climate (temperature, precipitation, and availability of
sunlight),
– soil (salinity, fertility, moisture, texture, etc.),
– and geographical features (latitude, altitude, and
proximity to mountain ranges or large bodies of
water).
• Every ecosystem exists because there is a
balance between its members (producers,
herbivores, omnivores, predators, scavengers,
parasites, competitors, decomposers, etc.) and
its abiotic environment (climate, soil, availability
of sunlight, pH, oxygen levels, salinity, etc.).
• It is this balance between the biotic and abiotic
factors that creates the stability of the
ecosystem.
• In general, the greater the biodiversity, the
greater the stability.
Your Turn
• Search the web to find at least one example to illustrate
either primary succession or secondary succession.
Prepare a presentation, including a sequence of
diagrams or images, to describe the changes that occur
during succession and lead to the formation of a climax
community. Your series of diagrams or images should
identify the different types of plant and animal life found
at each stage in the process, and clearly identify the type
of climax community formed at the end of the process of
succession. You presentation should include answers to
each of the following questions:
• What is succession?
• What factors contribute to succession?
• What are the characteristics of a climax community?
Energy Flow in Ecosystems
• Vast majority of all life on earth depends
on sunlight as its source of energy
• Actual amount of light that reaches the
surface of the earth id affected by the
albedo effect
• The albedo effect is a measure of the
amount of light reflected from an object
Energy Flow in Ecosystems
(cont’d)
Photosynthesis is a biological process whereby
the suns energy is used by green plants to
manufacture sugar – oxygen is also produced
Carbon dioxide + water + sunlight = sugar + oxygen
The sugar that is produced serves as the
source of energy for nearly all life.
The passage of food from producer to various
consumers is called a food chain
Energy Flow in Ecosystems
(cont’d)
• The transfer of energy through an
ecosystem is never 100% efficient since
each organism must use some of the
energy for its own existence.
Energy Flow in Ecosystems
(cont’d)
• The energy budget or the amount of
energy that is available to an ecosystem
depends on its producers
• Ecologists have adapted the 10 % rule,
put simple “ only 10% of the available
energy at one trophic level is passed on to
the next level”
Energy Flow in Ecosystems
(cont’d)
Example
Corn – primary producer -10 000 J
Mouse – primary consumer - 1 000 J
Snake – secondary consumer - 100 J
Hawk – tertiary consumer - 10 J
The idea that each higher trophic level has less
energy available is known as the pyramid of
energy
Energy Flow in Ecosystems
(cont’d)
Hawk
Snake
Mouse
Corn
Pyramid of Energy
Pyramid of Biomass
• Since the amount of water present within the tissues of
different organisms varies, biologists use the dry mass of
the organism for comparison since it is believed that dry
mass more closely reflects the actual amount of "living
matter" in the organism.
• The dry mass is known as biomass. The availability of
energy will also affect the number of organisms and the
mass of the organisms at each trophic level.
• In general, the higher the amount of available energy
the higher is the biomass (dry mass) at each trophic
level.
• The pyramid of biomass is a graphical representation
of the total biomass of all the members of each trophic
level.
• Generally the pyramid of biomass has the same shape
as the pyramid of energy.
Pyramid of Numbers
• The pyramid of number is the third type of graphical
representation used by biologists to study ecosystems.
• The pyramid of number is often similar in shape to the
pyramid of energy or biomass, but there are exceptions.
• Consider a single spruce tree in a boreal forest (biomass
= 100 kg) which is infested by 100,000 spruce bud
worms (total biomass = 10 kg), which are in turn eaten
by 5 insect eating birds (total biomass = 1 kg).
• The pyramid of biomass would appear normal (base
representing 100 kg, middle piece representing 10 kg,
and a top piece representing 1 kg).
• The pyramid of number for this example will not look
normal.
• The pyramid of number would have a very small base
representing the producer (1 tree), a very large herbivore
level (100,000 spruce bud worms), followed on top by a
small predator level (5 birds).
Your Turn
• Pg. 39 # 9 - 14
#9
• Less than 10% of the energy in a
produces is transferred to a primary
consumer because it uses the rest to carry
on photosynthesis, grow new tissue,
reproduce, etc.
# 10
• The mouse uses some of the energy ot
acquired from its plant food in metabolism,
growth, locomotion, etc
# 11
• To construct a pyramid of numbers, you
would have to count all of the organisms
in the population making up the food chain
# 12
• A pyramid of numbers does not show
energy flow because of the potential
disparity in the sizes of the organisms.
• It is not a good indicator of the health of an
ecosystem
# 13
• A pyramid of energy for a grassland in
winter would show considerably less
energy at the producer level than a
grassland in the summer. The grassland
receives less solar energy in the winter
than in the summer.
• Day is shorter and covered by snow
# 14
• The pyramid of numbers for a deciduous
forest has a small base because it doesn’t
take many trees to produce a large
biomass.
• The large biomass is shown by the large
base of the pyramid of biomass.
• Niche, refers to the role that a species plays
within its ecosystem. In balanced ecosystems,
each species occupies its own niche. The niche
is like the organism's profession - what it does to
survive.
• Habitat refers to the place were an organism
lives. The habitat of a species is different than its
niche, it is the particular part of the environment
in which it lives. The habitat of an organism is
part of its niche. The organism's habitat is its
address - where it lives.
Competition
• Competition between organisms exists in every
ecosystem.
• Organisms are forced to compete against their own
species and also different species in order to survive.
• The stronger and more fit organisms have a better
chance of surviving.
• Competition arises when organisms have requirements
in common and they must compete to meet their own
needs.
• The more needs organisms have in common, the more
intense the competition.
• When the resources that are being competed for
become scarce the competition becomes more intense,
and eventually one of the species becomes eliminated.
• Competition between the same species is
called intraspecific competition.
– Ex. birds of the same species compete for
the best nesting grounds.
• Competition between different species is
called interspecific competition.
– Ex. the lion and the hyena both compete for
zebra.
Your Turn
• Pg. 44 # 1 - 3
Pests and Pesticides
• Pests are living organisms that are not
wanted around us.
• Examples of pests include dandelions
,rodents or insects
• A pest is any organism that man believes
is undesirable, has a negative impact on
the human environment, or is in
competition with human use of a resource,
either natural, or cultivated.
Early Pesticide Use:
• Early pesticides included the use of toxic inorganic
metallic salts such as copper sulfate, lead salts, arsenic,
or mercury.
• These substances were generally effective against the
intended pest, but also created some environmental
problems because they also killed other beneficial
organisms, and polluted water and soil resources used
by man.
• Most early pesticides were non-biodegradable (meaning
that they were not broken down within the ecosystem).
• As a result, these early pesticides began to accumulate
in the environment, contaminating water and soil
resources, eventually poisoning humans.
Modern Pesticides:
• chemists began to develop organic pesticides that were
designed to be less toxic to man and more specific
toward the intended pests.
• It was soon discovered that the organic pesticides also
caused unexpected environmental effects.
• Some of these pesticides were fat soluble.
• This characteristic lead to a problem known as
bioaccumulation.
• As each organism feeds on one lower in the food chain,
the fat soluble pesticide began to be concentrated in
ever higher amounts as one moved toward the top of the
food pyramid.
• Since every organism eats far more than its own
body mass in food, the tiny amounts found in
each organism in the lower levels of the food
web began to accumulate in greater
concentrations in species located at higher
trophic levels.
• One example of this problem is illustrated by the
damage done to predatory birds as a result of
bioaccumulation of DDT.
• As a result of this problem DDT has been
banned from use in North America.
Your Turn
• Read pg. 52 – 58
• Answer questions # 1 - 10
Biochemical Cycles
• oxygen, carbon, hydrogen and nitrogen make up
the vast majority of living tissue.
• These four elements are recycled between living
organisms and the soil, water and atmosphere
• These elements are first taken up by plants,
converted into food, passed through the food
web, consumers and decomposers, then
returned to the environment in a continuous
recycling of materials.
• If recycling of these materials did not occur, life
could not exist.
• continuation of life depends on the continued recycling
• Some elements (carbon, oxygen, sulfur, nitrogen) are
found in gaseous forms and their cycles involve the
atmosphere. As a result they have a global nature.
• some of the elements may have a short term cycle such
as when carbon is transferred from animals to plants in
the form of carbon dioxide and a long term cycle such as
the transfer of carbon from a fossil fuel to a plant
following combustion.
• elements are cycled between the living organisms and
the environment (both long and short term).
• It is a combination of biological and geological processes
that drives chemical recycling
• The elements are cycled between the
living organisms and the environment
(both long and short term). It is a
combination of biological and geological
processes that drives chemical recycling.
Biological Processes
– respiration
– decomposition
– excretion
– photosynthesis
– and assimilation
Geological Processes
– fossilization
– erosion
– combustion of fossil fuels (peat, oil, coal)
– weathering
– formation of sedimentary rock
Carbon Cycle
Your Turn
• Read 2.5 "The Carbon Cycle" on pages 62
- 65. Answer questions 1 - 7 from
"Understanding Concepts" and "Making
Connections" on page 65.
Your Turn
• Read 2.6 "The Nitrogen Cycle" on pages
66 - 67. Answer questions 1 - 6, 8 - 11,
and 13 - 14 (omit questions 7 and 12) from
"Understanding Concepts," "Making
Connections," and "Reflecting" on page
69.
Surface area to volume
• in order to survive, cells must constantly interact
with their surrounding environment.
• Gases and food molecules dissolved in water
must be absorbed and waste products must be
eliminated.
• For most cells, this passage of all materials in
and out of the cell must occur through the
plasma membrane.
• Each internal region of the cell has to be served
by part of the cell surface.
• As a cell grows bigger, its internal volume enlarges and
the cell membrane expands.
• Unfortunately, the volume increases more rapidly than
does the surface area, and so the relative amount of
surface area available to pass materials to a unit volume
of the cell steadily shrinks.
• At some point, there is just enough surface available to
service all the interior; if it is to survive, the cell must stop
growing.
• If the cell grows beyond a certain limit, not enough
material will be able to cross the membrane fast enough
to accommodate the increased cellular volume.