introduction our past ancestors stood on the face of this earth with the belief that it was a...
TRANSCRIPT
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• The old paradigms have been replaced by new paradigms.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
• Space
• Temperature
• Oxygen
• Sunlight
• Water
• Inorganic and organic soil nutrients
Biotic Factors
• 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
– 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 plants3. Secondary consumers –feed on primary consumers4. Tertiary consumers – top consumer because it is at top of food chain5. 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 JMouse – primary consumer - 1 000 JSnake – secondary consumer - 100 JHawk – 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)
Corn
Mouse
Snake
Hawk
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.