Download Biology Unit 4: Ecology Reference Packet SB4. Investigate the

Biology
Unit 4: Ecology Reference Packet
SB4. Investigate the interdependence of organisms within an ecosystem and the connections between
ecosystems on Earth [symbiosis, competition and parasitism].
a. Investigate the relationships among organisms, populations, communities, ecosystems,
and biomes.
Predation
Predation is another mechanism in which species interact with each other. Predation is when a predator
organism feeds on another living organism or organisms, known as prey. The predator always lowers the
prey’s fitness. It does this by keeping the prey from surviving, reproducing, or both. Predator-prey
relationships are essential to maintaining the balance of organisms in an ecosystem.
True predation is when a predator kills and eats its prey. Some predators of this type, such as jaguars,
kill large prey. They tear it apart and chew it before eating it. Others, like bottlenose dolphins or snakes,
may eat their prey whole. In some cases, the prey dies in the mouth or the digestive system of the
predator. Baleen whales, for example, eat millions of plankton at once. The prey is digested afterward.
True predators may hunt actively for prey, or they may sit and wait for prey to get within striking
distance.
Competition
Competition is a relationship between organisms that strive for the same resources in the same place. The
resources might be food, water, or space. There are two different types of competition:
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Intraspecific competition occurs between members of the same species. For example, two male
birds of the same species might compete for mates in the same area. This type of competition is a
basic factor in natural selection. It leads to the evolution of better adaptations within a species.
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Unit 4: Ecology Reference Packet
Interspecific competition occurs between members of different species. For example, predators
of different species might compete for the same prey.
Interspecific competition often leads to extinction. The species that is less well adapted may get
fewer of the resources that both species need. As a result, members of that species are less likely
to survive, and the species may go extinct.
Instead of extinction, interspecific competition may lead to greater specialization. Specialization
occurs when competing species evolve different adaptations. For example, they may evolve
adaptations that allow them to use different food sources. The Figure below describes an
example.
Symbiosis
Symbiosis is a close relationship between two species in which at least one species benefits. For the other
species, the relationship may be positive, negative, or neutral. There are three basic types of symbiosis:
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Mutualism
Commensalism
Parasitism
Mutualism is a symbiotic relationship in which both species benefit. An example of mutualism involves
goby fish and shrimp
Commensalism is a symbiotic relationship in which one species benefits while the other species is not
affected. One species typically uses the other for a purpose other than food. For example, mites attach
themselves to larger flying insects to get a “free ride.” Hermit crabs use the shells of dead snails for
homes.
Parasitism is a symbiotic relationship in which one species (the parasite) benefits while the other species
(the host) is harmed. Many species of animals are parasites, at least during some stage of their life. Most
species are also hosts to one or more parasites. Some parasites live on the surface of their host. Others live
inside their host. They may enter the host through a break in the skin or in food or water. For example,
roundworms are parasites of mammals, including humans, cats, and dogs.
The worms produce huge numbers of eggs, which are passed in the host’s feces to the environment. Other
individuals may be infected by swallowing the eggs in contaminated food or water. The roundworm
above, found in a puppy's intestine, might eventually fill a dog’s intestine unless it gets medical treatment.
Some parasites kill their host, but most do not. It’s easy to see why. If a parasite kills its host, the parasite
is also likely to die. Instead, parasites usually cause relatively minor damage to their host.
Biology
Unit 4: Ecology Reference Packet
SB4a. Understand the relationship of individual to a population, a community, an ecosystem and a biome.
a. Investigate the relationships among organisms, populations, communities, ecosystems, and
biomes.
Levels of Ecological Organization
Ecosystems can be studied at small levels or at large levels. The levels of organization are described
below from the smallest to the largest:
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A species [individual] is a group of individuals who are genetically related and can breed to
produce fertile young. Individuals are not members of the same species if their members cannot
produce offspring that can also have children. The second word in the two word name given to
every organism is the species name. For example, in Homo sapiens, sapiens is the species name.
A population is a group of organisms belonging to the same species that live in the same area
and interact with one another.
A community is all of the populations of different species that live in the same area and interact
with one another.
An ecosystem includes the living organisms (all the populations) in an area and the non-living
aspects of the environment. An ecosystem is made of the biotic and abiotic factors in an area.
A biome is, in simple terms, is a set of ecosystems sharing similar characteristics with their
abiotic factors adapted to their environments.
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The biosphere is the part of the planet with living organisms. The biosphere includes most of
Earth, including part of the oceans and the atmosphere.
Biology
Unit 4: Ecology Reference Packet
SB4a. Understand the relationship of individual to a population, a community, an ecosystem and a biome.
a. Investigate the relationships among organisms, populations, communities, ecosystems, and
biomes.
b. Explain the flow of matter and energy through ecosystems by
 Arranging components of a food chain according to energy flow.
 Comparing the quantity of energy in the steps of an energy pyramid.
The sun is the source of all the energy in food chains. Green plants, usually the first level of any food
chain, absorb some of the Sun’s light energy to make their own food by photosynthesis. Green plants
(autotrophs) are therefore known as producers in a food chain. Any organism that does not produce
(make) its own food is called a heterotroph or consumer.
Flow of Energy
Yhe levels of a food chain (food pyramid) is called trophic levels. The trophic level of an organism is the
level it holds in a food pyramid.
The sun is the source of all the energy in food chains. Green plants, usually the first level of any food
chain, absorb some of the Sun’s light energy to make their own food by photosynthesis. Green plants
(autotrophs) are therefore known as ‘Producers’ in a food chain.
The second level of the food chains is called the Primary Consumer. These consume the green
plants. Animals in this group are usually herbivores. Examples include insects, sheep, caterpillars and
even cows.
The third in the chain are Secondary Consumers. These usually eat up the primary consumers and
Biology
Unit 4: Ecology Reference Packet
other animal matter. They are commonly called carnivores and examples include lions, snakes and cats.
The fourth level is called Tertiary Consumers. These are animals that eat secondary consumers.
Quaternary Consumers eat tertiary consumers.
At the top of the levels are predators. They are animals that have little or no natural enemies. They are
the ‘bosses’ of their ecosystems. Predators feed on preys. A prey is an animal that predators hunt to kill
and feed on. Predators include owls, snakes, wild cats, crocodiles and sharks. Humans can also be called
predators.
When any organism dies, detrivores (like vultures, worms and crabs) eat them up. The rest are broken
down by decomposers (mostly bacteria and fungi), and the exchange of energy continues. Decomposers
start the cycle again.
Food Chain
Food chains are usually in a sequence, with an arrow used to show the flow of energy.
Producer
Consumer
Consumer
Consumer
Consumer
Autotroph
Herbivore
Carnivore
Carnivore
Carnivore
1st trophic level
2nd trophic level
3rd trophic level
4th trophic level
5th trophic level
100% of the energy
10% of the energy
1% of the energy 0.1% of the energy
0.01% of the energy
Food Web
A food chain is not the same as a food web.
A food web is a network of many food chains and is more complex.
See the food web illustration below—you can pick out a basic food chain from the web:
Green plants
Grasshopper
Frog
Bird
Hawk
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Unit 4: Ecology Reference Packet
SB2.
Students will assess the dependence of all organisms on one another and the flow of energy
and matter within their ecosystems.
c. Relate environmental conditions to successional changes in ecosystems.
Ecological succession is the gradual process by which ecosystems change and develop over time.
Nothing remains the same and habitats are constantly changing.
There are two main types of succession, primary and secondary.
Primary succession is the series of community changes which occur on an entirely new habitat which
has never been colonized before. For example, a newly quarried rock face or sand dunes. The first specie
to inhabit the area is called a pioneer specie.
Secondary succession is the series of community changes which take place on a previously colonized,
but disturbed or damaged habitat. For example, after felling trees in a woodland, land clearance or a fire.
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Unit 4: Ecology Reference Packet
Major Components:
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Succession takes place because through the processes of living, growing and reproducing,
organisms interact with and affect the environment within an area, gradually changing it.
Each species is adapted to thrive and compete best against other species under a very specific
set of environmental conditions. If these conditions change, then the existing species will be
outcompeted by a different set of species which are better adapted to the new conditions.
Ecological niches
An ecological niche encompasses the habits of a species. Essentially it refers to the way a species relates
to, or fits in with, its environment. As a species adapts to the physical parameters and biota within the
community, natural selection favors the development of specialized features that allow the species to
uniquely exploit the surrounding resources.
The niche of a species evolves as physical and biological factors in the community change—provided that
such changes are slow enough to allow species to adapt to them. The main constraint on this evolution
is that no two species in a community can have the same niche.
Biology
Unit 4: Ecology Reference Packet
SB3.
Students will assess the dependence of all organisms on one another and the flow of energy
and matter within their ecosystems.
d. Assess and explain human activities that influence and modify the environment such as global
warming, population growth, pesticide use, and water and power consumption.
The huge increases in size of the human population have resulted in a substantial degradation of
environmental conditions. The changes have largely been characterized by deforestation, unsustainable
harvesting of potentially renewable resources (such as wild animals and plants that are of economic
importance), rapid mining of non-renewable resources (such as metals and fossil fuels), pollution, and
other ecological damages.
At the same time that human populations have been increasing, there has also been a great intensification
of per-capita environmental impacts. This has occurred through the direct and indirect consequences of
increased resource use to sustain individual human beings and their social and technological
infrastructure: meat production, fuel-burning, mining, air and water pollution, destruction of
wild habitat, and so forth.
Fresh Water Loss - According to UN-Water, 75% of planet Earth is covered in water. 97.5% of that is
ocean and 2.5% is freshwater. 70% of freshwater is divided into glaciers and ice caps and the remaining
30% into land surface water, such as rivers, lakes, ponds and groundwater. Most of the freshwater
resources are either unreachable or too polluted, leaving less than 1% of the world's freshwater, or
about 0.003% of all water on Earth, readily accessible for direct human use. According to the Global
Outlook for Water Resources to the Year 2025, it is estimated that by 2025, more than half of the world
population will be facing water-based vulnerability and human demand for water will account for 70% of
all available freshwater.
Species Extinction - Human beings are currently causing the greatest mass extinction of species since the
extinction of the dinosaurs 65 million years ago at rates 1000 to 10,000 times faster than normal. If
present trends continue, scientists warn that within a few decades, at least half of all plant and animal
species on Earth will be extinct, as a result of climate change, habitat loss, pollution, acidifying
oceans, invasive species, over-exploitation of natural resources, overfishing, poaching and human
overpopulation.
Depletion of Natural Resources - As the human population continues to explode, finite natural
resources, such as fossil fuels, fresh water, arable land, coral reefs and frontier forests, continue to
plummet, which is placing competitive stress on the basic life sustaining resources and leading to a
diminished quality of life.
More Intensive Farming Practices – Intensive farming practices produce more and cheaper food per
acre and animal, which has helped feed a booming human population and may prevent surrounding land
from being converted into agricultural land, but has grown to become the biggest threat to the global
environment through the loss of ecosystem services and global warming, has led to the emergence of new
parasites and re-emergence of parasites previously considered to be 'under control' by creating the
conditions for parasite growth and is responsible for 80% of tropical deforestation.
Furthermore, intensive farming kills beneficial insects and plants, degrades and depletes the very soil it
depends on, creates polluted runoff and clogged water systems, increases susceptibility to
flooding, causes the genetic erosion of crops and livestock species around the world, decreases
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Unit 4: Ecology Reference Packet
biodiversity, and destroys natural habitats.
Increased Habitat Loss - Human overpopulation is a major driving force behind the loss of ecosystems,
such as rainforests, coral reefs, wetlands and Arctic ice. Rainforests once covered 14% of the Earth's land
surface, now they cover a bare 6% and experts estimate that the last remaining rainforests could be
consumed in less than 40 years and certainly by the end of the century at the current rate of
deforestation. Due mainly to warming temperatures, acidifying oceans and pollution, close to 30% of the
ocean’s reefs have already vanished since 1980, including half of the reefs in the Caribbean and 90% of
the Philippines’ coral reefs, and scientists forecast that Australia’s Great Barrier Reef may be dead by the
year 2050 and all coral reefs could be gone by the end of the century. Furthermore, the area of permanent
ice cover is now declining at a rate of 11.5% per decade, relative to the 1979 to 2000 average. If this trend
continues, summers in the Arctic could become ice-free in as few as 4 years or in the next 30 years.
Wetlands are increasingly under threat in the United States, but also all over the world. In the U.S., less
than half of original wetlands remain with 53% being lost, which is about 104 million acres
.
Deforestation -the rapid destruction of woodland. Although it can occur due to natural catastrophe it is
most commonly caused by human intervention.
Deforestation has been occurring since humans have been able to cut down trees, but it has increased
greatly over the last century.
The major reasons for deforestation are:
 Obtaining hardwood (e.g., teak) for furniture.
 Obtaining softwood for paper and other wood products.
 Clearing areas for cattle farming.
 Clearing areas for agriculture.
 Clearing areas for urbanization, including road building.
Some effects of deforestation are:
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Changes in nutrient cycles.
Less carbon dioxide is removed from the atmosphere by photosynthesis, leading to a rise in
atmospheric carbon dioxide concentration.
Less oxygen is released into the atmosphere as less photosynthesis occurs.
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Unit 4: Ecology Reference Packet
Fewer trees means less transpiration, which may lead to a less humid atmosphere since less
water evaporates from soil than from leaves.
Increased Global Warming and Climate Change - According to the Center for Biological Diversity,
"The largest single threat to the ecology and biodiversity of the planet in the decades to come will be
global climate disruption due to the buildup of human-generated greenhouse gases in the atmosphere.
People around the world are beginning to address the problem by reducing their carbon footprint through
less consumption and better technology. But unsustainable human population growth can overwhelm
those efforts, leading us to conclude that we not only need smaller footprints, but fewer feet." Every
national academy of science of every major country in the world agrees. Every professional scientific
society in every field related to the field of climate endorses it. 97-98 percent of all scientists that are most
active in publishing in the field of climate science agree with it. The consensus is unequivocal: human
activities are causing climate change. The effects of climate change are profound and far-reaching.
Biology
Unit 4: Ecology Reference Packet
SB4. Students will assess the dependence of all organisms on one another and the flow of energy
and matter within their ecosystems.
e. Relate plant adaptations, including tropisms, to the ability to survive stressful environmental
conditions.
f. Relate animal adaptations, including behaviors, to the ability to survive stressful environmental
conditions.
Most organisms are a combination of many adaptations that allow them to fit into their environment
easily. Adaptations are grouped into three types:
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Structural
Behavioral
Physiological
Tropisms - A tropism is a GROWTH response towards or away from an environmental stimulus coming
from one direction.
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Positive = the plant, or a part of it, grows in the direction from which the stimulus originates.
Negative = growth away from the stimulus.
Forms of tropism include ephototropism (response to light), geotropism (response to
gravity), chemotropism (response to particular substances), hydrotropism (response to water),
thigmotropism (response to mechanical stimulation), traumatotropism (response to wound lesion),
and galvanotropism, or electrotropism (response to electric current). Most tropic movements
are orthotropic; i.e., they are directed toward the source of the stimulus.
Responses of plants
Plants respond to light, gravity, water, chemicals and touch. They do this by a growth curve towards or
away from a stimulus.
If the growth is towards the stimulus we say it is positive; if it is away from the stimulus we say it is
negative.
Animal Responses
Most animal behavior is based on an animal’s desire to survive. The chances of survival are not very good
for an animal that cannot find food or hide from predators. A couple of things have to happen for an
animal to survive.
First, an animal has to sense its environment. Animals sense the environment with body parts called
sensory organs, such as eyes, ears, and noses. We humans have five senses—sight, hearing, smell, taste,
and touch. Other animals use these same senses, but in different ways. Many animals have much better
senses of smell and hearing than humans do. Sensory organs are vital for animals to find food, find mates,
and avoid danger.
Second, an animal has to be able to respond to its environment to survive. Sometimes animals change
their behavior based on experiences they have had in the past. This process of modifying behavior based
on experiences is called learning. No, learning is not all books and memorizing facts—but you knew that
already, right? There are other behaviors that are not learned, but are just ingrained in the animal
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Unit 4: Ecology Reference Packet
throughout its life. This is called innate behavior, which means it does not vary based on experience and
is fixed throughout an animal’s life.
Examples of Behaviors that animals have:
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Hibernation
Migration
Defense
Courtship
Hibernation is a state of greatly reduced body activity, used to conserve food stored in the body.
Animals hibernate because of cold weather.
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Cold Weather (Stimulus)
Hibernation (Response)
Some animals hibernate for part or all of the winter. When hibernation occurs the animals body
temperature drops, the animals heart beat and breathing slow down and the animal uses very little energy
Examples of hibernating animals:
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Ants
Snakes
Black Bears
Beavers
Ground Squirrels
Migration - the movement of animals from one place to another in response to seasonal changes. They
travel to other places where food or space is available.
Defense mechanisms vary with different types of animals. Examples of defense mechanisms are
camouflage, smells, stingers, ejections, mimicry and grouping.
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Camouflage is a protective coloring some animals have to survive
changes in the environment.
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Skunks use an offensive odor in response to fear.
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Wasps and bees use a stinger for protection when frightened or
threatened.
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The black ink cloud of an octopus is a defense mechanism because it gives the animal a
chance to escape from a predator. When the horned lizard gets really scared, it shoots blood
out of its eyes allowing it time to escape.
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Mimicry is when a weaker animal copies a stronger animal’s characteristics to warn off
predators. Examples of this type of animal include a “false” coral snake, hawk moth
caterpillar that looks like a snake, certain moths have markings that look like eyes, certain
flower flies resemble black and yellow wasps that have a powerful sting and use this disguise
to ward off predators.
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Grouping is a social behavior that occurs when certain animals travel together in groups.
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Unit 4: Ecology Reference Packet
Courtship in animals is usually a behavioral process whereby adults of a species try to attract
a potential mate. Courtship behaviors ensure that males and females of the same species
recognize each other. Environmental stimuli, such as seasonal changes, will stimulate
courtship. Often sensory cues will serve as courtship attractants in animals. Examples of these
cues:
 Chemical odor
 Sounds
 Color