Ecology Review
Ecology Review
Ecology is a branch of biology that deals with the relationships between organisms (living things) and
their surroundings.
An ECOSYSTEM is all of the living organisms (biotic factors) that live together with the nonliving
factors (abiotic factors) of an environment.
*Remember......... Biotic be living
Abiotic a'int be living
Species- specific kind of organism
Population- a group of organisms of the SAME species. For example.: All the deer in the forest or all
of the catfish in the pond
Community- all of the LIVING things in an ecosystem
Organisms make up species> all of one species make up a population> all of the populations in an
area make up a community> the community of living things along with all of the abiotic factors in an
area make up an ecosystem :)
LIMITING FACTORS AND COMPETETION:
An ecosystem can only hold a certain number of organisms. LIMITING FACTORS are things that limit
how many organisms can live in an environment. Limiting factors can be biotic like the amount of food
available or abitoic such as light, water, range of temperature, and soil composition.
Because there is a limited amount of resources in an environment organisms must compete for those
resources.
INTRAspecific competition- competition between organisms of the SAME species
INTERspecific competition- competition between organisms of DIFFERENT species
Every organism has a role in their habitat (where they live) and we call this their NICHE. Because of
this the more BIODIVERSITY (different kinds of living things) in an environment the more likely the
environment will do well. Remember the definition of biodiversity by remembering BIO means life and
DIVERSITY means different....so biodiversity means different kinds of living things. More
biodiversity = GOOD :)
SYMBIOSIS:
When organisms interact closely with each other in their environment we call this SYMBIOSIS. There
are 3 types of symbiosis:
1. MUTUALISM- You have probably heard the saying "the feeling is mutual" that means we both feel
the same way. Mutualism is where both organisms BENEFIT from the relationship with each other.
Example- ants defend the acacia tree, the tree feeds the ants.
2. COMMENSALISM- One organisms benefits and the other isn't helped or harmed. ExampleCow birds eat the insects that fly up when cows walk on the grass. The birds are helped but the cows
are not helped or harmed.
3. PARASITISM- When one organism benefits and the other is harmed. Example- a tick on a dog.
The tick feeds on the dog and the dog is harmed. The tick would be the parasite and the dog would
be the host (the organisms that is harmed)
ENERGY IN ECOSYSTEMS
Energy in an ecosystem ALWAYS begins with RADIANT ENERGY FROM THE SUN. Remember
that even though the sun is usually not drawn as part of a food pyramid.
Food Chain- a diagram that shows one possible feeding relationship.
Example: Grass > grasshopper > bird > snake
Food Web- a series of interconnected food chains. Example:
If
any organism in the food web is affected then it affects all of the other organisms in the web. For
example, if mice were killed off in the food web above then there would be more corn so there would
be more rats. More rats would mean more hawks could survive because there would be more food.
Having less mice could decrease the number of snakes that eat them., etc...
Energy Pyramid- a graphical representation of trophic levels (feeding levels) that shows how
energy from the sun is transferred throughout the ecosystem. The pyramid is largest at the bottom
because that's where there is the most organisms and the most energy. The bottom of the pyramid is
always made up of producers (plants) and there are more plants than there are consumers in the
ecosystem. As you move up the pyramid gets smaller showing that there are fewer organisms at
each level and less and less energy available. Only 10% of energy is passed on from one level to the
next !!
Let's review some ecosystems vocabulary!!
Producer- Also known as a plant or an autotroph ("auto" means self and "troph" means feed.
Autotrophs are self feeders). They make their food through photosynthesis :)
Consumer- has to eat its food to get energy. There are several types of consumers:
Primary Consumer- Eat producers/plants. Primary consumers are also called herbivores (only eat
plants)
Secondary Consumer- Eat primary consumers. Sometimes omnivores (eat plants and animals)
Tertiary Consumer- Eat secondary consumers. Usually carnivores (only eat other animals/meat
eaters)
*Remember- Primary means one, secondary means 2, and tertiary means 3. Each level of consumer eats the level
beneath it*
Scavengers- Eat the leftovers of dead or decaying animals. Example- vultures, hyenas
Decomposers- Break down and recycle the nutrients from the remains or wastes of other organisms.
Example- bacteria and fungi
Native Species- Native means natural to that area. A native species is a plant or animal that lives in
a certain area due to natural causes. For example, the bluebonnet is native to Texas.
Alien Species- This is talking about an organism that is not natural to an area....it has been brought
in by humans. For example, the South American fire ant was brought to Alabama in 1940 and has
since spread all around the southern United States.
Invasive Species- Just like the name says this is a species native or alien that has come in and
taken over or invaded and area. It could be a plant or an animal. For example, the Asian Carp is a
fish that has come in from Asia and completely taken over US rivers to the point that they are killing
off all of the native species by eating all of the available food.
Human Impact on the environment:
ž Extinction is a natural process, but some species’ extinction is related to the activities of
humans.
ž Many factors affect extinction: habitat loss, pollution, and overhunting/ overfishing.
ž Endangered species are in danger of becoming extinct.
ž Threatened species are in danger of becoming endangered.
RUNOFF
•Runoff is the excess water that carries pollutants into storm drains and then to the ocean.
•It is an environmental problem for all communities. Residents who live miles inland can contribute
to ocean pollution simply by leaving their sprinklers on too long, washing cars at home, or hosing
down driveways.
•After this wasted water flows to the curb it carries trash, fertilizers, pet waste and other
pollutants into the storm drain system which eventually flows into the ocean.
ž -Sediment can cloud the water and make it difficult for aquatic plants to grow and can destroy
aquatic habitats.
ž -Excess nutrients can cause algae blooms. When they die, they decompose in a process that robs
the water of its oxygen. Fish can’t live in areas with low oxygen levels.
-ž Bacteria can wash into swimming areas, making beach closures necessary.
-ž Debris such as plastic bags, six-pack bottle rings, and cigarette butts can wash into water bodies
and choke, suffocate, or disable ducks, fish, turtles, and birds.
ž Household hazardous wastes like insecticides, pesticides, paint, solvents, and used motor oil can
poison aquatic life.
ARTIFICIAL REEF
It is a human-made underwater structure built for the purpose of promoting marine life. Artificial reefs
can have positive effects or negative effects. ž They are build by: sinking oil rigs, scuttling ships,
construction debris, PVC or concrete, as well as historic or modern shipwrecks.
ž
OVER FISHING
Continually catching more fish than the ocean can naturally produce creating ecological dead zones
in the oceans and taking a away a major food source for the majority of the world.
DEFORESTATION
As humans expand into areas where plants and animals live, habitats are lost. We build roads,
houses, so animals must leave. ž Cutting down trees for wood destroys habitats of birds and other
animals that live in trees.
STOP here and wait to read this once you have finished the
rest of your lab assignments :)
Some Key Concepts for you to take a look at.......
Key Concepts
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Key Concept 1: Energy flows through various food chains as animals eat plants and predators consume prey,
creating a food web. The energy that flows though food chains and food webs comes from the Sun.
Key Concept 2: Trophic levels of organisms in a food web range from primary producers (autotrophs), and
different levels of heterotrophs, including primary consumers (herbivores), secondary consumers (carnivores that
eat herbivores), and tertiary consumers (carnivores that eat carnivores).
Key Concept 3: Other relationships in an ecosystem include predator/prey relationships and parasite/host
relationships.
Key Concept 4: Aquatic ecosystems include freshwater and marine biomes and constitute the largest part of the
biosphere. In marine ecosystems, phytoplankton are autotrophic producers and are consumed by zooplankton
and small invertebrates, which are consumed secondarily by fish and larger marine life.
Key Concept 5: In terrestrial ecosystems, the primary producers are plants, which are consumed by insects,
arthropods, and grazing animals. Secondary consumers include spiders, frogs, and carnivorous animals.
Key Concepts
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Key Concept 1: Resources for an organism’s habitat, including space, food, shelter, and water, may be limited or
depleted by competition. Two species cannot operate in the same niche in the same environment.
Key Concept 2: Organisms rely on natural resources in their environment such as quantity of light, water supply,
and suitable temperature.
Key Concept 3: Competition occurs when niches overlap and organisms seek the same resources, especially
when the population density is high.
Where a species lives and how well it prospers depends on many abiotic and biotic factors. Organisms depend on the
non-living, natural resources in their environments, or abiotic factors, in order to live. Abiotic factors include anything in the
organism’s environment that may affect its survival and growth, such as the sunlight, temperature, shelter, or water
supply. Temperature is one of the most important abiotic factors that influences organisms. If an organism is sensitive to
changes in temperature, for example, such as plants that cannot tolerate frost, then it is less likely to survive outside of the
tropics. Biotic factors are anything related to living organisms that would impact another organism. Competition for
resources and predator-prey relationships are biotic factors. For example, one biotic factor for a field mouse is another
animal competing with it for food, or a hawk that is hunting the field mouse.
An organism’s niche is the role it plays in the ecosystem. A niche includes anything that affects the organism or that it
affects, such as its environment (abiotic factors) or its predators and prey (biotic factors). An organism survives, grows,
and successfully reproduces, if it is well suited for its niche. In other words, there is no other organism that uses the same
abiotic or biotic factors. Competition occurs when organisms begin to overlap their niches with other organisms that live in
the same place and want the same resources.
If an area provides a limited amount of resources, then different organisms are going to compete with each other over
resources for survival. There are primarily two different kinds of competition. Intraspecific competition is when members of
the same species compete for the same resources. For example, two field mice compete for the same food source. This
type of competition is more likely to happen when the species is at a high population density, has limited supplies of
resources available, or experiences a combination of those two conditions. When different species compete, it is called
interspecific competition. For example, different plants compete with each other for light in order to grow. If one plant can
grow taller (an oak tree), it can get the resource it needs (light), while shorter plants (a shrub) cannot. This is why forests
with a tightly closed canopy often lack shrubs growing on the forest floor beneath. Other, more finite, resources, such as
food, shelter, or water, can become limited or depleted when there are too many organisms competing for them. This can
lead to population declines. For instance, if lions and hyenas compete for the same food source, such as zebras, then
theharvesting by these predators can reduce the zebra population. Population reduction means fewer food resources for
all of the lions and hyenas, whichleads to a decline in these predator populations. However, just because organisms
compete for the same resources or with each other, does not always mean that one organism always has to win and the
other dies out or becomes extinct. Organisms that compete with each other can coexist if they share resources. Such
coexistence may simply mean that their population sizes remain relatively small.
Key Concepts
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Key Concept 1: Changes in environmental conditions can affect the survival of individual organisms and entire
species.
Key Concept 2: Long-term environmental changes, like climate change, can permanently alter an ecosystem, but
over time the change may cause some genetic variations to become more favorable or less favorable in the new
environment. If adaptations to the new environment are not present or do not develop, populations can become
extinct.
Key Concept 3: Short-term environmental changes, like floods, don’t give populations time to adapt to change
and force them to move or become extinct.
Key Concept 4: Human activity affects natural systems through agriculture, resource consumption, and pollution
from waste disposal and energy production.
Key Concepts
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Key Concepts 1: Oceans are Earth’s largest ecosystem. Ocean systems circulate energy, and ocean
temperatures regulate Earth’s climate and weather.
Key Concept 2: Marine algae produce oxygen, consume atmospheric carbon, and play an important role in the
cycling of matter for life on Earth.
Key Concept 3: Human activity such as runoff pollution can originate from small or large sources on land and
water, including motorized vehicles, oil spills, agricultural chemicals, and recreation. Runoff pollution negatively
affects beaches and ocean habitats.
Key Concept 4: Overharvesting food from the ocean creates an imbalance in existing ocean food webs. Other
examples of the effects of human activity on oceans include climate change, spread of disease, and introduction
of exotic species.