Ecology Notes

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Ecology Notes

• The chapters in your book are being used in
  combination, you need to pay close attention to
  detail in class or you will get behind. Reading
  the chapters on ecology is expected of you!

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OUTLINE

• I. Organisms in their Environment
• A. Aspects of Ecological Study
• 1. Ecology is the scientific study of
  interactions among organisms and their
  environments.
• a. Ecological study reveals relationships
  among living and nonliving parts of the world.
• b. Ecology combines information and techniques
  from many scientific fields including
  mathematics, chemistry, physics, geology, and
  other branches of biology.
• 2. The biosphere is the portion of Earth that
  supports life.
• a. The biosphere is very diverse and supports
  a wide range of organisms.
• b. It extends from high in the atmosphere to
  the bottom of the oceans.

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• B. Nonliving Environment
• 1. Ecology includes the study of features of
  the environment that are not living because these
  features are an important part of an organisms
  life.
• 2. The nonliving parts of an environment are
  the abiotic factors.
• 3. Some examples of abiotic factors are air
  currents, temperature, moisture, light and soil.
• C. Living Environment
• 1. All the living organisms that inhabit an
  environment are called biotic factors.
• 2. To help them understand the interactions of
  the biotic and abiotic parts of the world,
  ecologists have organized the living world into
  levels.

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• D. Levels of Organization in Ecology
• 1. All organisms depend on others for food,
  shelter, reproduction, or protection.
• 2. Ecologists study interactions among
  organisms at several different levels.
• a. They study individual organisms,
  interactions among organisms of t he same
  species, and interactions among organisms of
  different species.
• BIOSPHERE BIOMES ECOSYSTEMS
  
• COMMUNITIES POPULATIONS

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• E. Interactions within populations
• 1. A population is a group of organisms of one
  species that interbreed and live in the same
  place at the same time.
• 2. Members of the same population may compete
  with each other for food, water, or other
  resources.
• 3. Competition only occurs if resources are in
  short supply.
• 4. Some species have adaptations that reduce
  competition within a population.
• F. Individuals interact within Communities
• 1. No species lives independently of other
  species.
• 2. A community is made up of several
  populations interacting with each other.

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• G. Interactions among living things and abiotic
  factors form Ecosystems
• 1. In addition to population interactions,
  ecologists also study interactions among
  populations and their physical surroundings in
  ecosystems.
• 2. An ecosystem is made up of the interactions
  among the populations in a community and the
  communitys physical surrounding, or abiotic
  factors.
• 3. There are three major kinds of ecosystems
• a. Terrestrial Ecosystems are those located on
  land.
• b. Fresh Water (Aquatic) Ecosystems are bodies
  of fresh water.
• c. Salt Water (Aquatic) Ecosystems are bodies
  of salt water.

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• H. Organisms in Ecosystems
• 1. A habitat is the place where an organism
  lives out its life.
• 2. Habitats can change, and even disappear,
  from an area.
• 3. Each species is unique in satisfying all its
  needs each species occupies a niche.
• a. A niche is the role and position a species
  has in its environment- how it meets its needs
  for food and shelter, how it survives, and how it
  reproduces.
• b. A species niche includes all its
  interactions with the biotic and abiotic parts of
  its habitat.
• 4. Biologists once assumed that all organisms
  living in the same environment are in a
  continuous battle for survival.

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• 5. Some interactions are harmful to one species,
  yet beneficial to another.
• 6. Predators are animals such as lions and
  insect-eating birds that kill and eat other
  animals.
• a. The animals that predators eat are called
  prey.
• b. Predator-Prey relationships involve a fight
  for survival.
• 7. The relationship in which there is a close
  and permanent association among organisms of
  different species is called symbiosis.
• a. Commensalism is a symbiotic relationship in
  which one species benefits and the other species
  is neither harmed nor benefited.
• 1. Spanish moss grows on and hangs from the
  limbs of trees but does not obtain any nutrients
  or cause any harm to the trees.

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• b. Mutualism is a symbiotic relationship in which
  both species benefit from the relationship.
• 1. Ants and Acacia Trees
• c. Parasitism is a symbiotic relationship in
  which one species thrives at the expense of the
  other species (predator usually causes harm in
  this situation but not death).
• 1. Ticks sucking nutrients from animals.
• II. Nutrition and Energy Flow
• A. How Organisms obtain Energy
• 1. One of the most important characteristics of
  a species niche is how the species obtain its
  energy.
• 2. The ultimate source of the energy is the
  sun, which supplies the energy that fuels life.

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• 3. The producers Autotrophs
• a. Organisms that use energy from the sun or
  energy stored in chemical compounds to
  manufacture their own nutrients are called
  autotrophs.
• b. Most other organisms depend on autotrophs
  for nutrients and energy.
• 4. The consumers Heterotrophs
• a. Organisms that cannot make their own food
  and must feed on other organisms are called
  heterotrophs.
• b. Heterotrophs include organisms that feed
  only on autotrophs, organisms that feed only on
  other heterotrophs, and organisms that feed on
  both autotrophs and heterotrophs.
• c. A heterotroph that feeds only on plants is
  called a herbivore.
• d. Some heterotrophs eat other heterotrophs
  and are called carnivores.
• e. Animals that eat animals that have already
  dies are called scavengers.
• f. Humans are an example of a third type of
  heterotroph called omnivores-eating both animals
  and plants.
• g. Some organisms break down and absorb
  nutrients from dead organisms and are called
  decomposers.
• h. Decomposers break down the complex
  compounds of dead and decaying plants and animals
  into simpler molecules that can be more easily
  absorbed by the decomposers, and by other
  organisms.

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• B. Matter and Energy Flow in Ecosystems
• 1. Matter and energy flow through organisms in
  ecosystems.
• 2. Ecologists make models that trace the flow
  of matter and energy through ecosystems.
• 3. Food chains Pathways for matter and energy
• a. A food chain is a simple model that
  scientists use to show how matter and energy move
  through an ecosystem.
• b. A food chain is typically drawn using
  arrows to indicate the direction in which energy
  is transferred from one organism to the next.
• 1. Food chains can consist of three links, or
  steps, but most have no more than five links.
• 2. This is because the amount of energy
  remaining in the fifth link is only a small
  portion of what was available at the first link
  energy is lost at each link as heat.

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• 4. Trophic levels represent links in the chain
• a. Each organism in a food chain represents a
  feeding step, or trophic level, in the passage of
  energy and materials.
• b. A food chain represents only one possible
  route for the transfer of matter and energy in an
  ecosystem.
• c. In addition, many different kinds of
  organisms eat a variety of foods, so a single
  species may feed at several trophic levels.
• 5. Food Webs
• a. The model that ecologists create expresses
  all the possible feeding relationships at each
  trophic level in a community is called a food
  web.
• b. A food web is a more realistic model than a
  food chain because most organisms depend on more
  than one other species for food.

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• 6. Energy and trophic levels Ecological
  Pyramids
• a. Ecologists use food chains and food webs to
  model the distribution of matter and energy
  within an ecosystem.
• b. An ecological pyramid shows how energy
  flows through an ecosystem.
• 1. The base of the ecological pyramid
  represents autotrophs.
• 2. Higher trophic levels are layered on top
  of another.
• c. Observe that each pyramid summarizes
  interactions of matter and energy at each trophic
  level.

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• d. The total energy transfer from one trophic
  level to the next is only about ten percent
  because organisms fail to capture and eat all the
  food available at the trophic level below.
• e. The energy lost at each successive trophic
  level enters the environment as heat.
• 1. Ecologists construct a pyramid of numbers
  based on the population sizes of organisms in
  each trophic level.
• 2. A pyramid of biomass expresses the weight
  of living material at each trophic level.
• 3. Ecologists calculate the biomass at each
  trophic level by finding the average weight of
  each species at the trophic level and multiplying
  by the estimated number organisms in each
  population.

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• Food chains, food webs, and ecological pyramids
  all show how energy moves in only one direction
  through the trophic levels of an ecosystem.
  Ecological pyramids also show how energy is lost
  from one trophic level to the next. This energy
  is lost to the environment as heat generated by
  the body processes of organisms. Sunlight is the
  primary source of all this energy so energy is
  always being replenished.
• C. Cycles in Nature
• 1. Matter, in the form of nutrients, moves
  through the organisms at each trophic level, but
  matter cannot be replenished like the energy from
  sunlight.
• 2. Matter is constantly recycled.

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3. In the water cycle, water is constantly moving
between the atmosphere and Earth.
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4. From proteins to sugars, carbon is the
building block of the molecules of life. Linked
carbon atoms form the frame for molecules
produced by plants and other living things.
Organisms use these carbon molecules for growth
and energy.
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5. In the nitrogen cycle, nitrogen is converted
from a gas to compounds important for life and
back to a gas.
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6. In the phosphorus cycle, phosphorus moves
between the living an non-living parts of the
environment.