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Ecology
• Definition: the study of the relationships between living things and
between living things and their environment.
• Origin of term: From the greek words oikos meaning “house” and
logos meaning “study of”
• Modern Ecological Challenges:
1. Mass extinction: Dramatic increase in the global human
population is leading to 6th mass extinction of species on Earth
and the challenges your generation will have to deal with as a
result.
2. Thinning Ozone Layer: O3 thins over the poles, lets in UV
light. UV light damages DNA.
3. Climatic Changes: Dramatic swings in temperature, shifts in
climate zones (tundra biome moving north), central regions of
Ecology
• Definition: the study of the relationships between living things and
between living things and their environment.
• Origin of term: From the greek words oikos meaning “house” and
logos meaning “study of”
• Modern Ecological Challenges:
1. Mass extinction:
2. Thinning Ozone Layer:
3. Climatic Changes:
Defining an Ecosystem..
•
Ecosystems:
•
Examples:
1. ________
2. __________
3. __________
4. __________
•
The boundaries are usually not clear. Things move from one ecosystem to
another. Pollen can blow from a forest into a field, soil can wash from a
mountain into a lake, and birds migrate from state to state.
•
Ecosystems have resident and transient members.
1. Resident2. Transient-
Open Note Pop Quiz
•
Five basic ecosystem components:
The
Components
of an
Ecosystem
1. Energyeither
chemical energy,
solar
energy, or heat energy
2. mineral nutrients- elements found in the soil and used by organisms
to synthesize large organic molecules (like DNA)
a) Plants: use Nitrogen, Potassium, Phosphorous
b) Animals: get minerals by eating other organisms that ate plants
3. Water- Rivers, Lakes, Streams, Ground water, oceans
4. Oxygen- in atmosphere, dissolved in water
5. Living Organisms- once it is dead it becomes a “nutrient”
•
The sun is the ultimate source of energy that gets passed up the food
chain.
Levels of Ecological Organization
Levels of Ecological
Organization
Biosphere
Ecosystem
Community
Population
Organism
Chapter 5: Section 1
Food Chains
• A food chain is a sequence in which energy is
transferred from one organism to the next as each
organism eats another organism.
• Food chains are linear.
• Virginia Example:
• Wild Strawberry⇒_________⇒ _________⇒ Redtailed Hawk
Chapter 5: Section 1
Food Webs
1. A food web shows many feeding
relationships that are possible in an
ecosystem.
2. A trophic level is one of the steps
in a food chain or food pyramid. All
of the organisms that are the same
distance from a producer are on the
same level.
3. Name 3 organisms that are on the
same level in this diagram:
Trophic Level
Tertiary Consumer
3°
Secondary Consumer
2°
Primary Consumer
(herbivore) 1°
Producers
Mineral Nutrients
Decomposers
Organisms
• Organisms are living things that can carry out life processes
independently.
• Life processes: reproduction, metabolism, growth, homeostasis,
adaptation
• Viruses are not organisms
• Every organism is a member of a species.
• Species are groups of organisms that are closely related can
can mate to produce fertile offspring.
•
“For the good of the species”
– Every individual is still trying to maximize their own fitness
– Fitness: the extent to which an organism can produce fertile
offspring that survive to produce offspring of their own.
Populations
•
Populations are groups of organisms of the same species that live in a
specific geographical area and interbreed. They have access to each
other.
•
For example, all the field mice in a corn field make up a population of
field mice.
•
Fragmentation: When an organisms natural habitat becomes divided
by natural or human-caused disturbance. ie Forest Fire, Clearing land
for development,
•
Another example: Lava flow..
• A non-example: zoo? buried pipeline?
Communities
•
Communities are groups of various
species that live in the same habitat and
interact with each other.
•
Every population is part of at least one
community.
•
The most obvious difference between
communities is the types of species they
have.
•
Terrestrial communities are often
dominated by a few species of plants.
These plants then determine which
organisms can live in that community.
• Oak Forest
• Cypress Swamp
Tidal Pool Community
Communities
Tidal Pool Community
Algae
Coral
Urchin
Chiton
Sea Star
Habitat
• Habitats are places where an organism usually lives.
• Every habitat has specific characteristics that the organisms that
live there need to survive. If any of these factors change, the
habitat changes.
• Organisms usually cannot survive for long periods of time away
from their natural habitat.
• Successful zoos are the ones that most accurately simulate the
organisms natural habitat.
– Ex: nurse shark vs great white
Evolution by Natural
Selection
•
Natural selection is the process by which individuals that have
favorable variations and are better adapted to their environment
survive and reproduce more successfully than less well adapted
individuals do.
• New traits are the product of genetic mutation
• Darwin proposed that over many generations the frequency of a
trait in the population will increase when nature selects over many
generations.
# of individuals expressing a trait
Frequency=
total number of individuals in a population
•
Evolution is a change in the characteristics of a population from one
generation to the next.
Niche
Niche- an organism’s way of life or role it plays in an ecosystem
•
Fundamental Niche- the
range of conditions (temp,
humidity, hours of daylight,
etc.) a species can
potentially tolerate and the
range of resources it can
potentially use (food items,
water)
•
Realized Niche- the range
of resources a species
actually uses.
Nature Selects
Life Depends on the Sun
• Energy from the sun enters an ecosystem when
plants use sunlight to make sugar molecules.
• This happens through a process called
photosynthesis.
Photosynthesis is the process by which plants, algae, and some
bacteria use sunlight, carbon dioxide, and water to produce
carbohydrates and oxygen.
Chapter 5: Section 1
From Producers to Consumers
Because plants make their own food, they are called producers.
• Some producers get their energy directly from the sun by absorbing it
through their leaves as light and heat.
• A producer is an organism that can make organic molecules from inorganic
molecules-- usually through photosynthesis.
• Producers are also called autotrophs, or self-feeders.
Organisms that get their energy by eating other organisms are called consumers.
• A consumer is an organism that eats other organisms or organic matter
instead of producing its own nutrients or obtaining nutrients from inorganic
sources.
• Consumers are also called heterotrophs, or other-feeders.
Chapter 5: Section 1
An Exception to the
Rule
•
Deep-ocean communities of worms, clams, crabs, mussels, and
barnacles, exist in total darkness on the ocean floor, where
photosynthesis cannot occur.
•
The producers in this environment are bacteria that use hydrogen
sulfide present in the water to create organic molecules through
chemosynthesis.
•
Other underwater organisms eat the bacteria or the organisms that
eat the bacteria.
Chapter 5: Section 1
What Eats What?
•
Organisms can be classified by what they eat.
•
Types of Consumers:
• Herbivores
• Carnivores
• Omnivores
• Decomposers
Chapter 5: Section 1
Burning the Fuel
•
All heterotrophic organisms obtain energy from the food it eats.
•
This food must be broken down within its body to release energy.
• Part of the energy is used to carry out daily activities.
• Excess energy is stored as fat (animals) or sugar (plants).
•
The process of breaking down food to yield energy is called cellular
respiration.
• Cellular Respiration is the process by which cells produce energy from
carbohydrates; atmospheric oxygen combines with glucose to form water
and carbon dioxide.
• Cellular respiration occurs inside the cells of most organisms.
• Cell Respiration Equation:
Chapter 5: Section 1
Energy Transfer
•
Each time an organism eats another organism, an energy transfer
occurs.
•
This transfer of energy can be traced by studying food chains, food
webs, and trophic levels.
•
Each time energy is transferred by organism eating organisms from a
lower trophic level, most of the energy is lost as heat and waste.
•
Therefore, less energy is available to organisms at higher trophic
levels.
•
One way to visualize this is with an energy pyramid.
Chapter 5: Section 1
What does this suggest about the area
(square meters..etc) needed by each
organism?
Chapter 5: Section 1
Trophic Levels
•
Each layer of an energy pyramid represents one trophic level.
•
Producers form the base of the energy pyramid, and therefore
contain the most energy.
•
The pyramid becomes smaller toward the top, where less
energy is available. The volume of each layer of the pyramid
= the energy that has been passed up from the trophic level
beneath it.
Chapter 5: Section 1
Energy Loss Affects Ecosystems
•
Decreasing amounts of energy at each trophic level affects the
organization of an ecosystem.
1.
Energy loss affects the number of organisms at each level.
2.
Energy loss limits the number of trophic levels.
3.
Due to the limited amount of energy at each level, the number of
3° or 4° consumer species in any one ecosystem is small
compared to the number of primary consumers.
Chapter 5: Section 2
The Carbon
Cycle
The Carbon
Cycle
Chapter 5: Section 2
1. The carbon cycle is the movement of carbon from the nonliving
environment into living things and back
2. Carbon is the essential component of proteins, fats, and
carbohydrates, which make up all organisms
3. Increased levels of carbon dioxide may contribute to global
warming.
4. Carbon moves through the atmosphere, hydrosphere,
geosphere and biosphere:
•
Producers convert carbon dioxide in the atmosphere into
carbohydrates during photosynthesis.
•
Consumers obtain carbon from the carbohydrates in the
producers they eat.
Chapter 5: Section 3
Ecological Succession
Year 1:
annual
plants
Year 2:
Year 3-10
About 20 Years:
perennial shrubs, shade- young forest, shadeplants and
intolerant
tolerant seedling
grasses
plants
appear
After about 150 years:
Climax community
•
Ecological succession is a gradual process of change and
replacement of the types of species in a community.
•
Each new community that arises often makes it harder for the previous
community to survive.
Ecological Succession
•
Primary succession is a type of succession that occurs on a
surface where no ecosystem existed before. It begins in an area that
previously did not support life.
1. Primary succession can occur on rocks, cliffs, or sand dunes. A
pioneer species is a species that first colonizes an uninhabited
area. Over time, a pioneer species will make the new area habitable
for other species.
2. A climax community is the final, stable community in equilibrium
with the environment.
3. Even though a climax community may change in small ways, this
type of community may remain the same through time if it is not
disturbed.
Chapter 5: Section 3
Ecological Succession
•
Natural fires caused by lightning are a necessary part of secondary
succession in some communities.
• Minor forest fires remove accumulations of brush and deadwood that
would otherwise contribute to major fires that burn out of control.
• Some animal species also depend on occasional fires because they
feed on the vegetation that sprouts after a fire has cleared the land.
• Old-field succession is a type of secondary succession that occurs
when farmland is abandoned.
•
When a farmer stops cultivating a field, grasses and weeds
quickly grow and cover the abandoned land.
•
Over time, taller plants, such as perennial grasses, shrubs, and
trees take over the area.
Chapter 5: Section 3
Ecological Succession
Ecological Succession
• Primary succession can occur
1. on new islands created by
volcanic eruptions
2. in areas exposed when a
glacier retreats
3. any other surface that has not
previously supported life
1
2
• Primary succession is much
slower than secondary
succession. This is because it
begins where there is no soil.
3
Chapter 5: Section 3
Ecological
Succession
•
The first pioneer species to colonize bare rock will probably
be bacteria and lichens, which can live without soil.
•
The growth of lichens breaks down the rock, which with the
action of water, begins to form soil.