One of the major themes of life is Interdependence, which states that organisms are dependent on one another & their env’t

ECOLOGY – The study of the interactions of living organisms w/ one another and w/ their env’t

I. Introduction A. Groups of Organisms1. Population – group of organisms of the

same species living in a particular place at a particular time.

a. Species: a group of organisms that look alike, are genetically similar, & can reproduce

b. In biology, these organisms will interbreed & mate w/in the population

c. Examples:

2. Community – Different populations that live in the same area & interact with one another

--Example: Marine community

3. Biome/Ecosystem – Communities of living things interacting with each other AND with their physical env’t.-- Example: Tropical Rainforest, Desert, Savannah, Tundra

4. Biosphere – All the life supportive env’ts andorganisms on this planet.

B. Three important characteristics of every population:

1. geographic distribution (i.e. the area being inhabited)

2. size & density (# of organisms in an area and how are they dispersed)

3. growth rate (i.e. do they grow, stay the same, or decrease in size) growth: 1. when birth > death 2. immigration – move into pop. decrease: 1. when birth < death

2. emigration – move out of pop.

C. Organisms in a Population are Dispersed Dispersion – How individuals w/in Pop. are arranged

1. Clumped – Individuals are bunched together into clusters

2. Even/Uniform – Individuals are located at regular intervals

3. Random – location is self-determined

II. Predicting population growth Considers Carrying Capacity – The Pop. size that an env’t can sustain. Affected by predators, prey, resources, etc.

Pop. < carrying capacity = rapid growth

Pop. reaches carrying capacity = growth

stops (death rate = birth rate)

Two basic types of growth…

a. Exponential growth curve- unlimited resources

- predators are few or non-existent

b. Logistic model- declining resources

(i.e. competition)- increases in # of predators

Limits to Growth within a Population

Limiting resources – growth depends on those resources needed for survival (ex. food, water, shelter)

Limiting Factors – factors that cause population growth to stop by depleting limiting resources (ex. Disease, hunting, natural disaster, deforestation, climate)

III. Types of Populations

A.r-strategists – Exhibit exponential growth when conditions allow (Ex: cockroaches, fruit flies)

B.K-strategists – Population is usually near the carrying capacity (Ex: whales, humans)

IV. Population Genetics: How Populations Evolve There are a variety of factors that affect how a population evolves (Hardy-Wein.):1. Mutations – Very slow, affects are seen over long period of time (source of variations)

Ex: cancer, bacteria strains

2. Gene Flow – Migration, mov’t in/out of Pop.3. Non-random Mating (selection): inbreeding

4. Genetic Drift – certain genes only found in 1 or 2 indiv. (small Pop. affected most)

5. Natural selection – “survival of the fittest” -- strongest individuals will pass on traits

COMMUNITIESWhat is Community Ecology?

The study of how populations of organisms (living in a small area) interact with each other

I. Characteristics of Communities

A. Community Interactions Populations of organisms often interact w/ each other in complex ways.1. Predator-Prey Interaction - Predation – one organism (predator) captures & feeds on another (prey)

2. Competition – when organisms compete with each other for resources (food/shelter)

3. Symbiosis – any relationship in which two organisms live closely together. Four types:

a. mutualism - when both organisms benefit

b. commensalism - when one benefits and theother is unaffected

c. amensalism - when one is harmed & the the other is unaffected

d. parasitism - when one benefits & the otheris harmed

BENEFIT HARM NO

EFFECT

BENEFIT

HARM

NO EFFECT

effects on organism 1

effects on organism 2

commensalism

competitionamensalism

mutualism predation/parasitism

commensalism

predation/parasitism

amensalism xxxxxxxxxxx

B. The Ecological Niche

1. The ecological position of a species in a community. The “role” it plays in the community & larger ecosystem (ex. An animals place in the food web)

2. Includes the physical and biological conditions needed to survive. (ex. food source, temp, live near water…)

Ecosystems(a.k.a. Biomes)

A “Community” of living things together WITH the physical env’t.

(how populations interact with each other AND their environment)

I. What is an Ecosystem?

The living organisms are known as biotic factors

The physical (i.e. non-living) aspects are

called abiotic factors (e.g. water, soil, climate, temp.)

Together, these factors determine the survival, growth & productivity of organisms & the ecosystem

Organisms create a habitat within an ecosystem

II. Energy Flow All living things require energy for metabolism and growth The flow of NRG determines what kind & how many organisms an ecosystem can support

A. Producers (a.k.a. Autotrophs)

1. The primary source of NRG is the sun 2. All life depends on organisms that can

capture solar NRG and convert it to chemical NRG

(i.e. glucose) during photosynthesis 3. Thus, they produce their own NRG and

food for other organisms

B. Consumers (a.k.a. Heterotrophs) organisms that must rely on other organisms

for food and NRG

PHOTOSYNTHESIS

Sun + 6CO2 + 6H2O C6H12O6 + 6O2

C. Trophic Levels

1. a group of organisms that obtain their NRG

from a common source 2. NRG moves from one level to another

3. There are five levels…

1. Lowest level: Primary producers (a.k.a. photosynthesizers)

Plants

Algae

Some bacteria

2. Level two: Primary consumers Eat the primary consumers

known as Herbivores

Caterpillars

Cows

Grasshoppers Geese

Mice

3. Level three: Secondary consumers Eat the primary consumers

known as Carnivores – eat the herbivores

4. Level Four: Tertiary consumers a. Top carnivores – eat all other animals

b. Omnivores – eat plants & animals

5. Level Five: Detritivores (a.k.a. decomposers)

- a class of consumers that obtain their NRG from the organic wastes & dead bodies produced at all trophic levels.

Worms FungiBacteria

Decomposers: worms, fungi, bacteria help to recycle nutrients and elements

II. Energy Flow Through an Ecosystem Exploring Feeding Relationships

A. Food Webs a. interconnected network of food chains that traces the directional flow of NRG in an eco.

b. animals feed at several levels, thus NRG doesn’t flow in straight paths.

Food Web

B. Ecological Pyramids

1. Diagrams that show the relative amounts of NRG and matter contained within each trophic level.

2. Three types of pyramids:

ENERGY PYRAMIDS

1. organisms use NRG to metabolize, thus, much of their NRG is lost as heat

during biochemical reactions (can’t be used)2. 10% RULE: only 10% of the NRG available at one trophic level is transferred to organisms at the next level.

Energy Loss

Biomass Pyramid (total amount of living tissue at each level)

Pyramid of Numbers(shows the number of individual organisms at each troiphic level)

III. Ecosystem Cycles in addition to NRG, organisms need

other inorganic substances to fxn Although NRG flows in one direction;

carbon & other inorganic substances are constantly recycle

Biochemical cycle – substances pass from nonliving env’t (e.g. soil, atmosphere) to living things, & back to nonliving env’t

Four critical substances needed to sustain health of an ecosystem: C, N, P, H2O

A. The Water Cycle1. Water vapor condenses and falls as precipitation2. Some seeps into soil and becomes ground water (below

surface)3. Most runs-off surface back to oceans & lakes4 Sun heats oceans & lakes and water evaporates back into

the atmosphere (transpiration – the evaporation of water from

plants)

B. The Carbon Cycle * carbon forms the backbone of all organisms

1. How is CO2 taken out of atmosphere? Photosynthesis CO2 is used by plants & algae to build GLUCOSE Consumers will get their carbon by eating other organisms or their remains

2. How is C returned to the atmosphere as CO2?

a. Cellular Respiration by organisms: 6O2 + C6H12O6 6CO2 + 6H2O

b. Combustion -- dead organisms decompose and form oil &

coal (i.e. fossil fuels) underground…humans

BURN -- humans also cut down and burn forests

c. Volcanic activity

The Carbon Cycle

C. The Nitrogen Cycle * 78% of atmosphere is N2, but also in DNA, RNA, proteins1. Though abundant, it can’t be used as a gas from

the air. Needs to be converted into a usable form (i.e. ammonia, NH3), in a process called, nitrogen fixation

done by bacteria in roots of plants and in soil2. When organisms decompose, nitrogen is also put into the soil as ammonia, which can be used by producers3. Nitrification – ammonia is converted into nitrates (NO3

-) by different bacteria in soil4. Denitrification – nitrates are converted back into nitrogen gas which is released back into atmosphere

The Nitrogen Cycle

D. The Phosphorus Cycle (for DNA/RNA) * different b/c atmosphere doesn’t play a role

1. On Land: Phophorus exists primarily as phosphate

(PO43-)

found in soil deposits, which can be absorbed by

plants & then eaten by consumers Consumers decompose & release phosphate

back into ground to be taken up by producers

2. In Ocean Phosphate also found in ocean sediment. When erosion from land occurs or these sediments break down, phosphate released into ocean & dissolved. Then taken up by algae, eaten by consumers, and excreted back into ocean

The Phosphorous Cycle

IV. Nutrient Limitations The 4 cycles are imported b/c they provide ecosystem w/ nutrients

Primary productivity – the rate at which producers use these nutrients to create organic matter.

Short supply of any nutrient will slow growth and p productivity (why farmers use fertilizers)

Aquatic systems may get too much nutrient leading to build up of algae, known as an algal bloom, which can be bad if not enough consumer to keep in equilibrium

Human Impact on the BIOSPHERE

1. Acid Rain – The acidified precipitation that results when sulfur-rich smoke combines w/ water vapor to produce sulfuric acid The smoke is a result of power plants burning fossil fuels (coal & oil), as well as car exhaust

2. Ozone Depletion

a. Ozone (O3) – the layer of the atmosphere that protects living organisms from harmful UV light

b. Ozone depletion results from CFC breakdown

1. CFC’s (ChloroFluoroCarbons) – molecules containing chlorine, fluorine, and carbon

2. Sources:

Coolant systems Aerosols Foaming Agents

3. When CFC’s are released into the atmosphere, UV radiation breaks the bonds, thus releasing chlorine atoms which break down ozone

3. Global Warming The Greenhouse Effect – The warming of the atmosphere due to greenhouse gases (CO2, methane, nitrous oxide)

Short wave solar NRG pass thru atmosphere and hits earth Some is absorbed; some is reflected back into the atmosphere as long wave radiation This radiation can’t pass thru clouds or CO2

It is absorbed or reradiated back to earth Thus, earth is heated

This is similar to a “greenhouse”

a. The greenhouse effect is enhanced by the burning of fossil fuels and vegetation, which releases C into the atmosphere.

The C combines with O2 to form CO2 b. CO2 concentration and thus global temp has steadily increased over the last 150 years (industrial revolution)c. Future concerns?

1. Sea level rising (due to melting of glaciers and ice caps)

2. Changes in weather patterns (severe weather)

II. Ecosystem DamageA. Daily Environmental Damage

1. Chemical Pollution (in air, lakes, oceans) kills wildlife & aquatic life

2. Agricultural Chemicals pesticides (DDT), herbicides, fertilizers

Biological Magnification Chemicals breakdown slowly in env’t and collect in animal tissues Concentration of chemical is increased as it passes up thru the food chain

3. Consumption/Destruction of resources

a. Species extinction: due to habitat loss (ex. deforestation

b. Loss of topsoil: due to overgrazingc. Ground water:

1. Loss due to watering lawns, leaky faucets2. Pollution b/c of improper chemical waste disposal

4. Human Population a. possibly the single greatest threat b. Its continued exponential growth will cause an

increase in waste, depletion of resources and habitat c. however, new technology is allowing for better

sanitation, recycling, medical care, etc.

III. Environmental Solutions

Reduce global pollution1. Stop CFC production2. Restricted use of DDT and asbestos in U.S.3. Reduce air pollution by decreasing

emissions of CO2, sulfur dioxide, soot4. Better sewage facilities5. Conserve energy (car pooling)6. Recycle