Ecology Chapters 15, 16 &17 Mrs. Cook Biology. Ecological Organization Ecology is the study of the interactions between organisms and the living and nonliving

EcologyChapters 15, 16 &17

Mrs. Cook

Biology

Ecological Organization

• Ecology is the study of the interactions between organisms and the living and nonliving components of their environment.


5 Levels of Ecological Organization

1. Organism• The simplest level of organization in ecology• Research concentrates on the adaptations that

allow organisms to overcome challenges of their environment


2. Population• A Population includes all the members of a species

that live in one place at one time.


3. Community-• A community is all the interacting organisms living

in an area• Ecologists often focus on how species interact and

how these interactions influence the nature of the community


4. Ecosystem-• An ecosystem includes all of the organisms and

the nonliving environment found in a particular place

• Examples: -a pond or a Forrest


5. The Biosphere• The Broadest, most inclusive level• The Biosphere is the thin volume of earth and

its atmosphere that supports life• All organisms are found in the biosphere• Living things are not evenly distributed

throughout the biosphere

Identify which part of ecological organization each picture is….

Ecosystem Components

1. The Non-living factors, called Abiotic Factors, are the physical and chemical characteristics of the environment.

• Temperature• pH• Humidity• Salinity• Oxygen Concentration• Amount of Sunlight• Availability of Nitrogen• Precipitation


2. The living components of the environment are called Biotic Factors

- they include all of the living things that affect the organism

• Food that it eats• Mates• Children• Living shelter (trees, shrubs, tall grass)


3. Habitat- where a species lives (like its address)

- tropical rain forest

- savannah of Africa

- Laurel Mountains

4. Niche- role in its environment

- which includes


4. Niche- role in its environment (its job)

- which includes:• Range of conditions that the species can

tolerate• The resources it uses• The methods by which it obtains its resources• The number of offspring it has• Its time of reproduction• All the other interactions with its environment


a. Generalists- are species with broad niches

- They can tolerate a range of conditions and use a variety of resources

ex: raccoon, cockroach


b. Specialist- species that have narrow niches are call specialist.

ex. Koala, Panda Bear


c. Some species change niches during their life time-

ex. Caterpillars

Energy Flow through an ecosystem

1. Primary Energy Source-• Produces: organisms that first capture energy in

an ecosystem; includes plants, bacteria and some algae.

• Primary Productivity: the rate at which organic material is produced by photosynthetic organisms

• Consumers- All other organisms in an ecosystem need to consume plants or other organisms to obtain the energy to build their molecules.


2. Trophic Levels- how energy flows through an ecosystem by assigning organisms a specific level based on the organisms source of food.

a. First Level

- lowest level of ecosystem

- occupied by the producers


b. Second Level

- herbivores- animals that eat plants or other primary producers

- primary consumers

Energy Flow through an ecosystemc. Third Level

- secondary consumers

- Carnivores- animals that eat other animals

- Omnivores- eat both plants and animals

- Detritivores- obtain energy from the organic wastes and dead bodies that are produced at all trophic levels; worms, fungi, and bacteria

- Decomposers- Bacteria and fungi because they cause decay and return nutrients to the soil


d. Forth Trophic Level

- carnivores that eat other carnivores

- called Tertiary consumer

- top carnivores

3. Energy Pyramid- represents each trophic level. The lowest trophic level is on the bottom. The width of each block is determined by the amount of energy stored by the organisms at each level. Only 10% of the energy can be passed from one level to the next.

1000 blades of grass

100 rabbits

10 fox

1 wolf


3. Food Chains and Food Webs

a. Food Chain- path of energy through the trophic levels of an ecosystem


b. Food Web- complicated, interconnected group of food chains. Most organisms feed at several trophic levels.

Biotic Interactions in an Ecosystem

1. Predator vs. Prey• In Predation, and individual of one species, called

the Predator, eats all or part of an individual of another species, called the Prey.

- Herbivores- predators that eat plants

- Carnivores- predators that eat animals

- Omivores- predators that eat both


2. Predator Adaptations-

- Natural selection favors the evolution of predator adaptations for finding, capturing, and consuming prey.

- Prey detection mechanisms, camouflage, adapted mouth parts, and speed are all examples of adaptations.

- Natural selection also favors adaptations in prey that allow the prey to escape, avoid, or otherwise ward off predators.

http://www.youtube.com/watch?v=UB7tqiL-Eqs


3. Symbiosis- a close, long term relationship between two organisms

There are THREE types:a. Parasitism- • Similar to predation in that one organism,

called the Host, is harmed and the other organism, called the Parasite, benefits.

• Does not result in immediate death of the host

• Hosts have evolved defense mechanisms- skin, tears, saliva, mucus, cells of the immune system



• b. Mutualism-• Is a relationship in which two species derive

some benefit from each other• Some are so close that neither species can

survive without the other• Pollination is one of the most important

mutualistic relationships on Earth

http://www.youtube.com/watch?v=Xm2qdxVVRm4


c. Commensalism-• Is an interaction in which one species benefits

and the other species is not affected• Species that scavenge for leftover food items

are often considered commensal species

How a Population Grows

• Every population has features that help determine its future.

Three Key Features of Populations:

1. Population Size

a. small populations

-most likely to become extinct

- random events or natural disasters (fire, flood), endanger small populations

- experience more inbreeding, reduce’s population fitness


b. Exponential Growth

- a curve in which the rate of the population grows steadily

ex: a bacteria that divides every 30 minutes will produce more than 1 mill bacteria after only 10 hours.


c. Carrying Capasity- population size that an environment can sustain.

• Boom and Bust Effect

-A population’s growth is limited by predators, disease, and the availability of resources.

- The population will eventually die back below the

carrying capacity.


Carrying Capacity of Reindeer in Pribilof Islands


d. Limiting factor• Any factor that restrains the growth of a

population is a limiting factor.

• Density Dependant Limiting Factors- the rate at which they become depleted depends upon the population density that uses them.

- space

- food

- water

- availability of mates

- disease


• Density- Independent Limiting Factors

-growth NOT dependent of the size of the population

- Weather and climate are the most important

Matter Recycled through an Ecosystem

• All Materials that cycle through living organisms are important in maintaining the health of ecosystems.

• Five important substances:• Water• Carbon• Nitrogen• Phosphorus• Oxygen

Matter Recycled through an Ecosystem1. Water Cycle-

• Key processes are

- Evaporation- water, heated by the sun or other means, re-enters the atmosphere

-Transpiration- evaporation from the leaves of plants

- Precipitation- water vapor condenses and falls to the earth surface as rain or snow.

• Ground Water- water that seeps into the ground as is stored beneath the earth’s surface.

Water Cycle

Matter Recycled through an Ecosystem2. The Carbon Cycle

• Photosynthesis and cellular respiration are the two main steps in the carbon cycle

• Key Processes are:

- Respiration- all organism release carbon as part of cellular respiration

- Combustion- burning of wood and fossil fuels such as coal, oil, and

natural gas

- Erosion- limestone was made from calcium carbonate shells of marine organisms. As limestone is becomes exposed & erodes, the carbon becomes available to other organisms

Carbon Cycle

Matter Recycled through an Ecosystem3. Nitrogen Cycle-

• Nitrogen is needed to build nucleic acids• Atmosphere is 78% Nitrogen but can’t be used in

this form

• Nitrogen Fixing bacteria- the change nitrogen gas into a usable form of

nitrogen for plants

- nitrogen combines with hydrogen to form ammonia. (NH3)

- bacteria found in soil and roots

Nitrogen Cycle


4. Phosphorus Cycle• Phosphorus moves from phosphate deposited in

rock, to the soil, to living organisms and finally to the ocean.

• It is an essential component in making ATP and DNA.

Phosphorus Cycle


5. Oxygen Cycle• Photosynthesis releases oxygen as a waste

product• Organisms use up the oxygen through respiration

and let off carbon dioxide• The carbon dioxide is then passed to the green

plants once again

Oxygen Cycle

Natural & Human Disturbances in an Ecosystem

• One of the most important characteristics of a community is how it responds to disturbance.

1. Disturbances- are events that change communities, remove or destroy organisms from communities, or alter resource availability.

a. Abiotic Disturbances

- drought, fires, floods, volcanic eruptions, earthquakes, storms


b. Biotic Disturbances

- Elephants tearing up trees while eating

- bulldozing

-clear cutting

-paving

-plowing

-mowing


2. Succession- • The gradual, sequential re-growth of a community

of species in an area is called Ecological Succession.

• Two Types of Succession-

- Primary Succession

- Secondary Succession


1. Primary Succession

- is the development of a community in an area that has not support life previously, such as bare rock, a sand dune, or an island is formed by volcanic eruption.


2. Secondary Succession-

- Is the sequential replacement of species that follows disruption of an existing community; occurs where soil is already present.

- following fire, floods, clear cutting, strip mining, etc.


3. Climax Community-• The community proceeds through a predictable series

of stages until it reaches a stable end point, called the climax community.

• Each stage pave the way for the next leading to the climax community which remains constant for a long period of time.

Biomes

• Biomes are very large climax regions that contain a number of smaller but related ecosystems within them.

• There are 8 Major Land Biomes…

Biomes

1. Tundra-• Cold and largely treeless Biome that forms a

continuous belt across Northern North America, Europe, and Asia.

• Largest and Northernmost Biome, covering 1/5th of the world’s land surface

• Permafrost- a permanently frozen layer of soil, under the surface, characterizes the tundra.

Biomes

2. Tropical Forest• Occur near the equator in the region between

23.5oN and 23.5oS, known as the tropics• Includes parts of Asia, Africa, South America, and

Central America• Stable temperatures and abundant rainfall make

them the most productive biome.• Have two seasons: Wet and Dry.• Have the highest species richness of all the

biomes.

Biomes

3. Temperate Forest • Occur in Eastern N.America, Western and Central

Europe, and Northeastern Asia.• Characterized by distinct seasons and a moderate

climate• Can be characterized by the type of tress that is

most common, such a coniferous trees, which bear seeds in cones and tend to be evergreen, or

• Deciduous trees, which shed their leaves in the fall and re-grow them in the spring- Temperate Deciduous Forests

Biomes

4. Taiga- • South of the Tundra and North of the Temperate

regions is the Taiga, a forested biome dominated by coniferous trees such a Pines, Firs, and Spruces

• Also called, Boreal forest, stretches across large areas of Northern Europe, Asia, and N. America between 50N and 60N.

Biomes5. Temperate Grasslands

• Usually form in the interior of continents at about the same latitude as temperate deciduous forests.

• Too dry to support trees• Once covered large areas of N. America, Asia,

Europe, Australia, and S. America• Have rich fertile soil

Biomes

6. Savanna• Tropical or Temperate grasslands that have scattered

deciduous tress and shrubs• Savannas of Africa are the best known, but this biome

also occurs in S. America and Australia• Receive more rain than deserts but less than tropical

or temperate forests do.

Biomes

7. Chaparral• Chaparral is a Biome that is dominated by dense,

spiny shrubs and has scattered clumps of coniferous tress

• Mild, rainy winters and hot, dry summers with periodic fires

• Found primarily in coastal regions

Biomes

8. Deserts• areas that receive an average of less than 25cm of

rainfall per year.• Large parts of North Africa, central Australia,

southwestern North America and Eastern Asia

Mojave Desert

Death Valley, Nevada

Documents

Ecology Chapters 15, 16 &17 Mrs. Cook Biology. Ecological Organization Ecology is the study of the interactions between organisms and the living and nonliving