Ecology

Chapter 2: Principles of Ecology

Chapter 3: Communities and Biomes

Principles of Ecology

2-1: Organisms and Environment

2-2: Nutrition and Energy Flow

Communities and Biomes

3-1: Communities

3-2: Biomes

2-1: Organisms & the Environment

• Ecology: study of interactions between organisms and their environment

• Explains how organisms affect each other and the world they live in

• Environment can either be living or non-living

Non- living Environment• Abiotic factors: the non-living parts of

an organism’s environment

• Examples include air currents, temperature, moisture, light, and soil.

Living Environment• Biotic factors: all the living organisms

that inhabit an environment

• All organisms depend on others directly or indirectly

Abiotic or Biotic?

Biotic

Abiotic or Biotic?

Abiotic

Levels of Organization• All organisms are organized into levels

cells

organismorgan

systems

organs

tissues

• The interactions of the organism are then organized depending on complexity

1st Level • Organism

– individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops

– at this level species are studied•species: group of similar organisms that

can interbreed and produce fertile offspring

2nd Level • Population

– A group of organisms that interbreed and live in the same place at the same time

– Have to be same species to be a population

3rd Level

• Community– all the interacting

populations in a certain area at a certain time

– change in one population may cause changes in the other populations Ex. hawks and mice

4th Level

• Ecosystem– interacting

populations in a community and the community’s abiotic factors

– terrestrial or aquatic– subject to change

Ex. forest, compost heap, pond

5th Level

• Biosphere– the portion of Earth

that supports life– extends from high

atmosphere to bottom of oceans

Organism

Community

Ecosystem

Population

Biosphere

Organisms in Their Environment

• Habitat: place where an organism lives out its life– Ex. bottom of a stream

• Niche: all strategies and adaptations a species uses in its environment– organism’s way of life

Relationships

• Predation– predator seeks

out and eats prey• Ex. cheetah

hunting down antelope

– constant battle for survival

preypredator

Relationships

• Symbiosis– close and

permanent association between organisms of different species

– they live together– helps maintain

their survival– 3 types of

symbiosis

Symbiosis

• Mutualism– symbiotic

relationship where both species benefit

– Ex. Ants and Acacia Trees

Symbiosis

• Commensalism– symbiotic

relationship where one species benefits and the other is neither harmed nor benefited

– Ex. Clownfish and Sea Anemones

Symbiosis

• Parasitism– symbiotic

relationship where one species benefits at the expense of the other

– species that is harmed is called a host

– Ex. Fleas and Animals

2-2: Nutrition & Energy Flow

• ultimate source of energy for all life (directly or indirectly) is the sun

• some convert sunlight into energy--• an organism that

uses light energy to make their own food is a producer or autotroph

plants

Obtaining Energy

• Producers then feed consumers– organism that cannot make its own food

and feeds on other organisms; also called heterotroph

• Heterotrophs can be carnivores

herbivoresor

omnivores

Food Chains

• Matter and energy move through ecosystems from producers to consumers

• Some energy is also transferred to the environment as heat

• Food chain:– model showing how matter and energy

move through an ecosystem– Nutrients and energy move fromAutotrop

hHeterotroph Decompose

r

Food Chains

• Arrows indicate direction energy is transferred

• Each organism represents a trophic level or a feeding step

• First level is always a producer• Remaining levels are

consumers and can be divided into different orders

Consumers Can Be:

• 1st order heterotroph (primary consumers):

•feeds on plants•grasshoppers, deer, mice

• 2nd order heterotroph (secondary consumers):

•feeds on 1st order heterotroph•frogs, snakes, small birds, etc.

• 3rd order heterotroph (tertiary consumers):

•feeds on 2nd order heterotroph•owls, coyotes, snakes, etc.

Food Webs

• Food chains only show one route of matter and energy transfer

• Ecosystems typically have more than one route– Ex. Snakes eat mice that eat producers,

but also eat frogs that eat 1st order consumers. So what is the snake, and how is energy transferred?

• Food web: shows all the possible feeding relationships at each trophic level in a community

Food Webs

• Represents a network of interconnected food chains

Ecological Pyramids

• another way to show how energy flows

• Energy pyramids show:– Only 10% of energy is available to

next level– large # of producers to support small # of primary consumers– large # of primary consumers to support small # of secondary consumers

100%

0.1%

1%

10%

Cycles in Nature

• Matter is also transferred; does not disappear but is constantly cycled

• Three main elements that must move through an ecosystem are:– Water– Carbon– Nitrogen

Water Cycle

Carbon Cycle

Nitrogen Cycle

3-1: Communities• What is a community?

– all the populations in a certain area at a certain time

• Are all parts of the world suitable for every organism?– No

Limiting Factors

• any factor that restricts the number of individuals in a population

• affects an organism’s ability to survive in its environment

• Examples:

waterfood predator

s

temperature

space sunlight

soil

Tolerance

• range of factors under which an organism functions & survives

Organisms absent

Organisms infrequent

Greatest number of organisms

Organisms infrequent

Organisms absent

Zone of intolerance

Zone of physiological

stress

Optimum range

Zone of physiological

stress

Zone of intolerance

Range of tolerance

Pop

ulat

ion

Lower limit Upper limit

Succession

• orderly, natural changes and species replacements that occur in communities over time

• occurs in stages; different species may be present at each stage

• 2 types– primary– secondary

Succession

• Primary– colonization of barren land by communities

of organisms– takes place where there are no living

organisms– first species to take hold are pioneer

species– Example

• Lava destroys everything and forms new land• Lichen begins growing—pioneer species

Succession

• Secondary– takes place after an existing community

is disrupted in some way– occurs in areas that previously

contained life and on land that still contains soil

– Example• Forest fires destroy communities, but soil is

still available• Species begin coming back

• After some time, succession slows down and the community becomes fairly stable

• Climax community– stable mature community that undergoes

little or no change

3-2: Biomes• large group of ecosystems that share

similar climates and organisms• terrestrial or aquatic

Aquatic Biomes• Marine biomes

– 4 marine groups•Estuaries•Intertidal zones•Photic zones•Aphotic zones

• Freshwater biomes

Estuaries

• occur where rivers join oceans and freshwater mixes with salt water

• salinity can change allowing a wide range of organisms to live here

• most are used as “nurseries”

• Organisms include:– snails, crabs, shrimp,

clams, fishes, birds, grasses

Intertidal Zone

• portion of shoreline lying between high and low tide zones

• changing oxygen and nutrient levels

• crashing waves• organisms include

snails, sea stars, barnacles, clams, crabs

Photic Zone• portion of marine biome shallow

enough for sunlight to penetrate• many diverse species• plankton is abundant (small organisms

that drift and float in photic zone)• includes corals, fishes,

sea plants, etc.

Aphotic Zone

• portion of marine biome where light does not penetrate

• organisms include crabs, squids, octopi, fishes, etc.

Freshwater Biomes• ponds, lakes, rivers,

streams• includes organisms

that not only live in the water but those that go on land as well

• organisms include frogs, snails, fish, turtles, plants, etc.

Terrestrial Biomes

• Think about traveling from north pole to equator—what changes would you observe? Why?

• Latitude describes north-south position from equator

• Latitude and climate are directly related

• Latitude affects climate (temperature, precipitation, etc.)

• Small differences in temp. and precip. can create different biomes

Tundra

• treeless land with long summer days and short period of winter sunlight

• temperatures barely rise above freezing

• permafrost—permanently frozen layer of ground

• soil contains little nutrients• little to no precipitation

Taiga

• also called boreal forest• made mostly of coniferous trees—fir,

spruce, hemlock—with poor acidic topsoil

• weather is harsh, but milder than tundra• cold winters, little precipitation• more organisms

than tundra

Desert

• arid region with little to almost no plant life

• driest biome; less than 23 cm precip/year

• temperatures can be extremely high or extremely cold

• vegetation varies depending on rainfall

Grassland• large communities

covered with rich soil and grasses

• have more rain than deserts, but not enough to support tree growth

• increased diversity• also called prairies,

steppes, and pampas

• Savannas are like grasslands, but receive enough rain to support trees

American Buffalo

Temperate Forest

• deciduous forests with broad-leaved hardwood trees; 70-150 cm of precip/yr

• in temperate zone—goes through seasons

Rain Forests

• forests receiving extensive amounts of rainfall; at least 200 cm/yr

• can be temperate or tropical• Tropical

– warm weather, wet weather, lush plant growth

– near equator– greatest biodiversity– poor soil; nutrients recycled quickly