What is ecology?What is ecology?

Ecology- watch the videoEcology- watch the video

EcologyEcology• Ecology = scientific study of the interactions

among organisms and between organisms and their environment (surroundings)

• Each organism plays a role in their “household” (the environment) = ‘niche’

• Interactions produce a web of interdependence between organisms and the environment

• The environment and interactions are constantly changing (dynamic)

Levels of Organization-big->smallLevels of Organization-big->small• Biosphere = portions of the planet where all life

exists (land, water, air, etc)• Biome = group of ecosystems that have the same

climate and similar dominant communities• Ecosystem = collection of all the organisms that live

in a particular place together with their nonliving (physical) environment

• Communities = different populations that live together in a defined area

• Populations = groups of individuals that belong to the same species and live in the same area

• Species = group of organisms so similar that they can breed and produce fertile offspring

• Individual = one member of a specific species

Section 3-1

Figure 3-2 Ecological Levels of Organization

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Energy flowEnergy flow

• Every organism needs energy to power life’s processes

• Energy is obtained through interactions with the environment

• The flow of energy through an ecosystem is one of the most important factors that determines the system’s capacity to sustain life

PopulationsPopulations

• INCREASES– immigration; higher birth rate than death rate

• DECREASES– emmigration; higher death rate than birth rate

ProducersProducers• Sunlight is the main energy source of life on Earth• Only plants & certain bacteria can capture energy from

sunlight or inorganic chemicals and use that energy to produce food = autotrophs

• Autotrophs are also called producers, – Some autotrophs use light energy to convert carbon

dioxide & water into oxygen & sugars through the chemical reaction photosynthesis (plants/algae)

– Some use chemical energy to produce carbohydrates in absence of light through chemosynthesis (bacteria)

ConsumersConsumers• Must acquire energy from other organisms =

heterotrophs• Heterotrophs are also called consumers

– Herbivores = eat only plants– Carnivores = eat only animals– Omnivores = eat both plants and animals– Detritivores = eat plant/animal remains and other

dead matter called detritus– Decomposers = break down organic matter

Feeding RelationshipsFeeding Relationships• Energy flows through an ecosystem in one

direction

• Energy flows from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)– FOOD CHAIN

• Feeding relationships among organisms in an ecosystem usually form a network of complex interactions shown as a food web

• Each step in a food chain/web = trophic level

Food ChainFood Chain

Section 3-2 Food Web

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Trophic LevelsTrophic Levels

• Each step in a food chain or web is a trophic level.– The first trophic level is the producers. – The second trophic level is the consumers

(herbivores).– The third and fourth levels are more

consumers (omnivores and the carnivores).

Ecological Pyramids-watchEcological Pyramids-watch

Ecological PyramidsEcological Pyramids• The amount of energy or matter in each trophic level of a food

chain/web of an ecosystem can be represented by an ecological pyramid

– Energy pyramid = only about 10% of the energy stored in one trophic level is passed on to the next higher level, because most of the energy is used for life processes and some is released into the environment as heat

– Biomass pyramid = potential total amount of living tissue within a given trophic level (grams per unit area) for each trophic level in an ecosystem

– Pyramid of numbers = relative number of individual organisms at each trophic level

Pyramid of NumbersShows the relativenumber of individualorganisms at eachtrophic level.

Biomass PyramidRepresents the amount ofliving organic matter at each trophic level. Typically, thegreatest biomass is at the base of the pyramid.

Energy PyramidShows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat.

Section 3-2

Ecological Pyramids

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