Principles of Ecology Chapter 13. Ecologists Study Relationships Interactions and Interdependence Interactions and Interdependence Ecology – the scientific

Principles of Ecology

Chapter 13

Ecologists Study Relationships

• Interactions and Interdependence Ecology – the

scientific study of interactions among living things and their surroundings


• Biosphere - part of a planet (the earth) in which life exists including land, water, and air


Populations – individuals that live in the same area

Species – a group of individuals that can interbreed


Communities – assemblages of different populations that live togetherCommunities are within the ecosystem

(Ex. A reef in the ocean)


Ecosystem – a collection of all organisms that live in a particular place with their nonliving, or physical environmentScientists often

study species, populations, or communities in an ecosystem.


• Levels of OrganizationBiome – a group

of ecosystems that have the same climate and similar dominant communities


• Ecological MethodsObserving – first step

Long term studies more beneficial-ecological change takes time

SurveysDirect Indirect

Determining Population Size

Catch and releaseQuadrat Sampling


Experimenting – used to test hypothesesCan do in the

field or labLab-more control,

not a true reflection

Field-More accurate, difficult to determine cause and effect relationships


Modeling – gain insightComputersMathematical

modelsUse actual

data to simulate

Data collected using satellite technology

Biotic and Abiotic Factors

• Living and Non-living components– Biotic - living

factors– Abiotic -

nonliving things

Biotic and Abiotic Factors

• Biodiversity– The assortment,

or variety of living things

– Dependent on temperature, moisture

– Keystone Species – species that have a large impact on ecosystems

Energy in Ecosystems• Producers –

organisms that make their own food Autotrophs –

organisms that use energy from the sun or chemicals to make food

Energy in EcosystemsEnergy from the

sun• Photosynthesis

– Autotrophs use light energy to power chemical reactions that make energy

– Uses CO2

– Makes O2 and Carbs

Energy in Ecosystems

Life without light• Chemosynthesis – Use chemical

energy to make carbohydrates– Bacteria deep in the ocean

Energy in Ecosystems• Consumers –

Organisms that need other organisms for their energy and food supply These are also referred

to as heterotrophs

Food Chains and Food Webs

• Feeding Relationships• Food Chains – A series of energy

transferring steps


Types of heterotrophs• Herbivores

– Energy from eating plants

• Carnivores– Energy from eating animals

• Omnivores– Both plants and animals

• Detritivores– Feed on the remains of

dead matter

• Decomposers– Break down organic matter

for energy


• Specialist– Consumer that

primarily eats one specific organism

• Generalist– Have a varying

diet


Trophic Levels – Each step in a food chain or web• First level is producers• Second level on is

consumers-usually herbivores

• Tertiary consumers are usually carnivores

• Each consumer depends on the trophic level below it

Food Chains and Food WebsFood Webs – Feeding relationships

among many organisms in an ecosystem form a network of interactions

Cycling of Matter• The Hydrological Cycle (Water

Cycle)– Evaporation – Water changes from a

liquid to a gas– Transpiration – Evaporation from the

leaves of a plant

Cycling of MatterClouds form from tiny drops of water

collecting called condensation

Cycling of Matter• Recycling in the Biosphere

Biogeochemical cycles• The transforming of matter by biological

systems

– Energy moves in a one way fashion – Nutrients recycle

Cycling of Matter• Nutrient Cycles

Nutrient – All the chemical substances that an organism needs to sustain life

Cycling of Matter• Oxygen Cycle

– Most organisms use oxygen need oxygen

– Plants release oxygen

– Living organisms release carbon dioxide as a waste product

Cycling of MatterThe Carbon Cycle

• Carbon is passed on from one situation to another throughout the biosphere

– Photosynthesis uses CO2 to make carbs

– Carbs are eaten by other organisms

– Organisms exhale CO2

during cellular respiration– All organisms eventually

decay and the carbon is converted to coal or petroleum

– Burning things releases stored CO2 into the atmosphere

Cycling of MatterThe Nitrogen Cycle

• All organisms need nitrogen to make amino acids

– What do amino acids make?– Proteins– 78% of Earth’s atmosphere

Nitrogen gas (N2)– Other types:– Ammonia (NH3)

Nitrate (NO3) Nitrite (NO2)

– Nitrogen fixation – N2 to NH3

– Denitrification - NO3 to N2

Cycling of Matter– The Phosphorus

Cycle• DNA and RNA

need phosphorus • This element does

not go into the atmosphere

• Phosphorus works its way through the food web

Cycling of Matter• Nutrient Limitation

– Ecologists look at the rate of production of producers – Primary Producivity

– Availability of nutrients can limit an ecosystem

– Limiting nutrient• Ecosystem limited by

one nutrient– Nitrogen in the ocean is the

limiting nutrient• 0.00005% nitrogen• If runoff causes a drastic

increase in nitrogen, then an algae bloom occurs

Pyramid Models• Ecological Pyramids – diagram

that shows how much energy is transferred at each trophic level

Pyramid ModelsBiomass Pyramid

• Biomass – Total amount of living tissue in a level

– Represents the amount of potential food available at each trophic level

Pyramid ModelsEnergy Pyramid

• Only about 10 % of the energy is transferred to the next trophic level

– More levels means less energy at the last level

Pyramid ModelsPyramid

NumbersShows how many

individuals there are in each level

Documents

Principles of Ecology Chapter 13. Ecologists Study Relationships Interactions and Interdependence Interactions and Interdependence Ecology – the scientific