PRINCIPLES OF ECOLOGY

WHAT IS ECOLOGY? From the Greek work oikos meaning “house” The study of the interactions of living organisms with one another and with their environment 1866 Ernst Haeckel, German biologist coined the term

ECOLOGISTS STUDY ENVIRONMENTS AT DIFFERENT LEVELS OF ORGANIZATION

LEVELS OF ORGANIZATION Organism: an individual living thing Population: a group of the same species that lives in one area Community: a group of different species that live together in one area Ecosystem: includes all of the organisms as well as the climate, soil, water, rocks, and other nonliving things in a given area Biome: a major regional or global community of organisms; usually categorized by climate conditions and plant communities that thrive there

ECOLOGICAL RESEARCH METHODS INCLUDE: OBSERVATION, EXPERIMENTATION, & MODELING

OBSERVATION Using the senses to study the world Using tools to collect measurements Examining previous research results

OBSERVATION Monitoring activities of a species – Direct survey: for species that are easy to follow (naked eye, binocular, etc.) – Indirect survey : for species that are difficult to track (feces, signs of a recent kill, etc.) – Radiotelemetry Population size – Mark recapture: mobile population – Quadrat: plant populations; stationary

EXPERIMENTATION Lab – Pros: controlled – Cons: does not reflect complex interactions that occur in nature Field – Pros: accurate picture of how organisms interact in a natural setting – Cons: difficult to determine cause and effect due to the large number of factors at work in nature

MODELING Computer and mathematical Test hypothetical situations but are based on real data

AN ECOSYSTEM INCLUDES BOTH BIOTIC AND ABIOTIC FACTORS

BIOTIC FACTORS An environmental factor that is associated with or results from the activities of living organisms

ABIOTIC FACTORS An environmental factor that is not associated with the activities of living organisms Examples: light, temperature, water, wind, etc.

CHANGING ONE FACTOR IN AN ECOSYSTEM CAN EFFECT MANY OTHER FACTORS

BIODIVERSITY The number and variety of organisms in a given area during a specific period of time

KEYSTONE SPECIES Organism that has an unusually large effect on its ecosystem

ENERGY IN ECOSYSTEMS

PRODUCER/AUTOTROPH An organism that can make organic molecules from inorganic molecules A photosynthetic or chemosynthetic autotroph that serves as the basic food source in an ecosystem

CHEMOSYNTHESIS Process by which ATP is synthesized by using chemicals as an energy source instead of light

CONSUMER/HETEROTROPH An organism that eats other organisms or organic matter instead of producing its own nutrients or obtaining nutrients from inorganic sources

TYPES OF CONSUMERS Herbivores Carnivores Omnivores Detritivores Decomposers Generalists

HERBIVORE An organism that eats only plants

CARNIVORE An animal that eats other animals

OMNIVORE An organisms that eats both plants and animals

DETRITIVORE A consumer that feeds on dead plants and animals organisms that eat detritus, or dead organic matter

DECOMPOSER Detritivores that break down organic matter into simpler compounds An organisms that feeds by breaking down organic matter from dead organisms Examples: bacteria and fungi

GENERALIST Consumers that have a varying diet Do not rely on a single food source Example: gray wolf

FOOD CHAINS AND FOOD WEBS

TROPHIC LEVELS Levels of nourishment in a food chain Primary consumers Secondary consumers Tertiary consumers

A FOOD WEB SHOWS A COMPLEX NETWORK OF FEEDING RELATIONSHIPS Arrows point in the direction of energy flow Arrows point to the one doing the “eating”

AN ENERGY PYRAMID SHOWS THE DISTRIBUTION OF ENERGY AMONG TROPHIC LEVELS

ENERGY PYRAMID Each row in the pyramid represent a trophic (feeding) level in an ecosystem The area of a row represents the food chain pathways of energy transfer through various stages as a result of the feeding patterns of a series of organisms

OTHER PYRAMID MODELS ILLUSTRATE AN ECOSYSTEM’S BIOMASS AND DISTRIBUTION OF ORGANISMS

BIOMASS Organic matter that can be a source of energy The total mass of the organisms in a given area

CYCLING OF MATTER

HYDROLOGIC/WATER CYCLE Pathway of water from the atmosphere to Earth’s surface, below ground, and back

HYDROLOGIC/WATER CYCLE Water has the greatest nonliving influence on an ecosystem’s inhabitants Ground Water: water that is beneath the Earth’s surface as a result of rain or snow Most water evaporates back into the atmosphere

HYDROLOGIC/WATER CYCLE Transpiration: the process by which plants release water vapor into the air through stomata Also the release of water vapor into the air by other organisms

ELEMENTS ESSENTIAL FOR LIFE ALSO CYCLE THROUGH ECOSYSTEMS

BIOGEOCHEMICAL CYCLES The circulation of substances through living organisms from or to the environment All materials that cycle through living organisms are important in maintaining the health of ecosystems

THE OXYGEN CYCLE Plants release oxygen as a waste product during photosynthesis Humans and other organisms take in oxygen and give off carbon dioxide in respiration Plants use carbon dioxide for photosynthesis

THE CARBON CYCLE Organisms need carbon to build organic molecules 3 ways in which carbon may return to the atmosphere – Respiration – Combustion – Erosion

PHOSPHOROUS & NITROGEN CYCLES Organisms need nitrogen and phosphorous to build proteins and nucleic acids Phosphorous is present in soil and rock as calcium phosphate…used by plants and used to build organic molecules The atmosphere is about 78%, N 2 Must be converted in order for organisms to use it

NITROGEN FIXATION The process by which gaseous nitrogen is converted into ammonia Ammonia: a compound that organisms can use to make amino acids and other nitrogen-containing organic molecules

THE NITROGEN CYCLE Assimilation – The absorption and incorporation of nitrogen into organic compounds by plants Ammonification – The production of ammonia by bacteria during the decay or organic matter

THE NITROGEN CYCLE Nitrification – The production of nitrate from ammonia Denitrification – The conversion of nitrate to nitrogen gas

THE PHOSPHOROUS CYCLE