EcologyEcologyAn introduction…

Question

Are organisms, including humans, “islands”. Why or why not? Support your answer.

Ecology Defined

• Ecology is the interaction between biotic and abiotic factors in an environment.

• So what is a biotic factor anyhow?

Biotic Factors

• The living factors in an ecosystem• Examples:

• We investigate how these factors influence different species.

• So what is an abiotic factor?

Abiotic Factors

• The non-living things in an ecosystem.

• Draw an ecosystem with 5 biotic factors and 5 abiotic factors.

Levels of Biological Organization in Ecology

1. Biosphere2. Ecosystem3. Community4. Population5. Organism

Which is the largest?

Biosphere

• The portion of the Earth that supports life.

• So what does that mean? Where does it start? Where does it end?

Ecosystem

• Interactions among the populations in a community and the community’s physical surroundings, or abiotic factors.

• Two general types– Terrestrial– Aquatic

Community

• A collection of interacting populations.

• EG: Hawks & Mice

Population

• A group of organisms of one species that interbreed and live in the same place at the same time.

Organism• A living thing • When discussing organisms,

biologists always discuss their habitats and niche.

• What are the differences between an organism’s habitat and niche?

Habitat vs. Niche

• Habitat: Where the organism lives.

• Niche: An organism’s role or position – job. More specifically it is how it survives, and reproduces. It include all of its interactions with the biotic and abiotic parts of its habitat.

Question

• Why would it be beneficial for a species to occupy a niche different from those of other species?

• Reduction of competition.

Symbiosis

• Relationships between living things.

• Three types. Do you know what they are?

Types of Symbiosis

• Mutualism– Both species benefit

• Commensalism– One species benefits, other is not

harmed• Parasitism

– One species benefits, other is harmed

Nutrition & Energy FlowNutrition & Energy Flow

Question

• How do different types of organisms obtain energy? hint: think of plants vs. fungi vs. animals

3 Ways Organisms Obtain Energy

1. Autotrophs– Organism that uses light or chemical

energy to make energy-rich compounds2. Heterotrophs

– Can not make its own food– Feeds on other organisms– Herbivore, Carnivore, Scavengers,

Omnivores3. Decomposers

– Break down complex compounds of dead and decaying plants

Food Chain

• Can you give a simple example of a food chain?

Trophic Levels

• Example Food Chain• Grass -> Mouse -> Snake -> Hawk• Grass = Producer• Mouse = Primary Consumer• Snake = Secondary Consumer• Hawk = Tertiary Consumer

Trophic Level

Food Web Food webs show all possible

feeding relationships as opposed to the more simplistic model of the food chain.

Food Web

Food Chain vs Food Web

Pyramids of Energy Pyramids of energy show

the relative amount of energyavailable at each trophic level.

Organisms expend much of the energy they acquire on life processes, such as respiration, movement, growth, and reproduction. Most of the remaining energy is released into the environment as heat—a byproduct of these activities.

On average, about 10 percent of the energy available within one trophic level is transferred to the next trophic level.

Pyramids of Biomass & Numbers The amount of living tissue in trophic level is called its

biomass. The amount of biomass a trophic level can support is determined, by the amount of energy available.

? Where is the greatest biomass in the picture below ? A pyramid of biomass - the relative amount of living

organic matter at each trophic level. A pyramid of numbers - shows the relative

number organisms at each trophic level. In most ecosystems, the shape of the

pyramid of numbers is similar to the shape of the pyramid of biomass for the same ecosystem, with the numbers of individuals on each level decreasing from the level below it.

? Can you think of examples where this is not true?

Cycles In Nature• Water Cycle

– Evaporation, transpiration, condensation, precipitation, run-off, percolation

• Carbon Cycle– All life on earth is based on carbon– Burning, photosynthesis, respiration, death

• Nitrogen Cycle– Fixation, Protein, Urination, death, denitrification

• Phosphorus Cycle– Erosion, Phosphate in Soil, Plants, Herbivores &

Carnivores, Waste/Death, dissolved in H2O, sediments, rock, plankton, birds

Carbon Cycle

http://www.kidsgeo.com

Carbon Cycle

http://www.scionline.org

Water Cycle

http://www.coe.ilstu.edu

Copyright © McGraw-Hill Companies Permission required for reproduction or display

Nitrogen Cycle

http://www.kidsgeo.com

Copyright © McGraw-Hill Companies Permission required for reproduction or display

Phosphorus Cycle

http://hydram.epfl.ch

Phosphorus Cycle

http://arnica.csustan.edu