Ecology

What is Ecology

• Ecology – the study of the interactions between organisms and the living and nonliving components of their environment.

• Levels of Organization– Biosphere– Ecosystem– Community– Population– Organism

Levels of organization within an ecosystem

• Organism – an individual living thing

• Species – a group of organisms that can mate to produce fertile offspring

• Population – all the members of the same species that live in the same place at the same time– Members of a population generally breed with

one another rather than members of other populations

• Community – a group of various species that live in the same place and interact with each other– Only made up of BIOTIC components

Defining an Ecosystem

• Ecosystem – all of the organisms living in an area together with their physical environment– Ex. An oak forest, a coral reef, a mangrove swamp

• Biosphere – the thin volume of Earth and its atmosphere that supports life.

Biotic and Abiotic

• Biotic factors – the living and once living parts of an ecosystem– Plants and animals– Dead organisms

• Abiotic factors – nonliving parts of an ecosystem– Air– Water– Rocks– Light– Temperature

Taxonomy and Ecology Review1. What is taxonomy? Why bother to classify organisms?2. What is the purpose of a scientific name?3. What two taxa make up an organisms scientific name? How is this

scientific name correctly written?4. Write these scientific names correctly:

– mola mola – homo sapians – tyrannosaurus rex

5. What are the different taxonomic groups? What is the broadest, most inclusive? What is the smallest and most specific?

6. What is ecology?7. What are the levels of organization in ecology from smallest to

largest?8. What is the difference between an ecosystem and a community?9. What are biotic and abiotic factors?

Habitat

• Habitat – the place an organism lives• Habitats have everything (biotic and abiotic)

that the organism needs to survive• Organisms are well suited for their habitats• Very specific biotic and abiotic conditions

Organisms in a Changing Environment

• Tolerance curve – a graph of performance vs. values of an environmental variable

Organisms in a Changing Environment

• Acclimation – some organisms can adjust their tolerance to abiotic factors– Example – Goldfish

• Organisms deal with changes in their environment in one of two ways:1. Conformers – do not regulate their internal

conditions, change as the environment changes2. Regulators – use energy to control some of their

internal conditions to keep them in an optimal range

Organisms in a Changing Environment

• What happens when conditions are unfavorable?– Migration – movement to a more favorable

habitat– Dormancy – a state of reduced activity during a

period of unfavorable conditions

Niche

• Niche – the specific role or way of life of a species within its environment– Often thought of as its “job” or what it does

• Generalist species – have a broad niche; can tolerate a wide range of conditions and use a variety of resources

• Specialist species – have a very narrow niche; have very specific dietary requirements, live in only specific conditions

Self Quiz

• What are the main levels of organization in ecology? How do they differ?

• What are biotic and abiotic ecosystem components?

• What is a habitat? What is a niche? How do they differ?

• What is a tolerance curve?

Producers and Consumers

• Producer – an organism that makes its own food– Also called autotrophs– Example: Plants

• Consumers – organisms that get their energy by eating other organisms– Also called heterotrophs– Example: Rabbits, Cows, Deer, Wolves

What eats what?

• Herbivores – plant eaters• Carnivores – meat eaters• Omnivores – eat both plants and meat• Detritivores/decomposers - get their food by

breaking down dead organisms

Productivity• Production - the synthesis and storage of organic molecules

during the growth and reproduction of photosynthetic organisms• Gross primary productivity (GPP) – the rate at which producers in

an ecosystem capture the energy of sunlight by producing organic compounds– (think photosynthesis)

• Biomass – the organic material that has been produced in an ecosystem. Producers (plants) making organic molecules (like glucose!)

• Net primary productivity (NPP) – the rate at which biomass accumulates in an ecosystem.– NPP = GPP - respiration

Estimated Annual Average NPP in Major Life Zones and Ecosystems

Food Chain

• A linear sequence in which energy is transferred from one organism to the next as each organism eats another organism

Food Chain

Food Web

• Shows many feeding relationships that are possible in an ecosystem.

• Much more complex than a food chain

Food Web

Energy Transfer in an Ecosystem

• Trophic level - each step in the transfer of energy through a food chain or food web in an ecosystem

• Energy is lost each time energy is transferred from one organism to another

Trophic Levels

• Only 10% of the energy is transferred from one trophic level to the next.

• For every 1,000 producers, 1 tertiary consumer

Trophic Levels

Self Quiz

• How does energy transfer through an ecosystem. Explain the number of higher level consumers that can be present?

• What are autotrophs? Heterotrophs?• What is the difference between a food chain

and a food web?• What is productivity?

Ecosystem Recycling

• Biogeochemical cycles – the circulation of substances through living organisms from or to the environment– Water Cycle– Carbon Cycle– Nitrogen Cycle– Phosphorus Cycle

The Water Cycle

The Water Cycle

• The water cycle involves– Evaporation – Condensation – Precipitation– Transpiration – the process by which water

evaporates from the leaves of plants in terrestrial ecosystems

The Carbon Cycle

• The process by which carbon is cycled between the atmosphere, land, water, and organisms.

The Carbon Cycle

• Link between photosynthesis in producers and respiration in producers, consumers, and decomposers

• Movement of carbon from the nonliving environment to living things and back.

The Carbon Cycle

• Plants take in CO2 from the atmosphere through photosynthesis

• Animals eat plants• Animals release CO2 through respiration• Some carbon may be converted into

carbonates, which make up the hard parts of bones and shells– Deposit into carbon sinks– Over time, these become fossil fuels

Nitrogen Cycle

• Nitrogen cycle - process in which nitrogen is cycled between the atmosphere, bacteria, and other organisms.

• Nitrogen makes up 78% of atmosphere– Not in a form most organisms can use

• Nitrogen fixing bacteria - fix atmospheric nitrogen into chemical compounds that organisms can use

Nitrogen Cycle

Nitrogen Cycle

• Nitrogen-fixing bacteria live within nodules on the roots of plants called legumes– beans, peas, and clover

• Plants that do not have nitrogen-fixing bacteria in their roots get nitrogen from the soil.

• Animals get nitrogen by eating plants or other animals.

Nitrogen Cycle

• Decomposers break down wastes and return the nitrogen that these wastes and dead organisms contain to the soil in a process called ammonification.

• Nitrification – the process by which soil bacteria uptake ammonium and form it into nitrites

• Denitrification – occurs when anaerobic bacteria break down nitrates and release nitrogen gas into the atmosphere.

Phosphorus Cycle

• Phosphorus cycle – the movement of phosphorus from the environment to organisms and then back to the environment

• Very slow cycle• No atmospheric component (Carbon and

Nitrogen cycles do)

Phosphorus Cycle

Phosphorus Cycle

• Rocks erode• Phosphate dissolves in water• Plants absorb phosphate through roots• Excreted when organisms decompose

Self Quiz

• Summarize the carbon cycle.• Summarize the nitrogen cycle• Summarize the phosphorus cycle.• How do humans have the potential to impact

each of these cycles?• Which is the only cycle without an

atmospheric component?