unit 3 ppt - chap 5b - interactions

8/12/2019 Unit 3 PPT - Chap 5b - Interactions

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11/12/20

Unit 3 - Chapter 5, Part 2

Interactions: Environments and Organisms

Edited by Reneau Peurifoy

Interactions: Environments and Organisms

Outline

5.3 Organism Interactions

5.4 Community and Ecosystem Interactions

Kinds of Organism Interactions

Predation

• Interaction where one animal kills/eats another.

Predator

• The organism that eats another.

• Prey

– Animal that is eaten

– adaptation - higher reproduction rate.

Competition

Competition

• Interaction where two organisms strive to obtain the same limited resource.

Intra specific competition

• Competition between members of same species.

Inter specific competition

• Competition between members of different species.

Competition

Competitive exclusion principle

• No two species can occupy

–

The same ecological niche – In the same place

– At the same time.

• Less-fit species must

evolve into a slightly

different niche.

Symbiotic Relationships

Symbiosis

• A close, long-lasting, physical relationship between two different species.

• At least one species derives benefit from the interaction.

There are three categories of symbiotic relationships:

• Parasitism

• Commensalism

• Mutualism


Parasitism

• Relationship where one organism (parasite) lives in or on another organism (host), fromwhich it derives nourishment.

• Ectoparasites live on the host’s surface.

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– Fleas, lice, molds, mildews

• Endoparasites live inside the body of the host.

– Tapeworms, malaria parasites, bacteria, fungi




Commensalism

• Relationship where one organism benefits while the other is not affected.

• Remoras and sharks


Mutualism

• Relationship where both species benefit.

• The relationship is obligatory in many cases

– Neither can exist without the other.

Symbiotic Relationships• Examples of Mutualism

– Mycorrhizae (nitrogen fixer)

– Oxpecker and impala

Hard to Classify Relationships

Mosquito & tick

• Need blood but don’t kill, eat, or live on the host

Cuckoos

• Lay eggs in the nest of other birds

• Nest parasitism or brood parasitism

Human Niche

Varies in different parts of the world• Predator, Herbivore, Scavenger

• Commensalism

– Many organisms use our homes as places to live without affecting us

• Parasitism

– Blood drawn from cows and mixed

with milk

• Mutualism

– Domestic animals & pets

Community and Ecosystem Interactions

Community

• All interacting species of organisms in an area. Ecosystem

• A defined space in which interactions take place between a community

• Includes:

– All its complex interrelationships

– The physical environment.

Major Roles of Organisms in Ecosystems

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Three broad categories

• 1st – Producers:

– Use sources of energy to make complex organic molecules from simple inorganicsubstances in their environment.

– Usually the Sun

– Can be chemical

– Plants, algae, phytoplankton


• 2nd – Consumers:

– Require organic matter as a source of food

– Use for energy and organic molecules necessary for growth and survival

– Consumers divided into categories based

–The things they eat

–The way they obtain food


– Three consumer categories:

–Primary consumers

»Herbivores - eat plants as a source of food.

–Secondary consumers

»Carnivores - animals that eat other animals.

–Omnivores

»Consume both plants and animals.


• 3rd – Decomposers:

– Use nonliving organic matter as a source of energy and raw materials to build theirbodies.

–Many small animals

–Bacteria –Fungi

Keystone Species

Keystone species

• Plays a critical role in the maintenance of specific ecosystems.

Energy Flow Through Ecosystems

Trophic levels

• Each step in the flow of energy through an ecosystem

Second law of thermodynamics

• Whenever energy is converted from one form to another, some of the energy isconverted to a non-useful form (typically, low-quality heat)

– As energy moves from one trophic level to the next

– 90 % of useful energy is lost as heat (second law of thermodynamics).


Biomass

• Weight of living material

• Difficult to measure the amount of energy contained in each trophic level

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– Use biomass as a rough measure


Figure 05_26

Food Chains and Food Webs

Food chain

• A series of organisms occupying different trophic levels

– A result of one organism consuming another

• Some chains rely on detritus

– Particles of fecal waste or decomposing plans/animals


Food web

• A series of multiple, overlapping food chains.

• Single predator can have multiple prey species at the same time.


Nutrient Cycles in Ecosystems—Biogeochemical Cycles

Organisms are composed of molecules and atoms

• Cycled between living and non-living portions of an ecosystem.

These nutrient cycles are called Biogeochemical cycles

• Bio – living organisms

• Geo – physical environment

• Chemical – specific atoms and molecules

Carbon Cycle

Carbon and oxygen combine to form carbon dioxide

Producers (Plants) use carbon dioxide during photosynthesis to produce sugars

• Use sunlight to combine CO2 and H2O into sugar• Use sugars for plant growth

Carbon Cycle

Consumers (Herbivores & Carnivores)

• Eat plants or other animals that eat plants

• Break down the complex organic molecules into simpler molecular building blocks

• Incorporate those molecules into their structure.

• Respiration breaks down organic molecules into

– CO2 and H2O

– Releases compounds back into the atmosphere.

Carbon Cycle

Decomposers feed on organic molecules of dead

• Produce CO2 through respiration

• Recycles naturally occurring organic molecules.

Carbon Cycle

Burning fossil fuels

• Takes carbon atoms that were removed temporarily from the active, short-term carboncycle

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• Reintroduces them into the active cycle

Carbon Cycle

Carbon Cycle

Nitrogen Cycle

The cycling of nitrogen atoms between abiotic and biotic ecosystem components.

• Producers are unable to use atmospheric N.

• Must get nitrate (–NO3) or ammonia (NH3.)

Nitrogen Cycle

Nitrogen-fixing bacteria convert nitrogen gas N2 into ammonia.

• Plants construct organic molecules.

– Eaten by animals.

Decomposers also break down nitrogen-containing molecules, releasing ammonia.

Nitrogen Cycle

Nitrifying bacteria

• Convert ammonia to nitrite• Can be converted to nitrate.

Denitrifying bacteria

• Able (under anaerobic conditions) to covert nitrite to nitrogen gas (N2)

• Ultimately released into the atmosphere.

Nitrogen Cycle

Nitrogen Cycle

Phosphorus Cycle

Phosphorus is not present in the atmosphere as a gas.

• The ultimate source is rock.

• Phosphorus compounds are released by erosion

– Become dissolved in water.

• Plants use phosphorus to construct necessary molecules.

– DNA, cell membranes, ATP

Phosphorus Cycle

• Animals gain phosphorus when they consume plants or other animals.

• Decomposers recycle phosphorus compounds back into the soil.

Phosphorus Cycle

Phosphorus Cycle

Human Impact on Nutrient Cycles

Burning of fossil fuels• Releases large amounts of carbon dioxide into atmosphere.

• Increases amount of nitrogen available to plants.

Converting forests (long-term carbon storage) to agricultural land (short-term carbonstorage)

• Increased amount of carbon dioxide in atmosphere.

Human Impact on Nutrient Cycles

Nitrogen or phosphorus is applied as fertilizer

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unit 3 ppt - chap 5b - interactions

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