ecology

Ecology and the Biosphere

The Study of Ecology

Ecology

Ecology is the study of the interactions of organisms with one another and with their physical environment

Ecology comes from the Greek Word “oikos”, which means “house”

The Earth is our house. The “house” includes the environment in which organisms live, the interactions of organisms with one another, and the interaction of organisms with the nonliving environment

What is the Biosphere?

“The Living Globe”

The Biosphere is that part of the Earth in which life exists

Biosphere

Includes all land, air, and water

Extends from about 8 km above the Earth’s surface to as far as 8 km below the surface of the ocean

Living organisms are not distributed uniformly (few in polar regions and many in tropical regions)

Biosphere

Ecosystems are small ecological units

Consist of a given area’s physical features and living organisms

Nonliving Physical Features are called abiotic factors

Water, sunlight, soil type, rocks, temperature, humidity, elevation, and rainfall

Living organisms are called biotic factors

Bacteria, reptiles, fish, birds, animals, plants, and fungi

Ecosystems

All of the biotic and abiotic factors in a given area make up an ecosystem

There are many different types of ecosystems in nature…

LakeStream

Prairie Forest Wetland

All Ecosystems are Interconnected!!!!

Stream

Ecologists who study ecosystems identify the living organisms as part of a…..

Population: a collection of individuals of the same species in a given area who can breed with one another

Community: all the populations of organisms living in a given area (all of the biotic factors)

Ecologists who study ecosystems identify the living organisms as part of a…..

What Does it Mean to Succeed???

Ecological Succession

Ecological Succession

The process by which an existing community is gradually replaced by another community

Every organism affects environmental conditions around it

Ecological Succession of a Pond Community

Begins as a thriving pond community….

The pond begins to fill with organic matter like leaves, and silt, a fine soil…..


Over a period of time, the pond fills and becomes a marsh…..


Eventually the marsh becomes dry land inhabited by a stable community called a climax community


Succession often leads to a fairly stable collection of organisms

The Biomes of the World are Large Climax Communities with a Stable Collection of Characteristic Plant and Animal Life!

There are 2 types of succession that occur in nature…..

Primary Succession

Secondary Succession

•Occurs in places where no living community existed before (on a newly formed volcanic island)

•Pioneer species begin to grow

Hardy organisms that can tolerate harsh conditions

Primary Succession

• Occurs in areas where natural disasters or human activities have

wiped out an existing living community

•Pioneer species colonize the area and gradually change conditions so that they are favorable for other species

Secondary Succession

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Energy and Nutrients in the Ecosystem

Ecosystem Dynamics

All living things are made up of….

Chemical ElementsCarbon (C) Hydrogen (H)Oxygen (O)Nitrogen (N)

Chemical CompoundsWater (H2O)Glucose (C6H12O6)Proteins (CHON)

And use ENERGY!!!!!

Energy……..The ability to do work

Builds cells and tissuesGrowthReproductionResponding to environment

Energy

Ecosystem Dynamics and Energy Transfer

Energy is passed from organism to organism by feeding relationships in the ecosystem!!!

Trophic Levels

Each step in the transfer of energy in a community

•Producers•Consumers•Decomposers

Energy

Organisms that can make their own food

Autotrophs (Self-Feeding)

• Use photosynthesis to convert sunlight chemical energy• Produce carbohydrates for immediate use or storage for later

• Examples include plants, algae, and some bacteria

Producers

Animals, fungi, protists, and most bacteria that cannot make their own food

Consumers are Heterotrophs (obtain food by eating other organisms)

Types of Consumers:•Primary Consumers•Secondary Consumers•Tertiary Consumers

Consumers

Herbivore

•Eat only plants

•Primary consumers

•Deer, caterpillars, giraffes

Classification of Consumers

Carnivore

•Eat only other animals

•Secondary and tertiary consumers

•Lions, wolves, eagles, sharks


Omnivore

•Eats both plants and animals

•Can be primary, secondary, or tertiary consumer

•Raccoons, bears


Some consumers are scavengers

•Scavengers are animals that eat the flesh of dead organisms•Biological “clean-up crew”•Vultures, hyenas, crows

More About Consumers

Decomposers are organisms that obtain their energy from dead organisms

•Break down complex organic matter (decompose or decay)•Nutrients from break down of tissues are returned to the soil•Nutrients are recycled (carbon, nitrogen, phosphorus)•Bacteria, earthworms

Decomposers

Energy flows through an ecosystem. From the sun to producers to consumers to decomposers, energy powers the interactions of ecosystems.

The Flow of Energy

•Shows the flow of energy from one organism to another through each trophic level

•Energy flow is represented by an arrow

•Arrow goes in direction of energy

Food Chains

•A food web is a representation of all of the interconnected food chainsin an ecosystem

•Food webs show multiple feeding relationships

Food Web

The Food Web

Ecologists use ecological pyramids to represent the relationships among trophic levels

There are 3 types of ecological pyramids:• Pyramid of Energy• Pyramid of Biomass• Pyramid of Numbers

Ecological Pyramids

Shows total amount of incoming energy at each trophic level

The 10% rulepredicts that only 10% of the energy in one trophic level is available to the next level

Pyramid of Energy

Shows total mass of living tissue at each level

Pyramid of Biomass

Shows the total number of organisms at each trophic level

Pyramid of Numbers

Trophic Levels, Energy Flow, and Ecological Pyramids

Ecological Niche

Factors That Control Population Growth

In nature, population growth is limited to the carrying capacity of the environment

Carrying capacity is determined by a variety of limiting factors.

Population Limiting Factors

• Factors that control population growth

• Maintains population levels between extinction and overpopulation

• Two types:

• Density-dependent limiting factors

• Density-independent limiting factors

Density-Dependent Limiting Factors

• Operate only when a population is large

• Examples include:

• Competition

• Predation

• Parasitism

• Overcrowding

• Stress

Competition

Competition occurs when two or more species rely on similar

limiting resources such as space or food.

Competitive Exclusion PrincipleWhen two species are competing for the same resources, one must

– migrate to another area

– shift its feeding habits or behavior

– suffer a sharp decline in population or become extinct

Predation

One species hunts the other and uses it for food.

Predator-Prey Relationship

Parasitism

Density-Independent Limiting Factors

• Operates equally well regardless of population size

• Examples include:

• Natural disasters like volcanoes, floods, etc.

• Annual climate fluctuations

• Produces “Boom or Bust” growth curves

Relationships in Ecological Communities

Symbiosis

A relationship between 2 different species

“Living together”

3 Types:

• Parasitism

• Mutualism

• Commensalism

Parasitism

Relationship where one species benefits and the other is harmed

• 1st species (+)

• 2nd species (-)

Ex. Tick sucking blood from a dog

Mutualism

Relationship where both species benefit from their interaction

• 1st species (+)

• 2nd species (+)

Ex. Bee pollinates a flower

Commensalism

Relationship where one species benefits and the other is unaffected

• 1st species (+)

• 2nd species (0)

Ex. Cattle Egret

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