Topic 6 ecology

Organisms and their environment:

An organisms environment is everything living and nonliving that surrounds an organism.

Describe your environment:

Parts of an ecosystem:an ecosystem is made up of all

living things that interact with one another.Interacting living things are termed biotic factors

When scientist study ecosystem they also study non-living things such as soil.Non-living parts of an ecosystem are termed abiotic factors

Abiotic factors include things like rainfall, acidity, temperature,and amount of light.

Environmental limits on population size

Living things could produce populations of infinite size if resources were infinite.

Limiting factors in an ecosystem:oxygenwater amount, pH and temperaturecarbon dioxidenutrientsspaceSunlight and temperature

All of these are finite resources. That means that they will run out.This creates competition among organisms for the resources.The populations will overpopulate an area and then die off, creating a stable population.

Populations are also controlled by Pedator-prey relationships.

The number of organisms of a single species that an ecosystem can support is referred to as it carrying capacity. This is determined by both the biotic and abiotic factors in the ecosystem

Hw Questions 1-9

Population interactions• Most interactions happen as organisms obtain food.•Every population is linked directly or indirectly•Each population has one or more specific roles in the ecosystem

Roles in the Ecosystem:•The role that each species plays in an ecosystem is called its ecological niche.•Only one species at a time can occupy a particular niche. More than one ends up with competition among the species.

Competition for a particular ecological niche happen when foreign species enter an area.•Zebra muscles– brought to great lakes. Eat all the natural food and overpower natural species.•Purple loosestife takes habitat of the native cattail•Eurasian milfoil•Non-native ladybug species.

• Purple loosestife takes habitat of the native cattail

• Eurasian milfoilTAKES UP SPACE AND NUTRIENTS FOR NATURAL WATER PLANTS

•Non-native ladybug species.

NO NATURAL PREDATORS

Emerald ash borer

DESTRUCTION OF BLACK ASH TREES

Relationships in an ecosystem:

In every ecosystem ,populations are linked together in complex webs of interactionsSome relationships are competitive

fight for same resourcesSome relationships are co-operative

whale and feeder fishSome relationships are predator-preySome relationships are parasitic

Food ChainsIllustrate the relationships between predators and prey The arrows indicate the direction the energy flows.

All energy originally comes from the sun.

Autotrophs or producers turn the sun energy into foodHeterotrophs or consumers get their energy by consuming other organisms.

Three types of heterotrophsherbivores-eat only plantsCarnivores – eat only meatOmnivores- eat both plants and animals

Decomposers recycle materials that can then be used by producers.

Other types of relationships that exist: Scavengers and Parasite/Host

Food webs: these show the inter connected food chains

Hw:Questions 10-27

Energy Flow Through an Ecosystem

Solar energy is the primary energy source for most living things in our biosphere. This solar energy is first captured by producers.

Primary consumers get their energy from the producers they eat.

Secondary consumers get their energy from their prey, etc, etc.

A lot of that energy is lost as heat from the organismsThis means that each link in a food chain has less energy available to use for itself.

If we use a box to represent the energy available in each link of the food chain and stack them starting with the producers at the bottom, we

create an energy pyramid.

SecondaryConsumers

Grass

Eagle

Snake

Cricket

Food Chain

Producers

PrimaryConsumers

Energy Pyramid

Tertiary Consumers

Recycling and Reusing

Every last bit of the energy stored in an organism’s body gets used.

Decomposers get whatever energy that’s left in a dead organism,

but they also make sure that the raw materials that made up the organism’s

body are returned to the soil so that producers can start the process all over

again.

It may seem kind of gross to you, but think about all the organisms that survive by breaking down dead organisms.

These are the decomposers (some bacteria, fungi, worms, etc) and they fill a

vital role in any ecosystem.Without raw materials being returned to

the soil, producers can’t survive.What would happen to the energy pyramid

if the bottom level got too small? (Think “Jenga”)

Vital Raw Materials

As “raw materials” are taken from the environment, used, and returned, material

cycles are created.

Some of the most important material cycles are listed below:

Water

Carbon

Nitrogen

Phosphorous

Homework: (#28-39)

The decomposers play important roles in most of these cycles.

Without them, the ecosystem would eventually collapse.

Diversity in an Ecosystem

Our biosphere, Earth, is made up of many different ecosystems. Each with

it’s own special characteristics.

Organisms with adaptations that allow it to survive in an ecosystem

play a special role in that ecosystem. They fill a niche.

If a niche is left unfilled, the ecosystem would be thrown out of balance, affecting every

organism living in it.The resulting variety of organisms that

evolved in each niche is called biodiversity.

The greater the biodiversity of an ecosystem, the more stable the ecosystem is.If something catastrophic happened to one species, another may be able to fill it’s niche and balance the ecosystem again.

Factors Affecting Biodiversity

Biodiversity can be lost due to a number of factors, some natural, and some man-made.

Habitat destruction, for whatever reason, can alter an ecosystem forever. Although some organisms may be able to eventually return

to an area devastated by a disaster, organisms that filled critical niches might never return.

If the interdependence of the organisms in the ecosystem is too great, this loss of biodiversity can ensure that the ecosystem never

returns to it’s original state.

The Human Factor

Besides human-caused habitat destruction, humans also contribute to the loss of species in several other ways, direct and

indirect.

Examples:Removal/killing of predatory species.

1) Removal of natural predators allows prey species populations to explode.

2) Overpopulation of the prey species results in drastic reductions of their food supply through overgrazing. Mass starvation occurs.

3) Overgrazing destabilizes the soil, allowing erosion of soil…even fewer plants…more starvation…fewer species…

Another Example:Agriculture

1) Farmers grow hundreds of acres of one type of crop.

2) The crop is in constant danger from disease and pests.

3) This man-made loss of biodiversity sets the stage for severe environmental disruption.

In nature, biodiversity ensures that no single food source is concentrated in that way. This makes it more difficult for any single type of pest or disease to disrupt the ecosystem.

Biodiversity is also extremely important as a resource.Genetic material in various organisms is useful in making new medicines, insecticides, etc.

Homework: Pages 111-112 (#40-45)

Pages 112-113 Environmental Changes

Ecological successionIn any ecosystem, all organisms living within it interact with biotic and abiotic factors.In this way, communities change their environment.

As the environment changes, some communities may have trouble adapting while others may thrive. The communities may also change as a result.This change of habitat from one type to another is called ecological succession.

Example:Grass grows in simple soil, but creates deeper, richer soil when it decomposes.The deeper, richer soil can support larger plants like shrubs and bushes. Grasses decline.Shrubs and bushes make soil suitable for trees.Trees replace them.

Pioneer Organism

Bare Rock

Pebbles Simple Soil

Pebbles

Acted upon by

Produces

Lichen

Moss

SoilGrasse

sBetter

Soil

Better Soil

Bushes Fertile Soil

Fertile Soil

Trees ForestClimax Community

Can a pond or lake ever become a forest?The simple answer is “YES”.

HOW?

Homework: Pages 114-115 (#46-59)