Science Focus Topic 1 Notes: Interactions Within Ecosystems | Print |

Ecology is the study of the relationship between living organisms and their environment. An ecologist is someone who studies those relationships.

The Needs of Living Things

 

Living things need a suitable habitat

Living things need food.

Living things need a suitable habitat.

Living things need water

Living things exchange gases

Living things need water.

Living things exchange gases.

Living things are always interacting with each other and with the non-living things in their environment.

Adaptations

Living things are adapted, so they 'fit' into their surroundings, to ensure survival. An adaptation is an inheritedlearned during the organism's lifetime. characterisitic that helps an organism survive and reproduce in its environment. Sometimes adapations are

Ecosystems

An ecosystem is the interactions between living and non-living things in a particular environment. An ecosystem is a place where these interactions occur, such as a rotting log, or a forest. All organisms and parts within this place are interacting all the time and adjustments must occur if the organism is to survive. Ecosystems vary in size and complexity. In order to study an entire ecosystem, scientists often study only a small aspect of an ecosystem and then work with other scientists to piece together the overall picture of how the ecosystem functions.

Interactions in Ecosystems

Symbiosis - When two species live cosely together in a relationship that lasts over time symbiosis occurs.

There are three forms of symbiosis:

Mutualism

Mutualism occurs when there is a relationship between two different organisms, in which each partner benefits from the relationship. Examples include:

 

Mutualism
between plants and their herbivores.

Anemone fish (Clown Fish)
dwell among the tentacles of Tropical Sea Anemones
Both partners benefit from the relationship,

3-way Mutualism between an ant, a butterfly caterpillar, and an acacia plant.

Parasitism

Parasitism occurs when there is a relationship between two different organisms, in which one partner benefits from the relationship, while the other parner is harmed. Typically, the partner that benefits (the parasite), lives on or in the other organism (the host) and feeds on it. Examples include:

 

Aphid mummy - the result of parasitism

A Kalahari barking gecko is crucified by a Shrik.
They store them as a cache for a later meal.

Commensalism

Commensalism occurs when there is a relationship between two different organisms, in which one partner benefits from the relationship, while the other neither benefits, nor is harmed. An example is:

An orchid plant will attach itself high up a tree trunk to have a safe, sheltered place to grow and receive water dripping down the tree trunk .

The tree trunk which provides the habitat for the orchid seems to neither be harmed nor benefit from the relationship.

Impacts on Ecosystems

Symbiotic relationships are only a few ways that organisms interact with one another within an ecosystem.
Other interactions may involve the physical changing of the ecosystem by the organisms living in it and interacting with parts of it. Like when a family of beavers make a dam, the stream below the dam dries up, killing the water organisms that need the water to survive. Above the dam, a pond changes the habitat and limits the kinds of organisms that can survive there. For every action in an ecosystem there is a resulting effect and reaction which will change the make-up of the ecosystem in some way.

Topic Review p. 17