Ecology

YOU ARE LEARNING:

Interdependence

Organisms rely on one another for food, shelter, and reproduction. Interdependence is vital for a stable community, and if one species is removed from a community, those that were relying on it may suffer.

A stable ecosystem is a series of interactions between all the organisms in that area and their environment. For example, an apple tree needs insects. What does it need them for?

$\text{insects} \iff \text{Elderberry bush} \iff \text{birds}$ The elderberry is a common hedgerow species, but it can only exist with the help of birds and insects. Birds and insects need the elderberry bush to survive too. What do you think the elderberry bush need the birds for?

$\text{insects} \iff \text{Elderberry bush} \iff \text{birds}$ In this relationship, the insects gain shelter and they collect food from the bush's flowers which produce sugar rich nectar. What does the bush gain from the insects, though?

Many plants use insects as pollinators and provide nectar in return. They may also provide shelter. Plants also need to disperse their seeds. Some do this by producing fruits that are full of sugar.

How does a blackbird help disperse the seeds of the elderberry bush?

The acacia tree that grows in Africa has sharp spines to stop animals eating it, but this is no use on caterpillars etc. The tree also has round hollow galls on its branches. These galls are full of biting ants that produce formic acid. These ants eat the other insects to protect the tree. What's in it for the ants?

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$Grass \rightarrow rabbits \rightarrow foxes$

What do the foxes gain from the rabbits?

What does the rabbit population gain from the foxes?

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These complex interdependent relationships help to maintain healthy population sizes in an ecosystem. Reducing or removing any one population can be devastating to the entire ecosystem!

The elderberry bush is at the centre of a series of relationships that benefit both the bush and other organisms in its ecosystem.

These bushes form part of the ancient hedgerows in the UK countryside. They are removed by developers to make way for new homes.

What will this removal of a single species do to the other populations that are linked to it in these ecosystems?

A) They will decline. B) They will go extinct. C) They will be unaffected.