The relationships between the various elements of an ecosystem is far from idyllic; between one species to another, there are no such things as mutual respect or the selfless help. If two species there is a relationship of predation or competition for food ratio of their relationship will be based on indifference.
The survival of an individual representing the death of another: one must eat to live lynx a hare, the hare feeds on grass and so on. However, in a stable eco-system remains a constant balance between the parties that compose it.
between plant and plant are also a reflection of this daily struggle for life: a tree that grows more than the others steal the precious light on which species will lay the shadow of its branches.
In the run up to the light some species take a kind of revenge on trees, choosing not to have a trunk but to use an external carrier already is the case, for example, ivy (Hedera helix).
This 'theft' the stem is a parasitic type of relationship, not in the strict sense of the word - not the ivy sucks the sap of the tree as some believe - but because if the ivy from the tree gets a benefit, support, while ' the tree has a decrease in exchange surface area exposed to light. Ivy can get to choke an entire tree, covering it entirely by removing all the light and preventing photosynthesis until his death.
Ivy herself is a victim of a relationship that benefits only one party: its phloem sap is sucked in fact from various species aphids, due to their sharp mouthparts and sucking a bit reminiscent of 'a syringe. From the sap aphids derive a very substantial nourishment, the ivy instead suffers because of them a significant source of energy.
But not always the benefit of a relationship is to the detriment of a party: the case of so-called symbiosis in the aphid just gives us a well-known example.
On ivy that grows close to the lakes of mucille just yesterday we saw a swarm of ants were not in search of seeds or more, but busied themselves around the aphids that could find little small groups pushing aside the leaves.
The particular type of symbiosis that exists between these two insects is called 'trofobiosi' - a word that derives from the greek word for 'food'.
for aphids the ants are in fact what the cows may be for us. Aphids produce as waste products of their metabolic processes a substance of high sugary honeydew, which ants for food is a high energy intake.
The ant can induce, with a tapping of the antennae on the body dell'afide, the production by such a drop of honeydew, the ant starts licking and accumulates in the body, then regurgitate once arrived at the nest, where we retain as a reserve for the colony.
In exchange for what the aphid obtained by ants is a remarkable defensive protection from predators such as ladybird feared that by parasites that lay eggs in them such as certain types of wasps and flies. Even a
American species of ants is used to bring the aphids inside the hive during the winter months, to enable them to survive the rigors of the cold - just like a farmer who brings his animals in the stable!
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