Ants and Acacia Trees by Alejandro Ruiz on Prezi
Every month we showcase a relationship between two or more One example of the ant-Acacia mutualism takes place in the African savanna. to it. There are over species of acacia trees. Picture of acacia trees and ants. Ants Symbiosis relationship between ants and acacia. Acacia nectar makes ants chemically dependent on the sugar of the same trees relationships among some species going, even when one partner is clearly There are other examples where two-way partnerships are more.
The acacia also provides shelter, the so-called domatia, in the hollows of its swollen thorns. Scientists at the Max Planck Institute for Chemical Ecology have now looked more deeply into the insect-plant interaction, asking whether the tiny bodyguards also provide protection against microbial pathogens.
They compared the leaves of acacia plants which were inhabited by either mutualistic or parasitic ants to leaves from which ants had been removed.
Relationship Between Acacia Tree and Ants
Intriguingly, the leaves of acacia colonized by parasitic ants showed more leaf damage from herbivores and microbial pathogens than did the leaves that had mutualistic ants. Analysis of the surfaces of the leaves revealed that the number of plant pathogens as well as of necrotic plant tissues increased considerably when mutualistic Pseudomyrmex ferrugineus ants were absent.
These plants also showed strong immune responses in the form of an increased concentration of salicylic acid, a plant hormone which regulates defence against pathogens. Detailed analysis of the bacterial composition on the surfaces of the leaves suggested that the presence of mutualistic ants changed the bacterial populations and reduced harmful pathogens.
Symbiosis -- Defensive Examples
Although far less pronounced, this effect could also be observed in parasitic ants. Food The acacia gives the necessary nourishment to the ants which live on it, as it provides them with: Beltian Bodies The Beltian bodies are red in color, and are found on the tips of the leaflets of acacia. The Beltian bodies are a great source of nutrients as they are rich in: Proteins Lipids It is believed that the Beltian bodies were developed as a result of the relationship between the ants and the acacia tree, which implies that the tree produces the nutrient-rich bodies only to feed the ants.
Nectar Nectaries are found towards the base of the petioles of the acacia tree. The ants feed on the sweet carbohydrate-rich nectar secreted by the nectaries, and gain the energy that they require to sustain their lives. How is the Acacia Tree Benefited In return for the food and shelter that the acacia provides, the ants protect it.
This can be studied in three parts: Protection Against Insects The ants do not harm the acacia tree, but there are several insects which might harm wither the leaves, rot the flowers, etc. The ants ward off all other insects which try to occupy the acacia, thus protecting the tree from any damage. Defense Against Herbivores Apart from the insects, the acacia also faces a threat from herbivores.
The ants protect the tree from herbivores too.
Ants protect acacia plants against pathogens
When the herbivores try to eat the leaves of the acacia, they cause the branches of the tree to move, this acts as a signal to the ants living in the domatia. The ants quickly reach the herbivore who is trying consume the leaves, and start stinging it.
Under these conditions, the plants cut back on the amount of sugar they provide to the ants, whose services are not as important without the herbivory occurring.
Deprived of this sugar source the ants turn to another - they allow sap-sucking insects such as aphids or scale insects to attach to the plant and then get sugar exuding from the sap-suckers This ant-aphid symbiosis is common in the ant world - many species of ants do this, and they protect the aphids or scale insects from predators in return. Thus, the plant goes from having the ants as an ally to having the ant as an enemy. Ironically, it was this type of ant that was first co-opted by the acacias when they started producing nectaries and thus inducing the ants to abandon their sap-sucking proxies and go to work full-time for the tree.
The classic line is that the ants drive away all insects and other invertebrates from the Acacia.
Relationship Between Acacia Tree and Ants
They also deter vertebrate herbivores from chewing on the leaves, and even cut away epihytic plants. In some cases they may come down from the Acacia tree and remove or kill by girdling competing vegetation in the immediate vicinity.
Our observations in Costa Rica showed that the ants don't exclude all insects and other animals from the Acacia.
To the left, a spider is spinning its web adjacent to an inhabited thorn. This beetle was crawling around on an Acacia leaf, of course it is possible that it would be run off or killed in short order. This praying mantis was doing its preying on an Acacia, apparently with little interference from the ants. Of course, having a preying mantis on the plant is good from the Acacia's point of view, but how do the ants know which insects to allow and which to drive off?
Perhaps there is a questionnaire Vertebrates sometimes make their homes in Acacia trees as well.
Bird nests in Acacias are not bothered by many of the traditional nest predators snakesbut how the birds themselves avoid the ants isn't clear.