Relationship Between Acacia Tree and Ants
Myrmecophytes are plants which live in a symbiotic relationship with ants. The acacia species Acacia hindsii, which is native to tropical dry. Ants and Trees: A Lifelong Relationship. An American carpenter ant licks sugary nectar off the surface on an oak gall. Credit: Aaron M. Ellison. The relationship between acacia and ants is an example of mutualism. The following ScienceStruck article discusses the acacia-ant connection in detail.
The ants hollow out the thorns and thrive in them. Such a shelter is also called domatia. As they live in the thorns, the ants are protected from difficult climatic conditions. 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 evolutionary history of symbioses between tropical ants and their plant hosts
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. 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. After some resistance, the herbivore gives up, and leaves the tree alone. In addition to this, the ants also eliminate any plants that try to grow on, or near the acacia, hence the acacia does not need to compete for resources. Special Features of the Acacia-Ant Relationship The relationship between the acacia and the ant is characterized by the interesting features mentioned below: It's a good deal for both the trees and the ants.
So, we know that ants defend leaves, and leaves are most important to trees when conditions are dry. Scientists then asked, is leaf defense by ants better when trees live in dry places?
To answer this question, the scientists looked at trees and ants in dry places and wet places. In all these places, they measured how good the ants were at defending their tree home. Ants defended leaves better under drier conditions. This means that trees survive more in dry places because their ants protect their food supply.
Ants and Trees: A Lifelong Relationship - American Forests
This is a perfect deal for trees. But, the scientists wondered, can the trees actually encourage their ants to be better defenders when conditions are dry?Amazing Symbiosis: Ant Army Defends Tree - National Geographic
Ever heard of a scale insect? These weird little insects are like plant vampires. The sugars that plants make in photosynthesis move around the plant as sap in special tubes. The scale insects insert their mouths into these tubes and suck the sap.
Insects are animals, and like all animals, they use some of what they eat to grow and make babies, and they poop out the rest. Plant sap has more sugar than the scale insects can use, so scale insects poop sugar. This makes them a favorite of ants, which can't drink plant sap straight from the plant, but love sugar.
That's right, the ants eat the sugary poop from the scale insects. When ants live inside trees, they often have herds of these sugar-pooping scale insects.
It's a lot like people having herds of cows for milk. We can move our cows around a pasture, but the amount of milk we'll get depends on how much grass is growing in the pasture. In the same way, the ants can move their scale insects around the tree, but the amount of sugar that the ants get depends on the tree.
Trees Trade in Sugar The scientists found that trees in drier places had more scale insects for ants. Does the tree provide more food for ants in drier places to get better defense for their valuable leaves? The scientists answered this question by using math to ask what the trees should do with their sugar under different conditions.
They found that trees at drier sites should provide more sugary food to defending ants to avoid losing leaves and dying from starvation. Trees at wetter sites should use their sugars for growth instead of giving them away to the ants. Ants tending their scale insects. Much like keeping a heard of cows, these ants keep scale insects for their sugar poop that they use for food.
Ant Insurance If your parents have a car, they buy car insurance. They have to pay a small amount of money every year to the insurance company. If the car is damaged in an accident, it may be very expensive to fix it. But because your parents have car insurance, the insurance company pays the bill.
Trees Get By with Ant Aides
The scientists reasoned that a similar thing was happening with trees and ants. Trees that live in very dry places have more scale insects to get sugar out of the trees to pay the ants. Ants then do a great job of defending the leaves in the rainy season, so that the tree has enough food to survive the next dry season. And the bills are paid in sugar. These two graphs are from the original article. They tell part of the story of how ants and trees work together.
Click on the graphs to enlarge and to learn more about them. Additional images by L.