Scientific classification:
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
What does it look like? Th is ant is a slim-bodied species, with the workers measuring around
3 mm in length. They are orangey brown and have very large eyes.
Where does it live? This is an arboreal ant, and it is to be found on or around a certain species
of acacia tree that is found throughout Central America. Th e ants nest inside the large thorns
of these acacias.
A Relationship among the Thorns:
Acacia trees with their succulent little leaves are relished by a large number of herbivorous
animals from tiny insects to huge mammals. To protect their foliage from these hungry
mouths, they have evolved a number of ways to keep the leaf eaters at bay. Many acacias have
vicious-looking spines, while others have leaves packed with repellent and noxious chemicals.
Some acacias, however, have gone even further and actually depend on other animals for protection.
One such acacia, the bull’s horn acacia, has its own species of dedicated ant bodyguard.
The relationship begins when a young queen ant, newly mated, lands on the acacia looking for
a place to start a nest.
The thorns on this acacia are great little ant havens as they are bulbous
at their base and hollow. The queen, convinced by the odor of the tree that she is in the right
place, starts to nibble a hole in the tip of one of the thorns, eventually breaking through to the
cavity within. In the safety of her new nest she lays 15–20 eggs, and soon enough, these give
rise to the first generation of workers. Th e embryonic colony grows, and as it does, it expands
into more of the bulbous thorns. When the colony has exceeded around 400 individuals, the
repayment to the acacia for lodgings can begin, and the ants assume their plant-guarding role.
The ants become aggressive and do not take kindly to any creature they find trying to surreptitiously
munch the acacia’s leaves, regardless of whether it is a cricket or a goat. It doesn’t
take much to set them off.
Even the whiff of an unfamiliar odor sees the ants swarming from their thorns and toward a potential threat. Herbivorous insects are killed or chased away, and browsing mammals are stung in an around their mouth, which quickly persuades them to look elsewhere for less well-defended fodder. Apart from these active defending duties, the ants also have gardening to tend to—they leave the tree and scout around its base looking for any seedlings that would eventually compete with their acacia for light, nutrients, and water. If they do find any, they destroy them, and the ants even go so far as to prune the leaves of nearby trees so
that their host is not shaded out.
This is not the only example of a symbiotic relationship between a tree and an ant species. There are at least 100 species of ants that live in a close partnership with a plant. In return for the services provided by the ants, the plants furnish them with accommodation. The diversity of the relationships encompasses all the conceivable parts of a plant. Some plants have modified swellings on their branches and twigs,
while others have cavities within their stems and trunks or modified roots that house their insect guests.
• Some of these nests can be very small, only a few centimeters across, while others can
be large and elaborate.
• In South America, there is a tree, Duroia hirsute, which is sometimes found to dominate small areas of the rain forest, forming areas that the local people call “devil’s gardens.” Within special cavities on the tree’s trunk there are special cavities in which the ant, Myrmelachista schumanni, makes its nest. Any saplings sprouting near the host tree are attacked by the ants and stung with formic acid, which kills them, thus removing competition for their host’s resources.
• In some of these relationships, the cost of the ant’s protection can be quite expensive. Cordia trees in the Amazonian rain forest have a kind of partnership with Allomerus ants, which make their nests in modified leaves. To increase the amount of living space available to them, the ants will destroy the tree’s flower buds. The flowers die and leaves develop instead, providing the ants with more dwellings. Another type of Allomerus ant lives with the Hirtella tree in the same forests, but in this relationship, the tree has turned the tables on the greedy ants. When the tree is ready to produce flowers, the ant abodes on certain branches begin to wither and shrink, forcing the occupants to flee and leaving the tree’s flowers to develop free from attack by the ants.
• In the mangrove forests of Southeast Asia and New Guinea there lives an odd plant called Myrmecodia. The is green, spiky, small football-sized plant clings to the branch or trunk of a mangrove tree. Scuttling over its surface are numerous ants, and the odd plant is their home. Open it and an elaborate system of tunnels and chambers will be revealed. Some of these chambers are the nest’s rubbish tips, and the waste there in is used by the plant as a fertilizer, allowing it to fl ourish even though its roots will never come into contact with the soil.
• As you can see, ants have struck up some amazingly complex relationships with plants. On the whole, the two very diff erent organisms help each other, but occasionally, there are freeloaders. These stories exemplify the degree to which insects and flowering plants have become inextricably linked over millions of years. Ever since the flowering plants first appeared on earth many millions of years ago, the insects have gravitated toward them and evolved with them, resulting in the complex relationships we see today.
Nema komentara:
Objavi komentar