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Gilbert’s potoroo (Potorous gilbertii)
Gilbert’s Potoroo (Potorous gilbertii) was a ratlike marsupial fungivore which lived in great numbers throughout south-west Australia—particularly around King George Sound. The animals were discovered to science by the great naturalist George Gilbert in 1840. Unfortunately the potoroo proved to be extremely vulnerable to introduced predators such as foxes and dingoes. After an exhaustive search in the 1970s failed to find any living specimens of the creature (which had not been seen in decades) the unlucky mammals were deemed extinct, and thus Gilbert’s potoroo vanished forever from the—[needle comes off of sad record]—wait! actually this strange rodent-like/kangaroo-like creature was rediscovered in 1994.
After nearly two decades during which time the potoroos were presumed dead, a small population was found living in a remote and inaccessible scrubland beside Two Peoples Bay in Western Australia. The area was proclaimed a nature preserve and humankind leapt into action to save the beleaguered potoroo.
Gilbert’s potoroo, Potorous gilbertii
Yet, it has not been easy to relaunch the peculiar animal. The creatures live on truffle-like fungi, which they dig up with their three toed paws (each digit has a sharpened digging claw). The male potoroos are susceptible to balanoposthitis, a bacterial disease which disfigures the genitals with inflammation and leaves the creatures unable to reproduce. Also the animals seem to be extremely sensitive to cryptococcosis, a dangerous fungal disease which can lead to coughing and respiratory failure.
Fortunately, patient zookeepers, rangers, and volunteers have been working to help Gilbert’s potoroo overcome these alarming hurdles. The world population now numbers nearly 70—but the peculiar marsupial digger remains one of the planet’s most endangered mammals.
Agriculture is almost unknown in the natural world. Human beings are the only vertebrates known to grow crops or keep livestock (with the possible exception of damselfish which carefully tend little algae gardens). And yet we were not the first animals to invent the concept. Ants have farmed fungi within their tunnels for tens of millions of years. Ants also keep aphids in captivity in order to “milk” them of sugary secretions–or to eat them outright. It is possible that beetles, termite, or snails came up with the concept first, but most evidence points to ants as the first farmers.
An Ant Milking Aphids
Ants do not have a shabby operation either. Leaf cutter ants form the largest and most complicated animal societies known on Earth (other than our own) and a single colony can have over 8 million individuals. Leaf cutters are an ideal example of how adept ants are at farming fungi. Four different castes of worker ants work together to bring back leaf fragments and integrate them into huge fungal gardens. Different species of leafcutters cultivate different fungi from the Lepiotaceae family. Certain bacteria with antifungicidal and antibacterial properties grow within the metapleural glands of the ants. The worker ants use these bacteria to “prune and weed” dangerous or unproductive organisms out of their gardens. Older (more expendable) worker ants carry waste products from the hive to a waste pile where they stir the hive wastes together to aid in decomposition. The waste-management job brings the danger of fungal or bacterial contamination and contaminated ants are exiled to certain death in order to keep the gardens safe. Additionally dead ants from within the hive are carefully placed around the waste pile so as to protect the hive from their decomposition.
Leaf Cutter Ants at the Cameron Currie Lab arrange cut-up leaves into their fungal garden.
According to geneticists who study the rates of mutation within the various fungal cultivars, ants began their farm relationship with fungi around 50 million years ago in the warm Eocene epoch (an era which saw many of the critical relationships in modern ecosystems begin).
Digital Cut-away of an underground leaf-cutter nest
Scientists are also beginning to understand the means by which ants herd their little flocks of aphids. The aphids are smaller insects which feed on the saps and juices of plants (which they suck out by means of specialized mouthparts called stylets). The ants prevent the aphids by flying away by tearing off their wings. The feet of the ants produce chemicals which tranquilize and subdue the aphids and keep them from escaping the “pastures” near the ant colonies. It is believed that aphids also derive certain benefits from this arrangement since the aggressive ants protect them from many of their natural predators.
An Ant with a “herd” of Aphids
For years naysayers belittled the farming achievements of ants suggesting they were little more than symbiotic arrangements. However as entomologists study the ants more carefully they increasingly discover just how complicated and sophisticated those relationships are (involving as they do numerous symbiotic relationships with bacteria in order to produce the chemicals necessary for agricultural control). Additionally, what are humankind’s relationships with our crops and animals if not huge harrowing examples of symbiosis?
ferrebeekeeper 