UNSW scientists suspect that New Guinea's bronze quoll could be a long lost Aussie that was isolated in New Guinea when climate change caused a rise in sea level.
Eighteen thousand years ago and for 90 percent of the last 250,000 years, Australia and New Guinea shared a land bridge that allowed animals and people free passage in both directions.
But 6,000 to 8,000 years ago, warmer temperatures, glacial melting and rising seas closed the land bridge, effectively "stranding" a colony of Australian western quolls across Torres Strait on the mountainous island of New Guinea.
Now, new genetic research by UNSW biologists Karen Firestone and Steve Hamilton reveal that the bronze and western quolls may be the same creature. The two marsupials share 98 per cent of some parts of their DNA in common and are more similar genetically than any of Australia's four quoll species (the western, northern, eastern and spotted-tail).
"It's preliminary finding supported by Firestone's and other scientists work but comparative similarities suggest that the two species share a relatively recent common ancestry," says PhD student Steve Hamilton, who recently returned from the TransFly Savannas of Southern New Guinea where he made a six-month study of quolls.
"Genetically, the two species show a striking similarity in parts of their 'mitochondrial DNA'," says UNSW's Karen Firestone, a quoll expert who has made several study tours of New Guinea. "This region of the genome is a non-coding DNA sequence commonly used as a genetic landmark for DNA comparisons."
Discovered in 1979, the New Guinean bronze quoll was first thought to be an isolated population of the western quoll. About the size of a small cat, the animal has a rust coloured pelt with white spots, weighs up to 1.3kg and measures 70cms when fully grown. In 1988 the animal was classified as a distinct species, based on differences in skull size and other body differences.
Australian western quolls - which are brown coloured, with conspicuous white spots - once occurred across 80 percent of the continent. Today, they survive only in the far southwest of Western Australia, living in jarrah forests, drier woodlands and mallee scrub.
Until now, the little that is known about bronze quolls has come from just five specimens held by different museums around the world.
However, the latest findings are based on tissue samples (ear biopsies) the UNSW scientists took from 14 additional bronze quolls. The fleet-footed creatures are notoriously difficult to observe and trap in the wild.
Hamilton and Firestone caught the elusive animals with novel lightweight traps and help from local tribesmen, who rely on hunting and farming skills for food.
"We relied on the knowledge and support of the local people to collect samples," says Steve Hamilton, who says there are still folklore stories among the villagers about the time when it was possible to walk across the land bridge that once connected New Guinea to Australia.
New Guinea: a time capsule of Australia's past
Scientists believe marsupials diverged from mammals in North America around 90 million years ago, and later made their way to Australia when it was part of Gondwana, the super-continent that included Antarctica, Africa, South America, New Zealand and New Guinea.
After much of Gondwana had broken apart, Australia began drifting northward until it collided 15 million years ago with the Pacific Plate that created the new geological land of New Guinea.
This newly formed land bridge allowed a "time capsule" of Australian marsupials and other flora and fauna to colonise New Guinea.
As Australia continued drifting northward, it pushed up what are now the New Guinean highlands. This eventually created a "rain shadow" effect that caused the dry weather conditions we still experience in Australia today.
Over time, many of Australia's plants and animals evolved or died out in response to the warmer drier conditions, which is why New Guinea's flora and fauna are like a snapshot of the past.
According to Steve Hamilton, the region is one of the most distinctive eco-regions in Australasia because of its blend of Australian and New Guinea species and its mosaic of dry savannas, interspersed with monsoon forest and extensive wetlands.
"There are at least 51 mammals found just across Torres Strait in the TransFly Savannas of Southern New Guinea that can also be found in Northern Australia," he says.
These include agile wallabies, northern brown bandicoots, short-beaked echidnas, red-legged pademelons, spectacled-hare wallabies, red-cheeked dunnart, brush-tailed rabbit rats, Cape York rats, water rats, sugar gliders, little red flying foxes and a number of other bat species.
"We also encountered some less commonly encountered species that haven't been seen for 50 years and others that had never been reported from that part of New Guinea.
"We're still examining material that may prove that some mammals in this area are uniquely different from those in the rest of New Guinea and Australia," says Hamilton.
Geography and habitat
The TransFly region encompasses 76,000 square kilometres at the southern tip of the islands of New Guinea. It lies below the area bounded by the mouths of the Fly River in the east to the Digul River in the west.
The region includes four major types of habitat: forests (rainforest and monsoon forest), savanna-woodland (including grassland), freshwater (streams, lakes and swamps) and mangroves (brackish water).
Some of the largest and healthiest wetlands in the Asia-Pacific are found here, thriving in an area sparsely settled by humans but actively used by countless species. Millions of birds inhabit the floodplains of the region's many rivers and the surrounding savannas and monsoon forests are home to endemic quolls, flying possums and birds of paradise.
Scientists have identified 102 species of reptiles, including nine turtles, two crocodiles, 52 lizards, and 39 snakes. More than 50 percent of New Guinea's bird population is found here, and 25 species of frogs have been identified. The region contains over 60 distinct cultural groups, whose lives, customs, languages and knowledge are linked inextricably with the landscapes of the TransFly.
Quoll love potions
People who live in traditional cultures have long held to the idea that consuming certain plant and animal extracts can impart magical, restorative and curative properties. So it is in the TransFly where UNSW scientist, Dr Karen Firestone, met a tribal elder who subscribed to the belief that quolls can improve one's romantic prospects. "I met an elderly man in a village who told me about the traditional belief that burned and crushed quoll bones, when made into a paste and daubed on the forehead, was a kind of 'love potion' that improved one's chances of finding a mate!"
According to PhD student Steve Hamilton, the thick woodland in large parts of the TransFly means that villages that are no more than 30 to 50 kilometres apart have little contact with one another. This has allowed distinct traditions and languages to develop. Individual villages are subdivided into clans, each identified by its own animal name. According to tradition, men can only marry a woman from a neighbouring village (to a narrow gene pool) and must be able to "donate" a female of own family to a neighbouring village in return. While people from the TransFly region sometimes wear traditional dress they also have a high command of English.
Yams, taros, sago, coconuts, bananas, wallaby and deer were frequent menu items for the visiting scientists. "The food really was fantastic," says Dr Firestone. "We ate very well the whole time we were in the field." The TransFly region has well defined wet and dry seasons that produce major contrasts in the landscape and people's lifestyle. The December to March wet season brings heavy rains that swell rivers and inundate floodplains so that canoe is the only viable means of transport. Farming is impossible during this time so the locals protect their food supply by storing it in specially built tall structures such as a 'Yam house'.