Fatal Attraction—The Loving That Leads These Marsupials to Death

Researchers from the Queensland University of Technology's (QUT) have discovered two new species of marsupials whose sexual practices often kill them off. One is already threatened with extinction thanks to habitat loss, feral pests, and climate change.

The team, led by Dr. Andrew Baker, found and named the two new Dusky Antechinus species. One type, already known on the mainland, was raised to species status and the team discovered the other new species in remote, south-eastern Tasmania. In the past three years the work of these researchers has resulted in five new species of antechinus, amounting to the genus of Australian mammals seeing an increase in diversity of 50 percent.

"We discovered the Tasman Peninsula Dusky Antechinus not far from the old European settlement town of Port Arthur in Tasmania," says Dr. Baker, a mammologist from QUT'sScience and Engineering Faculty. "Most of its limited habitat falls within state forest, which is being logged. This species now apparently only lives in tiny, fragmented stands of intact forest that are under threat."

"Uncovering new mammals in developed countries like Australia is pretty rare and the fact we've found even more antechinus species hints at the biodiversity jewels still waiting to be unearthed. It's a shame that mere moments after discovery, these little Tasmanian marsupials are threatened with extinction at human hands."

The findings were published in the journal Memoirs of the Queensland Museum - Nature.

The researchers indicate that the deadly sexual practices of the antechinus render them more vulnerable to extinction; all male antechinus fight and die for sex annually.

"The breeding period is basically two to three weeks of speed-mating, with testosterone-fueled males coupling with as many females as possible, for up to 14 hours at a time," Baker says. "Ultimately, the testosterone triggers a malfunction in the stress hormone shut-off switch; the resulting rise in stress hormones causes the males' immune systems to collapse and they all drop dead before the females give birth to a single baby. This yearly male suicide mission, which halves each antechinus population, means the mums have enough spiders and insects to eat while they raise the next precious generation. But the future of each species is entrusted to the mothers alone."

Baker also told the Australian Broadcasting Company: "They'll bleed internally, they have ulcers, their fur falls off in patches, sometimes they're stumbling around blind and still trying to mate."

Dr. Baker and his team are hoping to achieve threatened status with the Tasmanian and Australian governments for a threatened species listing for the the Black-tailed, the Silver-headed, and the Tasman Peninsula Dusky Antechinus.

"Both [the Black-tailed and the Silver-headed Antechinus] are found on remote mountaintops in south-east Queensland. They each possess perhaps the smallest distributions of any Australian mammal, just a few square kilometers. These species have already retreated to their misty mountain summits-in the face of ongoing climate warming, they have nowhere left to run."

These trends are part of a larger, disturbing pattern.

"Nine in 10 Australian mammal species are unique, yet they are vanishing before our very eyes," says Baker. "In a country with the worst mammal extinction rate anywhere on earth, Australia is in the midst of unprecedented loss of its biological treasures. Millions of native mammals likely fall victim every night to feral cats alone. Other introduced ferals, such as European foxes and poisonous cane toads, account for the deaths of millions more. These threats, together with global warming, fires and habitat loss, may cause local population extinctions of our unique mammals almost weekly."

The team hopes to secure more funding for their study on these threatened animals. Their plans include searching for more new antechinus species, mapping their actual range in the wild, and identifying protective measures.

"The risk is that these animals may disappear very rapidly," said PhD student Thomas Mutton. "For the rarest species, there may only be hundreds of individuals or less. It's very possible some of these beautiful species could go extinct. There are many species at risk in Australia and it's really something I think as a society we need to think about more deeply."