Tiny frogs face a troubled future in New Guinea’s tropical mountains


Paul Oliver, Australian National University and Mike Lee, Flinders University

At night, the mountain forests of New Guinea come alive with weird buzzing and beeping calls made by tiny frogs, some no bigger than your little fingernail. The Conversation

These little amphibians – in the genus Choerophryne – would shrivel and dry up in mere minutes in the hot sun, so they are most common in the rainy, cooler mountains.

Yet many isolated peaks, especially along northern New Guinea, have their own local species of these frogs.

So how did localised and distinctive species of these tiny frogs come to be on these isolated peaks, separated from each other by hotter, drier and rather inhospitable lowlands?

Our new study of their DNA, published this week in the open access journal PeerJ, reveals how they achieved this feat. It reveals a dynamic past, and more worryingly it highlights the future vulnerability of tropical mountain forests and their rich biodiversity.

A hotspot of frog diversity

New Guinea has an astounding diversity of frogs: more than 450 known species and counting. This is nearly double the diversity in Australia, a landmass ten times larger.

Remarkably, a majority of these species are in a single species-rich, ecologically diverse group that have dispensed with the tadpole stage.

Instead they hatch out of their eggs as tiny little replicas of the adults. Because they do not depend on still pools of water to breed, they do really well in the incredibly wet, but steep mountains of New Guinea.

One of our group (Stephen Richards) has been collecting DNA from frogs across New Guinea for the past 20 years. This work is at times arduous and painful. Having a leech worm its way into the back of one’s eye, and then stay there for more than a week, is not pleasant.

But these trips are also extremely rewarding. So far we have described more than 70 new species, and discovered many more that await description.

They also provide opportunities to explore some of world’s most wild places. Perhaps the best example is the first scientific expedition to the remote Foja Mountains.

This isolated mountain range in northern New Guinea was previously almost unexplored, but revealed a treasure trove of diversity, including a “lost” bird of paradise, a completely new species of another bird, and a bizarre treefrog with an erectile nose.

We also found several species of Choerophryne frog. DNA from these allowed our team to test two potential ways that miniature frogs could have come to occupy distant mountain peaks that are separated by inhospitable lowlands.

Across the Fojas by frog

The first way involves mountain-top frogs evolving separately on each isolated peak, potentially from larger frogs capable of surviving in the hotter and drier, nearby lowlands.

If this were the case, the frog on any given mountaintop would be most genetically similar to frogs from adjoining lowlands.

The other way involves exploiting climate change. During past phases of global cooling (glacial periods), the colder, wetter, mountainous habitats of New Guinea expanded downhill, a process termed elevational depression.

If depression was extensive enough, the frogs on one mountain might have been able to travel across tracts of cool, wet lowlands to colonise other mountains.

Later, a warming climate would wipe out the lowland populations, leaving two isolated mountain populations, which might eventually become new species.

If this were the case, we would expect the frogs in different mountains to be genetically related, since they almost literally hopped from one peak to the other.

Our new study of the DNA of the little Choerophryne frogs indicates they used both routes to conquer the peaks of New Guinea.

In the remote Foja mountains, for example, there are three species of Choerophryne. One species has evolved in situ in northern New Guinea from nearby lowland frogs.

The other two are related to frogs from distant mountains of central New Guinea, and presumably moved across the intervening lowlands during cooler glacial periods.

The little frogs and the future

Why does it matter how the tiny frogs moved to their mountain habitats? Because it could be a warning to their future survival.

Tropical mountains have some of the most biodiverse assemblages of plants and animals in the world. Their ecosystems are also far more dynamic than is popularly recognised.

Just like glaciers, the movements of frogs (and other organisms) up and down mountains has tracked global temperatures. As we’ve shown, the global cooling in past glacial periods allowed the mountain-dwelling frogs to move down across the lowlands to find new mountain peaks.

But today, as global temperatures soar to levels not seen for millions of years, their habitable cool zones are heading in the other direction: shrinking uphill.

We have no idea how quickly these frogs will respond to these changes, but recent research elsewhere in New Guinea has found birds are already shifting upslope rapidly.

We don’t yet know what could happen to these cute little amphibians should temperatures continue to climb, and they in turn run out of mountainside to climb.

It’s more than ten years since the first expeditions to the Foja Mountains, and this study provides a great demonstration of the ongoing value of the scientific data collected on these trips.

We now have a snapshot of the distinctive frogs (and many other animals) that live at the tops of these remote mountains, and a window into their past.

This provides an incredibly important resource to help us understand the dynamic history of these mountain forests, and reminds us that despite their inaccessibility, they face an uncertain future.


Stephen John Richards, a research associate in systematics, biogeography and conservation of amphibians, at The South Australian Museum, was a co-author on this article.

Paul Oliver, Postdoctoral Researcher in Biodiversity and Evolution, Australian National University and Mike Lee, Professor in Evolutionary Biology (jointly appointed with South Australian Museum), Flinders University

This article was originally published on The Conversation. Read the original article.

Argentina: Fluorescent Frog Discovered


The link below is to an article that reports on the discovery of a fluorescent frog in Argentina.

For more visit:
https://www.theguardian.com/world/2017/mar/14/worlds-first-fluorescent-frog-discovered-in-south-america

Frogs v fungus: time is running out to save seven unique species from disease


David Newell; Benjamin Scheele, James Cook University; Lee Berger, James Cook University, and Lee Skerratt, University of Melbourne

In the late 1970s in southeast Queensland, a silent killer arrived on Australian shores. The victims were our unique frogs, with the first to fall being the remarkable gastric brooding frog, last seen in 1981.

More than three decades on, we know that the killer was a disease called chytridiomycosis, caused by amphibian chytrid fungus.

This fungus is responsible for the presumed extinction of a further five Queensland frog species, and the decline and disappearances of many local populations across Australia’s entire east coast and tablelands, including species that were once widespread and common. Globally, hundreds of amphibian species have also suffered major declines or are now considered to be extinct as a result of this disease.

Scanning Electron Microscope image of infected frog skin with fungal tubes poking through skin surface.
Photo Lee Berger

In a study published in Wildlife Research, we and our colleagues identify seven more Australian frogs that are at immediate risk of extinction at the hands of chytrid fungus, including the iconic Corroboree frogs (both southern and northern species), Baw Baw frog, spotted tree frog, Kroombit tinker frog, armoured mist frog and the Tasmanian tree frog. We predict that the next few years may provide the last chance to save these species.

While the six already extinct Queensland species all declined rapidly after the arrival of chytrid, declines in southern regions have been slower. Chytrid is yet to arrive in areas of Tasmania’s Wilderness World Heritage Area, although the consequences are likely to be just as severe.

Our work aimed to prioritise frog conservation efforts across Australia, identifying the species most at risk of chytrid, and therefore most in need of urgent action. Worryingly, we found that five of the seven high-risk species that we identified lack a sustained and adequately funded monitoring program to protect them.

In addition to the seven species at immediate risk of extinction, we identified a further 22 that are at moderate to low risk. We also assessed the adequacy of current conservation efforts for all of these species, and found that most recovery efforts rely on the goodwill of individuals and are poorly resourced.

A healthy Tasmanian tree frog.
Author provided

It is possible to manage the threat posed by chytrid fungus, but rapid action is urgently needed. We have identified six critical management actions that are required to prevent further extinctions of Australian frogs and call for an independent management and research fund to address the imminent threat.

The seven species at high risk require proactive recovery programs. Critical management actions may include: broad-scale surveys; intensive monitoring; precise risk assessment; the development of husbandry techniques for the establishment of assurance colonies; re-introductions and or translocations; and new management strategies to maintain wild populations.

Australia initially led the world in efforts to identify and manage chytrid fungus, which was listed as a “key threatening process” by state and federal governments in 2002

In 2006, a plan was drawn up to combat the disease, delivering more research funding and resulting in greatly improved biosecurity measures and increased understanding of the fungus.

In 2012 the plan was reviewed, and a revised plan that incorporates recent research developments now awaits approval. But action is required to manage the impact of the fungus, and disappointingly there has been no funding allocated to implement the new plan.

Blink and you’ll miss them: the armoured mist frog (left) and waterfall frog.
Robert Puschendorf, Author provided

The past decade has also seen major cuts in both state and federal government resources for wildlife conservation. State agencies have disbanded dedicated recovery teams and there has been a shift away from single species conservation measures in an effort to maximise limited funding. This is despite the obligations set out in legislation to conserve individual threatened species. These cuts have severely undermined frog conservation efforts.

These frogs should not be allowed to go the same way as the Christmas Island pipistrelle, which could arguably have been saved if the federal government had heeded scientists’ warnings.

On a positive note, management interventions have saved the critically endangered Southern Corroboree Frog from extinction for now, but it remains threatened by chytrid fungus and requires ongoing management and research. Without swift action, government support and the dedicated efforts of many individuals, this species would undoubtedly already be gone.

The Conversation

David Newell, Lecturer, School of Environment, Science & Engineering; Benjamin Scheele, Postdoctoral Research Fellow in Ecology, James Cook University; Lee Berger, Senior Research Fellow, James Cook University, and Lee Skerratt, Principal Research Fellow, One Health Research Group, University of Melbourne

This article was originally published on The Conversation. Read the original article.