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Suzie Imber, who beat 11 people to the prize, is "excited" she could "one day end up in space".

Most of the world's wild horses, such as the Australian brumby, are outside their historic native range. Andrea Harvey

Throughout history, humans have taken plants and animals with them as they travelled the world. Those that survived the journey to establish populations in the diaspora have found new opportunities as they integrate into new ecosystems.

These immigrant populations have come to be regarded as “invaders” and “aliens” that threaten pristine nature. But for many species, migration may just be a way to survive the global extinction crisis.

In our recently published study, we found that one of the Earth’s most imperilled group of species is hanging on in part thanks to introduced populations.

Megafauna - plant-eating terrestrial mammals weighing more than 100kg - have established in new and unexpected places. These “feral” populations are rewilding the world with unique and fascinating ecological functions that had been lost for thousands of years.

Today’s world of giants is only a shadow of its former glory. Around 50,000 years ago, giant kangaroos, rhino-like diprotodons, and other unimaginable animals were lost from Australia.

Read more: Giant marsupials once migrated across an Australian Ice Age landscape

Later, around 12,000 years ago, the last of the mammoths, glyptodonts, several species of horses and camels, house-sized ground sloths and other great beasts vanished from North America.

In New Zealand, a mere 800 years ago, a riot of giant flightless birds still grazed and browsed the landscape.

The loss of Earth’s largest terrestrial animals at the end of the Pleistocene was most likely caused by humans.

Sadly, even those large beasts that survived that collapse are now being lost, with 60% of today’s megafauna threatened with extinction. This threat is leading to international calls for urgent intervention to save the last of Earth’s giants.

A wilder world than we think

Formal conservation distribution maps show that much of Earth is empty of megafauna. But this is only a part of the picture.

Many megafauna are now found outside their historic native ranges. In fact, thanks to introduced populations, regional megafauna species richness is substantially higher today than at any other time during the past 10,000 years.

Megafauna have expanded beyond their historic native range to rewild the world. Number of megafauna per region, in their ‘native’ range only (a) and in their full range (b) Modified and reproduced from Lundgren et al. 2017

Worldwide introductions have increased the number of megafauna by 11% in Africa and Asia, by 33% in Europe, by 57% in North America, by 62% in South America, and by 100% in Australia.

Australia lost all of its native megafauna tens of thousands of years ago, but today has eight introduced megafauna species, including the world’s only wild population of dromedary camels.

Australia lost all of its native megafauna tens of thousands of years ago, but is now home to eight introduced species, including the world’s only population of wild dromedary camels. Remote camera trap footage from our research program shows wild brumbies, wild donkeys and wild camels sharing water sources with Australian dingoes, emus and bustards in the deserts of South Australia.

These immigrant megafauna have found critical sanctuary. Overall, 64% of introduced megafauna species are either threatened, extinct, or declining in their native ranges.

Some megafauna have survived thanks to domestication and subsequent “feralisation”, forming a bridge between the wild pre-agricultural landscapes of the early Holocene almost 10,000 years ago, to the wild post-industrial ecosystems of the Anthropocene today.

Wild cattle, for example, are descendants of the extinct aurochs. Meanwhile, the wild camels of Australia have brought back a species extinct in the wild for thousands of years. Likewise, the vast majority of the world’s wild horses and wild donkeys are feral.

There have been global calls to rewild the world, but rewilding has already been happening, often with little intention and in unexpected ways.

A small population of wild hippopotamuses has recently established in South America. The nicknamed “cocaine hippos” are the offspring of animals who escaped the abandoned hacienda of Colombian drug lord Pablo Escobar.

Colombia’s growing ‘cocaine hippo’ population is descended from animals kept at Pablo Escobar’s hacienda.

By insisting that only idealised pre-human ecosystems are worth conserving, we overlook the fact that these emerging new forms of wilderness are not only common but critical to the survival of many existing ecosystems.

Vital functions

Megafauna are Earth’s tree-breakers, wood-eaters, hole-diggers, trailblazers, wallowers, nutrient-movers, and seed-carriers. By consuming coarse, fibrous plant matter they drive nutrient cycles that enrich soils, restructure plant communities, and help other species to survive.

The wide wanderings of megafauna move nutrients uphill that would otherwise wash downstream and into the oceans. These animals can be thought of as “nutrient pumps” that help maintain soil fertility. Megafauna also sustain communities of scavengers and predators.

In North America, we have found that introduced wild donkeys, locally known as “burros”, dig wells more than a metre deep to reach groundwater. At least 31 species use these wells, and in certain conditions they become nurseries for germinating trees.

Introduced wild donkeys (burros) are engineering the Sonoran Desert, United States.

The removal of donkeys and other introduced megafauna to protect desert springs in North America and Australia seems to have led to an exuberant growth of wetland vegetation that constricted open water habitat, dried some springs, and ultimately resulted in the extinction of native fish. Ironically, land managers now simulate megafauna by manually removing vegetation.

It is likely that introduced megafauna are doing much more that remains unknown because we have yet to accept these organisms as having ecological value.

Living in a feral world

Like any other species, the presence of megafauna benefits some species while challenging others. Introduced megafauna can put huge pressure on plant communities, but this is also true of native megafauna.

Whether we consider the ecological roles of introduced species like burros and brumbies as desirable or not depends primarily on our own values. But one thing is certain: no species operates in isolation.

Although megafauna are very large, predators can have significant influence on them. In Australia, dingo packs act cooperatively to hunt wild donkeys, wild horses, wild water buffalo and wild boar. In North America, mountain lions have been shown to limit populations of wild horses in some areas of Nevada.

Visions of protected dingoes hunting introduced donkeys and Sambar deer in Australia, or protected wolves hunting introduced Oryx and horses in the American West, can give us a new perspective on conserving both native and introduced species.

Nature doesn’t stand still. Dispensing with visions of historic wilderness, and the associated brutal measures usually applied to enforce those ideals, and focusing on the wilderness that exists is both pragmatic and optimistic.

After all, in this age of mass extinction, are not all species worth conserving?

This research will be presented at the 2017 International Compassionate Conservation Conference in Sydney.

Daniel Ramp is the Director of the Centre for Compassionate Conservation (CfCC) at UTS. The CfCC collaborates with, and receives research grants from, a range of government, industry, and NGOs to work on conservation actions that address conservation problems and promote compassion for wild animals through peaceful coexistence. He is a Director of Voiceless, which is a funding partner of the Centre.

Arian Wallach, Erick Lundgren, and William Ripple do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

This is an article from I Have Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to alwayswondered@theconversation.edu.au

Why don’t hippopotamuses get cholera? Why are some animals resistant to waterborne disease? – Phil Morey

The short answer is that cholera has evolved to infect humans, not hippos. Cholera is a disease caused by a curved rod-shaped bacterium called Vibrio cholerae. The disease is characterised by a profuse diarrhoea that resembles “rice water”, and can lead to death within hours.

Transmission electron microsope image of Vibrio cholerae that has been negatively stained. Dartmouth Electron Microscope Facility via Wikipedia

Humans contract the disease from water contaminated with human sewage containing the bacteria. As cholera is a waterborne disease, it is prevalent in areas where human sanitation is lacking or less than ideal. Unlike many other diseases, it can’t be passed to us from animals, as malaria is from mosquitoes.

Once ingested by humans, the bacteria attach to the small intestine wall. There they reproduce, and prodcue a toxin called choleragen. The choleragen toxin is made up of two parts, called A and B. The B portion attaches the toxin to the cells in the intestine and the A portion chemically forces electrolytes and water from the intestinal cells themselves, thus leading to massive dehydration, diminished blood loss and ultimately death.

Vibrio cholerae, the bacteria that causes cholera, only impacts humans, and can only be transmitted to new human hosts via contaminated water. It’s likely that the disease mechanism is precisely adapted to human-specific molecules in the cell walls of our small intestine, and the molecular structure of the bacteria’s toxins.

The annotation on this 19th century medical illustration reads. ‘A young woman of Vienna, 23. The same woman one hour after the onset of cholera, and four hours before death.’ Wellcome Library, London, via Flickr/the lost gallery

Over millennia, both the disease-causing organism (pathogen) and host have been evolving counter-strategies against each other: the host to evade the pathogen, and pathogen to invade the host. These battles have led to the bacteria becoming host-specific, and now only able to infect humans.

The cholera vaccine works by taking advantage of this close host/pathogen relationship. It inhibits the action of the B portion of the cholera toxin, hence it prevents the bacteria from attaching to the intestinal wall.

Other waterborne diseases are caused by other pathogens (although the specific mechanisms or molecules involved differ). In some cases, as in cholera, the molecules required for infection are host-specific. Whilst other pathogens are not species specific, they are often associated with more closely-related species than less closely-related species. For example, foot and mouth disease affects cattle, sheep, deer and pigs, because they are all cloven-hoofed animals (Artiodatyla) and thus closely-related species.

Hippopotamuses (Hippopotamus amphibious and Choeropsis liberiensis) are more closely related to cetaceans (whales and dolphins), than humans, and therefore it is not surprising that they have different pathogens. That being said, hippopotamuses, like other animals, are likely to suffer from loose stools (dung) from time to time, whether due to other pathogens, or the quality of the huge amounts of plant material they ingest on a daily basis.

Dung is super important in hippopotamus society. Hippopotamus defecation or “dung showering” involves flicking their tail at the same time as defecating to distribute their dung far and wide, hence dung is used to mark their territory and assert dominance.

If hippopotamus dung spread a disease like cholera, it could be rapidly fatal for large populations. It is likely that the individuals affected would be removed by natural selection. Those that were resistant, or only mildly affected, would overcome the disease and live on to produce disease-resistant offspring. Over time, it is therefore likely hippopotamuses have adapted to their aquatic environments and thus rarely, if ever, become infected with waterborne diseases.

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Julie Old does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

State-owned company refused disclosure of security arrangements for Chinese plant the Bradwell nuclear station could be modelled on

The Chinese state-owned company planning a nuclear power station in Essex refused to share the security arrangements for a Chinese nuclear plant with the British authorities, it has been revealed.

Inspectors from the UK nuclear regulator visited the China General Nuclear Power Corporation (CGN) in Shenzhen earlier this year, as part of the four-year approval process for the reactor the company wants to build at Bradwell.

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My friend and colleague David Tayler, who has died aged 53, was a geographer, geologist and passionate conservationist who devoted his life to connecting people with landscapes. Through this he changed countless lives. Most of his career was spent in the Yorkshire Dales, running conservation, education and outreach projects.

Born to John, a local government worker, and his wife, Margaret (nee Tyler), a teacher, in Maidenhead, Berkshire, he attended the local comprehensive, Desborough school (now Desborough college). There, particularly on geography and geology field trips, he developed a lifelong affinity with landscapes, wildlife and botany. He never lost that early sense of joy and wonder at the natural world and a desire to inspire it in others.

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Tesla's big battery - already half complete - signals the speed of the energy transition. “This is what the future will look like,” Musk says. "And the faster we get there the better." The contrast with the Federal government, brandishing lumps of coal, could not be greater.

Polar tourism is a booming business but sea-ice experts have warned conditions in the Antarctic are becoming more unstable and unpredictable for shipping.

At Nyarugusu in the Geita district in north-west Tanzania, life is a constant struggle, one that is made infinitely harden by the absence of running water. Photographer Sameer Satchu travelled to the area and recorded these images of daily events at a medical facility, the Nyarugusu Dispensary, for Water Aid

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More than 100,000 people have fled their homes as they wait for Bali's Mount Agung to erupt.

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Cei Newydd/New Quay, Ceredigion Waterfalls flowed wide and white on to the foreshore, shedding excess water from the landscape

The steep path up to the headland was scoured to the bedrock by the recent storms, with banks of debris built up at the breaks of slope like shoals in a stream. Long grass at the margin was flattened and the turf had been peeled back from the edges of the rock by the passage of water.

Recent rain, a series of startlingly abrupt and intense showers, had made me wonder whether a walk on the coast path was a good plan – but the view northwards along the coast more than justified the risk of a soaking.

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A crystalline form of a synthetic molecule enhances the activity of microorganisms producing more methane, the main component of natural gas or biogas.

New low cost flexible panels can be printed and assembled in odd shapes and mass produced.

School student Angelina Arora experiments with alternatives for plastic bags and becomes finalist for BHP award.

The loss of ice has allowed a recent research trip to use yachts, rather than ice smashing trawlers. The reduced ice is loss of habitat to many large animals.

The first return migrations of whale sharks to Ningaloo Reef in Western Australia have been documented. While Ningaloo is protected, many areas where these giant endangered fish swim are unprotected waters.

From eggs to football jerseys, tens of millions of pounds raised could hire wildlife wardens for animal protection.