суббота, 8 февраля 2020 г.

Past climate safe havens now most vulnerable

The profound threat of future climate change to biodiversity demands that scientists seek ever more effective ways to identify the most vulnerable species, communities, and ecosystems.

Past climate safe havens now most vulnerable
Forecast warming threatens species in biodiversity rich regions, including the Indo–Pacific
[Credit: University of Adelaide]
In a new study, published in Nature Climate Change, an international team of scientists has shown that the most biodiverse regions on Earth are among the most vulnerable to future climate change.

By establishing global patterns of unusually extreme climate change events during Earth's history, and comparing these to 21st century patterns, the researchers were able to show that human-driven climate change will quickly erode important mechanisms that are likely to have sustained biodiversity across time.

"Our results show that the magnitude and accelerated rate of future climate change will disproportionately affect plants and animals in tropical regions and biodiversity hotspots. Worryingly, these are regions on Earth with the highest concentrations of biodiversity," says lead author Associate Professor Damien Fordham from the University Adelaide's Environment Institute.

Historically these regions have been safe havens from climate change during glacial-interglacial cycles. By providing refuge for species during periods of unfavourable global warming, these climate safe havens have shaped biodiversity by allowing older species to survive and new lineages to generate.

"Disturbingly, our research shows that more than 75% of the area of these climate safe havens will be lost in the near future due to 21st century warming," said Dr Stuart Brown from the University of Adelaide, who led the analysis.

"The future is most ominous for species in tropical oceans. Severe negative impacts on the richness of coral species and marine life they support are expected in regions such as the Indo-Pacific. This is likely to cause human hardship for communities that depend on these resources for food, employment and income."

For areas where climate safe havens are forecast to persist until the end of this century, the researchers show that temperatures are likely to exceed the acclimation capacity of many species, making them short-term hospices for biodiversity at best.

More generally the research shows that future climate change not only threaten species in polar environments, but also tropical regions, which contain particularly high biodiversity.

Author: Crispin Savage | Source: University of Adelaide [February 04, 3030]

* This article was originally published here

Save the giants, save the planet

Habitat loss, hunting, logging and climate change have put many of the world's most charismatic species at risk. A new study, led by the University of Arizona, has found that not only are larger plants and animals at higher risk of extinction, but their loss would fundamentally degrade life on earth.

Save the giants, save the planet
Protecting large plants and animals has a disproportionate positive impact on the health
of the planet and resilience to climate change [Credit: University of Arizona]
The study, published in Nature Communications, is based on computer simulations that compared the state of the natural world during the Pleistocene (a past epoch long before human-caused extinctions began), the present day, and a future world in which all large plants and animals had gone extinct.

Results showed that the continued loss of large animals alone would lead to a 44% reduction in the total amount of wild animal biomass on the planet. It would also lead to a 92% reduction in soil fertility, which underpins the ability of the earth to grow plants and sustain life.

"This research shows there are fundamental scientific principles that explain why large animals and trees matter for the health and integrity of all life on Earth," said lead author Brian Enquist, professor of ecology and evolutionary biology at the University of Arizona. "Protecting big, charismatic species does have an umbrella effect to protect the wider ecosystem."

A key reason for these results lies with the transport of nutrients. When large animals eat in one location and defecate or urinate in another, they transport nutrients, often moving them from nutrient-rich areas to other, less fertile parts of the land and oceans. Similarly, the largest trees are the most productive, and contain and stir more nutrients and carbon.

"Ecosystems with larger trees and animals are also more productive and provide more vital ecological services," Enquist said. "I use this analogy: The largest banks and corporations in the economy are the most productive and have the most impact on the economy, so when those large banks failed during the great recession in 2009, we had to prop them up economically, or they would have had a disproportionate negative impact on economy. It's a similar principle with large plants and animals across ecosystems."

Unfortunately, these large organisms are more susceptible to human pressures and climate change and take longer to recover from shocks, making them more prone to extinction.

"For hundreds of millions of years, Earth has been a planet of giants. In the last few thousand years, these large animals and plants have been whittled away, and this process continues today. Our paper shows why this loss of these giants matters for the very fabric of life on Earth, and why we must do everything possible to protect and restore them," said Yadvinder Malhi, leader of the ecosystems group at the Environmental Change Institute at the University of Oxford.

The findings help to answer an ongoing debate about where to channel limited conservation resources. While charismatic species such as the tiger or redwood tree have historically been most appealing and therefore effective at pulling in donations, some scientists worried that the focus on a certain subset of plants and animals could be coming at the cost of protecting other, less well-loved species.

"Our findings instead point to the importance of policies that emphasize the promotion of large trees and animals, as such policies will have a more disproportionate impact on biodiversity, ecosystem processes and climate mitigation," Enquist said. "We can use this model to focus our conservation concerns. For example, we can identify the forest that still contains some of the largest tress on the planet, or forests that have healthy size structure and prioritise them because they're more productive and resilient."

Author: Mikayla MacE | Source: University of Arizona [February 04, 2020]

* This article was originally published here

'Oldest bamboo' fossil from Eocene Patagonia turns out to be a conifer

A fossilised leafy branch from the early Eocene in Patagonia described in 1941 is still often cited as the oldest bamboo fossil and the main fossil evidence for a Gondwanan origin of bamboos. However, a recent examination by Dr. Peter Wilf from Pennsylvania State University revealed the real nature of Chusquea oxyphylla. The recent findings, published in the paper in the open-access journal Phytokeys, show that it is actually a conifer.

'Oldest bamboo' fossil from Eocene Patagonia turns out to be a conifer
The holotype of the species Retrophyllum oxyphyllum (comb. nov.),
previously thought to be the oldest known bamboo
[Credit: Peter Wilf]
The corrected identification is significant because the fossil in question was the only bamboo macrofossil still considered from the ancient southern supercontinent of Gondwana. The oldest microfossil evidence for bamboo in the Northern Hemisphere belongs to the Middle Eocene, while other South American fossils are not older than Pliocene.

Over the last decades, some authors have doubted whether the Patagonian fossil was really a bamboo or even a grass species at all. But despite its general significance, modern-day re-examinations of the original specimen were never published. Most scientists referring to it had a chance to study only a photograph found in the original publication from 1941 by the famous Argentine botanists Joaquin Frenguelli and Lorenzo Parodi.

In his recent study of the holotype specimen at Museo de La Plata, Argentina, Dr. Peter Wilf revealed that the fossil does not resemble members of the Chusquea genus or any other bamboo.

"There is no evidence of bamboo-type nodes, sheaths or ligules. Areas that may resemble any bamboo features consist only of the broken departure points of leaf bases diverging from the twig. The decurrent, extensively clasping leaves are quite unlike the characteristically pseudopetiolate leaves of bamboos, and the heterofacially twisted free-leaf bases do not occur in any bamboo or grass," wrote Dr. Wilf.

Instead, Wilf linked the holotype to the recently described fossils of the conifer genus Retrophyllum from the same fossil site, the prolific Laguna del Hunco fossil lake-beds in Chubut Province, Argentina. It matches precisely the distichous fossil foliage form of Retrophyllum spiralifolium, which was described based on a large set of data - a suite of 82 specimens collected from both Laguna del Hunco and the early middle Eocene Rio Pichileufu site in Rio Negro Province.

Retrophyllum is a genus of six living species of rainforest conifers. Its habitat lies in both the Neotropics and the tropical West Pacific.

The gathered evidence firmly confirms that Chusquea oxyphylla has nothing in common with bamboos. Thus, it requires renaming. Preserving the priority of the older name, Wilf combined Chusquea oxyphylla and Retrophyllum spiralifolium into Retrophyllum oxyphyllum.

The exclusion of a living New World bamboo genus from the overall floral list for Eocene Patagonia weakens the New World biogeographic signal of the late-Gondwanan vegetation of South America, which already showed much stronger links to living floras of the tropical West Pacific.

The strongest New World signal remaining in Eocene Patagonia based on well-described macrofossils comes from fossil fruits of Physalis (a genus of flowering plants including tomatillos and ground cherries), which is an entirely American genus, concludes Dr. Wilf.

Source: Pensoft Publishers [February 04, 2020]

* This article was originally published here

Mosaic X-rays reveal Peruvian mummy mysteries

Western researchers, including two undergraduate students, have become pivotal players in developing a mobile X-ray protocol that could transform how mummies are examined in the field.

Mosaic X-rays reveal Peruvian mummy mysteries
A CT scan of the skull of the same Peruvian mummy shows greater detail, including the textiles
that were placed around him in death [Credit: University of Western Ontario]
Anthropology professor Andrew Nelson and his team have pioneered a process to digitize and stitch together X-ray images so that they can non-destructively 'view' Peruvian mummy bundles in their entirety. The process will enable other anthropologists to conduct valuable work without damaging the objects.

"Lots of people have X-rayed mummies. But, as far as I know, we're the first to do the mosaic X-ray technique and do that digitally," Nelson explained.

Mummy bundles—called fardos—sometimes have been examined by unwrapping the textiles encasing the mummy. That process destroys the mummy and its context at least as much as it informs researchers about the past.

A less destructive but more time-consuming examination entails X-raying the bundles using film, which is then developed by hand, then transporting the heavy images home and analyzing them from afar.

But this new process is faster, portable and produces a far more complete picture. Here's how it works:

Researchers bring a suitcase-sized machine—Nelson's was funded by the Social Sciences and Humanities Research Council of Canada (SSHRC) – originally designed for use by veterinarians. The X-rays then go straight to the computer in digital form. No need to process into film or transport anything off-site. Those two-dimensional images are then electronically stitched together into composite, full-body images for immediate analyses.

Mosaic X-rays reveal Peruvian mummy mysteries
Researchers do a preliminary examination of a mummy bundle, one of hundreds discovered in Pachacamec, Peru, during
 a 2015 excavation to build a new museum. Pictured are, from left, Western student Lauren Poeta, Anthropology
 professor Andrew Nelson, Arizona researcher Suellen Gauld and archaeologist Sarita Fuentes Villalobos
of the Site Museum at Pachacamac [Credit: University of Western Ontario]
That scan can stand on its own as a more-than-basic record of the mummy's condition, position and setting. It can also offer rich enough detail for researchers to decide whether the mummy warrants further study through more detailed computer tomography (CT) scanning.

Last summer, Nelson's team conducted 880 X-rays and 31 CT scans in six days at the archaeological site of Pachacamac, Peru, where almost 200 fardos were discovered during excavation for a new museum in 2015.

This is the first time these mummy bundles—which date from about AD 1100 to AD1470—have been examined.

While the X-rays showed many mummies inside the bundles were no longer intact, the scans also indicated many were worthy of further non-destructive investigation.

"The great thing about doing the X-rays digitally and on site was the instant feedback we had," said David Seston, in his final year of undergraduate Anthropology studies and a key member of the team in data management and tech troubleshooting during the six-week study.

Anthropology Ph.D. student Joanna Motley pioneered the composite work in X-ray imaging.

Mosaic X-rays reveal Peruvian mummy mysteries
Undergraduate Anthropology student Lauren Poeta prepares a mummy bundle – called
  a fardo – of a Peruvian child for X-rays. The Western team has developed scanning
 processes that better assesses the mummy without damaging the fardo
[Credit: Andrew Nelson/Special to Western News]
Lauren Poeta, now in her fourth year of Anthropology, said the fieldwork in Peru—which included both teaching and learning from Peruvian researchers—offered an unparalleled opportunity in experiential learning.

"It was incredible because you don't expect to see that or have the opportunity to do that after just your third year. You get to do the experiential stuff. Instead of seeing pictures in two dimensions or in a textbook, this is totally different. You start to learn what to look for and what's important to see."

Poeta developed a standardized checklist of what researchers should be looking for as they try to discover how the fardos represent a microcosm of their society, including identifying the:

- Wrapping textile;

- Position of the mummy whether extended or with legs flexed towards their chest;

- Person's age, sex and any suspected health issues before death; and

- Type and location of any other artifacts buried with them.

Some fardos that have been CT-scanned and further analyzed show unusual objects wrapped with them.

Mosaic X-rays reveal Peruvian mummy mysteries
Credit: University of Western Ontario
Decorative shells. Stones. A mysterious folded disc they've nicknamed a 'taco." One person has a sharp object pierced through an eye socket. Another has a tattoo on one hand. One is surrounded by a 'cloud' of cotton seeds, be it to provide filler for the fardo or as a symbol for something else, no one yet knows.

Another question as-yet-unanswered is whether mummification—the preservation of tissue and clothing—was the main intent for wrapping and encasing the bodies, or whether mummification was an unintended result of the process, coupled with the dry climate and their burial in sand.

Together, all these details form clues into who these people were as individuals, how they lived, how they interacted with their community and how they were respected in death. They are, Nelson said, individually and collectively important to the study of pre-Columbian life in Peru.

Further study of the fardos and their images continues here year-round and by Peruvian researchers, with further work expected by a Western-Peruvian team this coming summer. "It's the awesome part of having a multi-year project," Nelson said.

A CT scan of the skull of the same Peruvian mummy shows greater detail, including the textiles that were placed around him in death. Credit: University of Western Ontario

Mosaic X-rays reveal Peruvian mummy mysteries
A CT scan of the skull of the same Peruvian mummy shows greater detail, including the textiles
 that were placed around him in death [Credit: University of Western Ontario]
Meanwhile, they have co-authored six collaborative papers about their work during and since last summer's research in Peru, and have presented research at archaeological and anthropological proceedings.

For Poeta, the experiential learning offered critical-thinking skills and a greater passion for anthropological fieldwork.

Seston said the experiential learning was both a personal and professional stretch.

"As an undergraduate, the chances of getting this kind of opportunity are incredibly rare. I knew when we went down there that this would change my perspective—but I never expected how much.

"A lot of work I do takes place on a computer. But being actually in the field and examining them changes my perspective 100 percent. It's not just an image on a screen. These are people and you have to respect them as people. You honour them by bringing them out and bringing back their stories."

Author: Debora Van Brenk | Source: University of Western Ontario [February 04, 2020]

* This article was originally published here

Wasp nests used to date ancient Australian rock art

Mud wasp nests have helped establish a date for one of the ancient styles of Aboriginal rock art in the Kimberley, Western Australia. University of Melbourne and ANSTO scientists put the Gwion Gwion art period around 12,000 years old.

Wasp nests used to date ancient Australian rock art
Wasp nests near the paintings have given scientists a major breakthrough
on Kimberley rock art [Credit: Damien Finch]
"This is the first time we have been able to confidently say Gwion style paintings were created around 12,000 years ago," said PhD student Damien Finch, from the School of Earth Sciences at the University of Melbourne. "No one has been able present the scientific evidence to say that before."

One wasp nest date suggested one Gwion painting was older than 16,000 years, but the pattern of the other 23 dates is consistent with the Gwion Gwion period being 12,000 years old.

The rock paintings, more than twice as old as the Giza Pyramids, depict graceful human figures with a wide range of decorations including headdresses, arm bands, and anklets. Some of the paintings are as small as 15cm, others are more than two metres high.

The details of the breakthrough are detailed in the paper 12,000-year-old Aboriginal rock art from the Kimberley region, Western Australia, now published in Science Advances.

Wasp nests used to date ancient Australian rock art
Two classic Gwion human figures with headdresses and arm
and waist decorations [Credit: Mark Jones]
More than 100 mud wasp nests collected from Kimberley sites, with the permission of the Traditional Owners, were crucial in identifying the age of the unique rock art.

"A painting beneath a wasp nest must be older than the nest, and a painting on top of a nest must be younger than the nest," Mr Finch said. "If you date enough of the nests, you build up a pattern and can narrow down an age range for paintings in a particular style."

Lack of organic matter in the pigment used to create the art had previously ruled out radiocarbon dating. But the University of Melbourne and ANSTO scientists were able to use dates on 24 mud wasp nests under and over the art to determine both maximum and minimum age constraints for paintings in the Gwion style.

The project was initiated by Professor Andy Gleadow and Professor Janet Hergt, from the School of Earth Sciences, and started in 2014 with funding from the Australian Research Council and the Kimberley Foundation. It is the first time in 20 years scientists have been able to date a range of these ancient artworks.