1,000-year-old mummy discovered in Peru

A team from the Université libre de Bruxelles's centre for archaeological research (CReA-Patrimoine) has completed a significant excavation in Pachacamac, Peru, where they have discovered an intact mummy in especially good condition. Pachacamac's status as a Pre-Colombian pilgrimage site under the Inca empire. is confirmed by further evidence.

The Pachacamac mummy inside the funeral bundle, surrounded by offerings
[Credit: ULB/P. Eeckhout]

Peter Eeckhout and his team's latest campaign of archaeological excavations has concluded with an exciting surprise: after nine weeks spent exploring the Pre-Colombian site of Pachacamac, in Peru, the researchers from CReA-Patrimoine (ULB Faculty of Philosophy and Social Sciences) have unearthed a mummy in especially good condition.

'The deceased is still wrapped in the enormous funeral bundle that served as a coffin,' points out professor Peter Eeckhout. 'Discoveries like this one are exceptionally scarce, and this mummy is incredibly well preserved. Samples were collected for carbon-14 dating, but the area in which it was discovered and the type of tomb suggest this individual was buried between 1000 and 1200 AD.'

The excavation was carried out as a part of the 'Ychsma' project, named after the region's native people, under the supervision of professor Eeckhout. Three monumental structures were explored during the campaign, including a sanctuary dedicated to the local ancestors.

Archaeologist Peter Eeckhout and a mummy's wooden false-head from a looted burial
[Credit: ULB/P. Eeckhout]

Under Inca rule, in the late 15th century, it appears to have been transformed into a water and healing temple. The archaeologists have discovered many offerings left by worshippers, such as Spondylus shells imported from Ecuador; these are associated with the influx of water during El Niño, and they symbolise fertility and abundance.

Before the Inca settled in the area, the sanctuary included large funerary chambers and numerous mummies, most of which were looted during the Spanish conquest. Miraculously, though, one of the chambers was found intact during the latest round of excavations: this is the funeral chamber that held the mummy.

Due to how well it was preserved, the researchers will be able to study it without needing to unwrap the bundle. Together with Christophe Moulherat (Musée du Quai Branly, Paris), they will soon examine the mummy using the latest techniques in medical imaging (X-ray scans, axial tomography, 3D reconstruction, etc.). This will enable them to determine the individual's position, any pathologies they might have suffered from, but also what offerings might be inside the bundle.

The other structures that were excavated are also related to worship: the first one, an Inca monument intended to host pilgrims and rituals, was built in several phases, each identified with a series of offerings such as seashells and precious objects.

The last structure explored was probably one of the 'chapels' for foreign pilgrims, referred to by Spanish monk Antonio de la Calancha in his 17th-century description of the site. There, the excavations also uncovered many 'foundation' offerings, including vases, dogs, and other animals, as well as a platform with a hole in the centre, where an idol was likely placed. The complex appears to have been designed around this idol, involved in religious activities with pilgrims.

According to researchers, all these discoveries indicate that Incas made considerable changes to the Pachacamac site, in order to create a large pilgrimage centre on Peru's Pacific coast. 'Deities and their worship played a major part in the life of Pre-Colombian societies,' concludes Peter Eeckhout.

'The Inca understood this very well, and integrated it into how they wielded their power. By promoting empire-wide worship, they contributed to creating a common sense of identity among the many different peoples that made up the empire. Pachacamac is one of the most striking examples of this.'

Source: Université libre de Bruxelles [May 24, 2018]

New details on discovery of 300-year-old San Jose shipwreck

The Woods Hole Oceanographic Institution (WHOI) recently obtained authorization by Maritime Archaeology Consultants (MAC), Switzerland AG, and the Colombian government to release new details from the successful search for the three-century old San José —a 62-gun, three-masted Spanish galleon ship that sank with a cargo believed to be worth billions of dollars. The ship, which is often called the “holy grail of shipwrecks,” went down with a treasure of gold, silver, and emeralds in 1708 during a battle with British ships in the War of Spanish Succession.

In November 2015, the MAC survey team and WHOI researchers returned to Colombian waters for a second search effort.
Side scan sonar images gave the crew the first indications of the find from of the wreck. To confirm the wreck’s identity,
REMUS descended to just 30 feet above the wreck where it was able to capture photos of a key distinguishing feature
of the San José—its cannons [Credit: REMUS image, Woods Hole Oceanographic Institution]

The legendary wreck was discovered off the coast of Cartagena, Colombia, on Nov. 27, 2015, by a team of international scientists and engineers during an expedition aboard the Colombian Navy research ship ARC Malpelo led by MAC’s Chief Project Archaeologist Roger Dooley. It was found more than 600 meters below the surface during a search initiated by MAC and approved by The Colombian Ministry of Culture. The search was supervised by Instituto Colombiano de Antropología e Historia (ICANH) and Dirección General Marítima (DIMAR).

“In order to ensure a successful search, we retained the services of Woods Hole Oceanographic Institution, which has an extensive and recognized expertise in deep water exploration,” said Dooley. “This partnership was key to the discovery of the San Jose.”

WHOI played a crucial role in both the search and discovery of the final resting place of the San José, which had remained a great mystery to marine archeologists, historians, governments, and treasure hunters for decades. Specifically, the institution provided and operated an autonomous underwater vehicle called REMUS 6000 to survey an area off Colombia’s Barú Peninsula.

A newly released gridded mosaic of images taken by the REMUS 6000 shows the complete wreck site
[Credit: Jeff Kaeli, Woods Hole Oceanographic Institution]

“The REMUS 6000 was the ideal tool for the job, since it’s capable of conducting long-duration missions over wide areas,” said WHOI engineer and expedition leader Mike Purcell.

Finding high-profile wrecks is nothing new for REMUS, which played an instrumental role in finding the wreckage of Air France 447 in 2011. The airplane had crashed in 2009 several hundred miles off the northeastern coast of Brazil and landed deep in the ocean on some of the most rugged seafloor terrain on Earth. REMUS was also used to map and photograph the Titanic wreck site during a 2010 expedition.

The San José discovery carries considerable cultural and historical significance for the Colombian government and people because of the ship’s treasure of cultural and historical artifacts and the clues they may provide about Europe’s economic, social, and political climate in the early 18th century. The Colombian Government plans to build a museum and world-class conservation laboratory to preserve and publicly display the wreck’s contents, including cannons, ceramics, and other artifacts.

The wreck was partially sediment-covered, but with the camera images from the lower altitude REMUS
missions, the crew was able to see new details, such as ceramics and other artifacts
[Credit: REMUS image, Woods Hole Oceanographic Institution]

REMUS was initially deployed off the Malpelo to survey an approved area in June 2015. The overall search area was divided into search blocks, and in the initial blocks surveyed, the shipwreck was not found. Unfortunately, the entire area of search blocks could not be completed in this first expedition due to time constraints. In November, the WHOI team along with MAC and under the supervision of ICANH and DIMAR, returned to the search area determined by previous historical research to finalize the survey in the blocks that had not been completed.

“During that November expedition, we got the first indications of the find from side scan sonar images of the wreck,” said Purcell. “From those images, we could see strong sonar signal returns, so we sent REMUS back down for a closer look to collect camera images.”

To confirm the wreck’s identity, REMUS descended to just 30 feet above the wreck where it was able to capture photos of a key distinguishing feature of the San José—its cannons.  Subsequent missions at lower altitudes showed engraved dolphins on the unique bronze cannons.

Tea cups at the wreck site [Credit: REMUS image, Woods Hole Oceanographic Institution]

“The wreck was partially sediment-covered, but with the camera images from the lower altitude missions, we were able to see new details in the wreckage and the resolution was good enough to make out the decorative carving on the cannons,” said Purcell. “MAC’s lead marine archaeologist, Roger Dooley, interpreted the images and confirmed that the San José had finally been found.”

“Once again, WHOI’s expertise in AUV technology and operations has resulted in an important discovery,” said WHOI Vice President for Marine Facilities and Operations Rob Munier. “We are pleased to have played a part in settling one of the great shipwreck mysteries for the benefit of the Colombian people and maritime history buffs worldwide. We look forward to our continued involvement to answer the basic oceanographic research questions associated with the find.”

Source: Woods Hole Oceanographic Institution [May 21, 2018]

Critically endangered South American forests were man made

Critically endangered South American forests thought to be the result of climate change were actually spread by ancient communities, archaeologists have found.

Campos da Serra y Floresta de Araucari [Credit: Copyright Jose Iriarte]

Huge swathes of land in Chile, Brazil and Argentina are covered with millions of Araucaria, or monkey puzzle trees, thanks to people planting or cultivating them more than a thousand years ago, a new study shows. Recent logging means the landscape is now one of the world's most at-risk environments.

It had been thought the forests expanded due to wetter and warmer weather. But the research shows the rapidly expanding pre-Columbian population of South America, Southern Jê communities, were really responsible.

New excavations and soil analysis shows the forests, still hugely culturally and economically important to people living in South America, expanded between 1,410 and 900 years ago because of population growth and cultural changes.

Dr Mark Robinson, from the University of Exeter, who led the British Academy and AHRC-FAPESP-funded research, said: "Our research shows these landscapes were man-made. Communities settled on grassland, and then - perhaps because they modified the soil, protected seedlings or even planted trees - established these forests in places where geographically they shouldn't have flourished."

Monkey puzzle forests [Credit: Copyright Mark Robinson]

The forests date back to the period when dinosaurs roamed. The iconic monkey puzzle tree, or Parana pine, has grown in the region for thousands of years. Its nuts were one of the most important food sources for ancient communities, attracted game for hunting when nuts were ripe. They were also a valuable source of timber, fuel and resin, and became an integral part of southern Jê cosmology. Communities still call themselves "people of the Araucaria", and hold festivals to celebrate the forests.

Of the 19 species of Araucaria tree, five are classified as endangered and two, including the Brazilian Araucaria angustifolia, are critically endangered. Reports from the late 1800s describe trees with diameters of over 2 m, reaching 42 m in height. Modern trees are only around 17.7 m tall.

The archaeological analysis began because the experts, from the University of Exeter, University of Reading, University of São Paulo, University of New Mexico, Universidade Federal de Pelotas and Universidade do Sul de Santa Catarina, noticed that in areas of low human activity forests are limited to south-facing slopes, whereas in areas of extensive archaeology, forests cover the entire landscape. They were able to analyse soil isotopes reflecting vegetation and archaeological evidence from Campo Belo do Sul, Santa Catarina State, Brazil, to test whether this pattern was directly related to past human activity.

The study shows the forests first expanded around 4,480 to 3,200 years ago, most likely near streams, and this may have been caused by a wetter climate. But a more rapid and extensive expansion across the whole region later happened between 1,410 and 900 years ago, when forests expanded into highland areas. The weather during this time was dry and less humid. This expansion of the forests coincides with population growth and increasingly complex and hierarchical societies in South America.

Monkey puzzle forests [Credit: Copyright Mark Robinson]

The expansion in forests reached a peak around 800 years ago. The number of people in South America declined 400 years ago when European settlers arrived in the area. The population did not begin to recover until the 19 century, when loggers began exploiting the Araucaria forests for timber.

Professor José Iriarte, from the University of Exeter, another member of the research team, said: "This study shows the Araucaria forests were expanded beyond their natural boundaries, they were used sustainably for hundreds of years, and conservation strategies must reflect this so they balance protection, heritage and economic development."

The study is published in the journal Scientific Reports.

Source: University of Exter [May 17, 2018]

Europium points to new suspect in continental mystery

Clues from some unusual Arizona rocks pointed Rice University scientists toward a discovery -- a subtle chemical signature in rocks the world over -- that could answer a long-standing mystery: What stole the iron from Earth's continents?

The Cordillera Huayhuash in the Peruvian Andes as seen from the International Space Station in May 2008
[Credit: ISS Expedition 17/NASA]

The find has weighty implications. If the iron content of continental rocks was a bit greater, as it is in the rocks beneath Earth's oceans, for example, our atmosphere might look more like that of Mars, a planet so littered with rusty, oxidized rocks that it appears red even from Earth.

In a new paper published in Science Advances, Rice petrologists Cin-Ty Lee, Ming Tang, Monica Erdman and Graham Eldridge make a case that garnet steals the most iron from continents. The hypothesis flies in the face of 40-plus years of geophysical thinking, and Tang, a postdoctoral fellow, and Lee, professor and chair of the Department of Earth, Environmental and Planetary Sciences at Rice, said they expect a healthy dose of skepticism from peers.

"The standard view, which even we agreed with and wrote papers agreeing with, is that iron is removed from continental crust by another mineral called magnetite," Lee said. "I think people haven't thought much about garnet, possibly because it doesn't show up very much and magnetite shows up in a lot of samples."

Building a case for or against either mineral isn't easy because the iron they're accused of stealing disappears many miles below active volcanoes. The prime example today is the arc of volcanoes that span the Andes Mountains in South America. Similar continental arcs are believed to have formed much of Earth's major landmasses, but scientists have no instruments capable of directly observing what happens beneath continental volcanic arcs. Instead, the missing iron mystery must be solved with deductive reasoning about Earth's inner workings and rare rocks that hold clues from the scene of the crime.

"The accepted wisdom is that magnetite pulls iron from the melt before the melt rises and gets erupted out at continental arcs," Tang said. "Iron depletion is most pronounced at continental arcs, where the crust is thick, and much less so in island arcs, where the crust is thin. However, there is no obvious explanation for why the extent of magnetite involvement would correlate with thickness of the crust."

But garnet does correlate. Almandine, an iron-laden type of garnet, is more easily made under high pressure and high temperature -- the kind of conditions that exist in the subduction zone beneath the Andes, where continental crust can be as much as 50 miles thick, Lee said.

A garnet pyroxenite xenolith from Sierra Nevada, Calif. [Credit; C. Lee/Rice University]

Tang might never have suspected garnet were it not for a field trip by Lee and students to central Arizona in 2009 to look for xenoliths.

"'Xeno' meaning foreign and 'lith' meaning rock," Lee said. "They are much older than the volcanoes they came from. These volcanoes ripped up the rocks from 60 to 80 kilometers deep, and the xenoliths came up as little fragments. It's difficult to find rocks like this, but when you do, they give you a window, a direct window, into the deep parts of the continental arc, the root."

Erdman, then a doctoral student in Lee's lab, conducted an initial analysis of the xenoliths, and established that they were formed in a continental arc setting and were rich in garnet. Two years later, Rice undergraduate Graham Eldridge spent a summer characterizing rare earth elements in the xenoliths and found hints that they contained unusual Europium ratios.

Europium typically forms minerals that allow each of its atoms to share three electrons with nearby atoms, an "oxidation state" that chemists notate as Eu+3. Europium also forms minerals in which it shares two electrons, and the notation for this less-oxidized state is Eu+2. In an oxygen-plentiful environment, Europium occurs in its highest oxidation state (Eu+3), but at more intermediate levels of oxygen in the mantle it can occur in both Eu+2 and Eu+3 states.

The oxidation states of the Europium that Eldridge found in the Arizona xenoliths suggested they formed in less-oxidized conditions than would be expected in the magnetite scenario, but there was not enough data to confirm this hunch.

"Continental arcs happen at subduction zones, where an oceanic tectonic plate slides below a continental plate," Lee said. "When the oceanic plate is recycled back into the mantle, it is widely thought to introduce a lot of oxygen into the mantle. The magnetite scenario for iron depletion relies heavily on the idea that these subduction zones are highly oxidized at depth."

Tang joined Lee's group in 2016 and was intrigued by the Europium ratios in the xenoliths. Tang had extensive experience characterizing Europium as part of his doctoral studies at the University of Maryland, and he began conducting hundreds of painstaking measurements to more precisely characterize the Europium ratios in the Arizona xenoliths.

The quality of Tang's data not only confirmed the low-oxidation Europium ratios but allowed him to develop a new hypothesis that tied everything together: the garnet, the Europium ratios and the fact that thicker continental crusts are more iron-depleted than thinner island arc crusts.

"As the crustal column gets thicker and thicker, as it is at continental arcs, the temperature and pressure are great enough to produce these iron-rich garnets, which are heavy and sink out," Tang said. "The iron they pull out is ferrous iron (Fe+2) and not highly oxidized. It goes back into the mantle, and the iron that remains in the melt and erupts to become part of the continental crust becomes even more oxidized on its way to the surface."

To test the hypothesis on a global scale, Tang spent several months examining records in the Max Planck Institute's GEOROC database, a comprehensive global collection of published analyses of volcanic rocks and mantle xenoliths collected all over the world.

"There is a relationship between iron depletion and the garnet fractionation signatures, which means magmas that fractionate more garnet are more depleted in iron," Tang said. "This is born out in the global record, but the evidence is something that wouldn't be obvious from looking at just one or two cases. It's the kind of thing that requires a global database, and those have only recently become available."

Lee said the find has important implications for Earth's ability to sustain an oxygen-rich atmosphere.

"Photosynthesis produces oxygen, but the primary thing that takes oxygen out of circulation for a long time is oxidation with the crust," Lee said. "If what comes out of volcanoes to form the continents is effectively already rusted, then it won't immediately react with and deplete the oxygen in the atmosphere."

After submitting their results for peer-reviewed publication, Tang and Lee found that renowned Australian petrologist Ted Ringwood and colleagues had implicated garnet rather than magnetite in a few papers published 50 years ago.

"Many of the people in our field have a scientific lineage that goes back to Ringwood," Lee said. "I'm sure many of them may take one look and think this is a crazy idea, but considering that their great-great-grandfather, academically speaking, had speculated on this, perhaps we're in good company."

Source: Rice University [May 16, 2018]

Understanding Andean concepts of death and renewal

Research in the Andes has yielded evidence for a complex association between settlement sites and mortuary monuments, tied to concepts of death, ancestor veneration and water.

The huaca-huanca (RF5) of Kipia. A: detail of RF5 showing imitation of landscape features; B: carved offering pit
containing andesite fragments, river-rolled pebbles and ceramic; C: offering pit containing andesite fragments
[Credit: Kevin Lane et al. Open Archaeology (2018]

In the case-study 'Carved Rocks and Subterranean Burials at Kipia, Ancash, AD 1000 - 1532' published in De Gruyter's journal Open Archaeology, authors Kevin Lane, Emma Pomeroy and Milton Reynaldo Lújan Davila analyse the Prehispanic-Spanish Colonial multi-faceted site of Kipia, in the Ancash highlands in Peru.

The site contains two small settlements, a cosmological centre, and a funerary sector of subterranean tombs. The author's study reveals the stunning relation between ceremonial sites and cemeteries which underpins complex Andean concepts of death and renewal.

The authors paid special attention to the cosmological core of the site, which is arranged around a series of carved rocks -- huanca -, a central huaca ¬(deity/ancestor), and a communal subterranean tomb. It was discovered that the various features of the site can be related to the surrounding landscape, which is remarkable since archaeological examples establishing a direct link between site and landscape in the Andes are not common. Even more remarkable is the fact that the discovery is supplemented by bioarchaeological data (the analyzed subterranean tomb -- pukullo -- presented in the research).

In the Prehispanic Andes the landscape was innately animated, and Kipia is positioned at the center of its particular physical environment. In this sense, Kipia was not just a repository for the dead, but more widely a place of communion between the living and the departed, associated to the central huaca-huanca, and the other carved rock-faces.

The importance of Kipia lies in its role as a local huaca dedicated to the lightening deity in which overt manifestations of life and death cohabited. In turn, Kipia linked into a network of other larger potentially sacred sites, such as the lakes.

Excavated, comparative highland Late Intermediate Period (AD 1000-1450) tombs are limited, especially ones linked to important sacred sites. In synthesis, this study makes a valuable contribution to the very limited literature on the use of communal burial structures in the Andes that is based on excavation, detailed osteological analysis and is in direct connection with a particular sacred landscape.

Dr. Alexis Mantha, an expert on Andean Archaeology from Université Montréal, outlines: "This article provides a very interesting and rare case study of a complex animated ritual landscape in the highlands of Ancash, Peru, during late Andean prehistory. The authors convincingly examine the intricate ritual relationships among the skeletal content of a subterranean tomb (pukullo) and other features of the surrounding landscape such as a stone monolith (huanca), peaks and highland lakes."

Source: De Gruyter [May 15, 2018]

Researchers uncover genomic info linking extinct giant ground sloth to modern species

Researchers have uncovered important genomic data from the remains of an ancient giant ground sloth, or Mylodon darwinii, the emblematic creature named after Charles Darwin, whose discovery of fossilized remains in South America is considered to be one of his significant scientific achievements.

The Mylodon cave in which the bone analyzed by researchers was collected
[Credit: Walter Ferry Dissmann]

Using a bone fragment which dates back nearly 13,000 years, scientists teased out and reconstructed DNA fragments to obtain a high-quality mitochondrial genome and nuclear genomic information. The analysis, they say, proves for the first time that the giant ground sloth--which went extinct approximately 10,000 years ago--is a close relative of the modern two-fingered sloth, believed to be one of the world's slowest mammals.

The research, published online in the Proceedings of the Royal Society B, suggests the two species diverged from one another approximately 22 million years ago. The much smaller, modern sloth evolved over time to inhabit trees, where it spends virtually its entire life suspended upside down.

"Our study confirms the convergent evolution of the two, tree dwelling modern sloths from two distinct lineages of extinct giant ground sloths," says Hendrik Poinar, a lead author of the study and director of the McMaster Ancient DNA Centre and principal investigator at the Michael G. DeGroote Institute for Infectious Disease Research. "This means tree-living evolved independently, twice, which is remarkable."

Scientists say the sample was exceptionally well-preserved. It was taken from the famous Mylodon Cave in Chile, which derives its name from the numerous remains of ground sloths found inside. The constant cold and dry conditions of the cave have preserved a scientific treasure trove including bones, claws, feces and even large pieces of mummified skin still covered with blond fur.

"The incredible conservation of the bone sample we used in this study offers promising prospects for sequencing the full genome of this extinct species because of the high percentage of DNA that it contains," says Frédéric Delsuc, co-author of the paper and Director of Research at the Centre National de Recherche, France.

"This will certainly generate more insights and information into their unique features and ultimate extinction," he says.

These remains found within the exceptional site of Mylodon Cave, in Patagonia, Chile, were the first non-human samples used by scientists in early genetic tests which yielded genuine ancient DNA.

Advances in sequencing technology have led to a deeper understanding of ancient and extinct species, including the Columbian and woolly mammoths, giant lemurs and steppe bison.

Source: McMaster University [May 15, 2018]

Darwin's finches - where did they actually come from?

In 1835, Charles Darwin visited the Galapagos Islands and discovered a group of birds that would shape his groundbreaking theory of natural selection. Darwin's Finches are now well-known as a textbook example of animal evolution. But just where did a species synonymous with the discovery of evolution come from? A new study from The Auk: Ornithological Advances presents some of the best models to date on where these birds actually originated.

Española cactus finch (Geospiza conirostris) [Credit: S. Taylor]

San Diego State University's Erik Funk and Kevin Burns set out to determine the ancestral biogeography - how a species' distribution varies over space and time - of Coerebinae. Coerebinae is a subfamily of birds called tanagers. This group includes the famous Darwin's Finches and their fourteen closest relatives. Using state-of-the-art statistical software, Funk and Burns modeled two competing hypotheses.

Both hypothesis models contained the same geographic area of the Galapagos, South America, and the Caribbean, but one model divided this area into more subregions than the other. The subregions were based on areas that shared similar plants and animals, such as the the Amazon or the Andes. When eight subregions were included in the model, the results indicated that the Caribbean, not the closer South American mainland, was more likely to be the origin of this bird group. However, the opposing model contains only five regions and indicates that the South American mainland is as likely as the Caribbean to be the home to Darwin's Finches' ancestors. The authors conclude that the current data suggest both potential origin sites are equally likely.

Funk says, "the results...were a bit surprising, because they suggested a dispersal pattern that was not necessarily the most 'straightforward' explanation for how these birds arrived in the Galápagos. I think one of the big take-away messages here is the possibility that biogeographic events, like dispersal, may not necessarily happen like logic tells us they should. Darwin's finches are such a highly studied group, and it is often taken for granted they arrived from mainland South America, but hopefully our results show readers that there is no more support for this hypothesis than there is for a Caribbean origin."

Funk and Burns suggested the successful colonization of the Galapagos Islands was a result of two traits. First, the finches' ancestors were more likely to wander than other species and consequently encountered islands more often. Second, these ancestors had a large amount of genetic variation in bill size and shape. This diversity in bill morphology allowed them to establish themselves and exploit their newfound niche. Better understanding the biogeography of Darwin's Finches allows scientists to learn how animals move, and how this affects their subsequent evolution and ability to adapt to new or changing environments.

"In 2018, we still have fundamental things to learn about one of the most studied and celebrated groups of birds, Darwin's Finches. Perhaps we should be calling them Darwin's Tanagers because it is Burns' tree of life for these birds, nesting them firmly in Tanagers, that is enabling new insights into the evolution, morphology, and origins of this remarkable group of birds. Funk and Burns use new biogeographic techniques in conjunction with recent phylogenies to explore the origins of Darwin's Finches," adds Shannon Hackett, Associate Curator in the Department of Zoology, and Head of the Field Museum's Bird Division at the Field Museum, who is an avian diversity and phylogeny expert who was not involved in the research.

Source: American Ornithological Society [May 09, 2018]

Scientists hark back to Pleistocene to trace prioritary areas for conservation

Identifying priority areas for action is a major challenge in biodiversity conservation projects. A group of researchers have chosen an approach based on past scenarios to try to understand the history of climate conditions in the regions analyzed.

Atlantic Forest Fragmentation [Credit: Cnes - Spot Satellite Image via Wikimedia]

"The regions that have suffered least from climate change in the last 21,000 years are those in which the fewest local extinctions have occurred. These regions stand out for their higher species richness ratios, genetic diversity among species and gene variability within the same population," said Thadeu Sobral-Souza, a biologist at the Rio Claro campus of São Paulo State University (UNESP) in Brazil.

The greater a population's genetic diversity, the higher its chances of surviving environmental change. Sobral-Souza is one of the authors of a paper that describes a methodology to identify climatically stable Amazon and Atlantic Rainforest areas that can be prioritized in conservation strategies. The study also determined which protected areas are already located in climatically stable areas.

Some of the group's findings have been published in the journal Acta Oecologica. The research was supported by the São Paulo Research Foundation - FAPESP via a project in which Milton Cezar Ribeiro, a professor in UNESP Ecology Department, was principal investigator.

To determine which areas are climatically stable, the researchers first had to estimate the distributions of both biomes in the past, especially before most of the Atlantic Rainforest was destroyed. They used ecological niche modeling to simulate the distribution of these forests both now and in previous eras.

New technologies have facilitated the development of techniques to generate useful information from incomplete data. Species ecological niche modeling is one example. All species of animals and plants obey ecological rules that determine their geographical distribution. Even partial knowledge of the geographical distribution of a species in the present and the levels of environmental variation it tolerates (temperature highs and lows, rainfall, and so on) can be fed into computer algorithms and geoprocessing tools to obtain a quantitative representation of its ecological distribution.

Incomplete data for the geographical location of a species can be used to discover its current (or potential) distribution in the environment. Similarly, estimates of past climate conditions can be used to simulate the spatial distribution of species in previous periods.

"Although ecological niche modeling is normally used to infer species distribution, the technique is also deployed to predict biome delimitation by modeling the biome," Sobral-Souza said.

To predict variations in biome distribution over time, the researchers selected occurrence points using a geographical filter based on the current delimitations of the Amazon and Atlantic Rainforest biomes. Several atmosphere-ocean global circulation models that infer past global climate currently exist. "We used five of these models as data sources for simulations of the Amazon and Atlantic Rainforest climate in the past," Sobral-Souza said.

The researchers estimated the distributions of the two biomes using data such as annual mean temperature and annual precipitation as variables. The models were constructed on the basis of the current climate scenario and simulated past scenarios for the peak of the last ice age in the Late Pleistocene, 21,000 years ago, and the middle of the Holocene, 6,000 years ago.

Map of the Atlantic Forest ecoregions as delineated by the WWF. The yellow line approximately
 encloses the forest's distribution [Credit: NASA via Wikimedia]

The simulations showed that the potential area of the Amazon biome 21,000 years ago was 3.28 million km², compared with a current potential area of 4.46M km², while the corresponding numbers for the Atlantic Rainforest were 3.85M km² and only 770,000 km², an 80% decrease.

To calculate climatically stable areas in the two biomes, the researchers superimposed the two paleomaps showing the biomes' distributions 21,000 and 6,000 years ago onto the map of their current distribution, thereby selecting the areas predicted to be suitable for biome occurrence in the three scenarios.

"Once we'd identified the overlaps showing climatically stable areas in all the scenarios, we analyzed the efficiency of currently protected areas," Ribeiro said.

They did this by mapping all protected areas and superimposing this map on the previous ones to show which protected areas were inside climatically stable areas and which were not.

To propose priority conservation areas, they mapped unprotected climatically stable areas and used the Intact Forest Landscapes database to infer which of these unprotected areas contain intact remnants of primary forest without anthropogenic modification, considering only large connected patches and excluding small or unconnected remnants.

Climate stability

Next, the researchers assigned each of these patches to one of three conservation priority categories. Very high priority areas were climatically stable, unprotected, and with large intact forest remnants.

High priority areas, the second category, were climatically stable, unprotected, and with fragmented forest remnants. The third category comprised medium priority areas, with more recent climate stability (in the last 6,000 years) and unprotected intact forest remnants.

"The results revealed three unconnected blocks of climatically stable areas in the Atlantic Rainforest biome, all near the coast," Ribeiro said. "The northernmost block comprises Paraíba and Pernambuco States all the way along the Zona da Mata region. The second coincides with the Serra do Mar and Serra da Mantiqueira ranges in São Paulo State, Serra dos Órgãos in Rio de Janeiro State, and Zona da Mata in Minas Gerais.

"In the Amazon, the climatically stable areas are broad and continuous, covering most of the currently existing biome. Most of them occur in eastern Amazonia, although smaller remnants were identified along the western and southern boundaries of the forest."

The researchers created an efficiency index, defined as the percentage of protected areas that encompass climatically stable areas. They inferred higher efficiency for protected areas in the Amazon than for those in the Atlantic Rainforest, finding that 40.1% of climatically stable areas in the Amazon are protected, compared with only 7.1% of climatically stable areas in the Atlantic Rainforest.

"The Amazon is more stable climatically than the Atlantic Rainforest, and protected areas in the latter are less efficient than protected areas in the former," Ribeiro said.

Amazon raiforest, Brazil [Credit: Lunae Parracho/AFP/Getty Images]

In the Amazon, the study identified climatically stable areas in all three conservation priority categories - very high priority, high priority and medium priority. The areas of very high conservation priority in the Amazon biome are primary forest areas of western Amazonas State in the region bordering Peru, Colombia and Venezuela.

"Its geographical proximity to protected areas suggests that the creation of new protected areas or the enlargement of existing areas to include these high-priority areas could be an effective conservation strategy," Sobral-Souza said.

The high-priority areas in the Amazon are fragmented forests in climatically stable areas and are therefore in need of restoration. The high priority areas in western Amazonia are located near existing protected areas or intact fragments. In eastern Amazonia, they are forest patches surrounded by croplands and pasture, distant from intact forest areas.

"In these cases, reforestation is necessary to increase the efficiency of the protected areas in the region. The Amazon still has a major opportunity to expand conservation areas," Ribeiro said.

Sobral-Souza stressed that the situation is catastrophic in the Atlantic Rainforest biome. "No high-priority areas for conservation were identified because no more forest areas exist there. No intact forest or even fragments are left. Everything has been cleared in the last 500 years," he said.

The main climatically stable Atlantic Rainforest areas are small. They are relicts classified as high priority conservation areas. Only a few remnants exceed 10,000 hectares, and many occur in areas with low climate stability. The most important are in Pernambuco's Zona da Mata or the Serra do Mar State Park, "the largest Atlantic Rainforest remnant in Brazil," Sobral-Souza noted.

Source: São Paulo Research Foundation – FAPESP [May 04, 2018]