Argentine fossils take oak and beech family history far into Southern Hemisphere

By: Thomas Schmitt Attorney on June 06, 2019 / comment : 0 Argentina, Fossils, Palaeoclimate, Palaeontology, Patagonia

One of the world's most important plant families has a history extending much farther south than any live or fossil specimen previously recorded, as shown by chinquapin fruit and leaf fossils unearthed in Patagonia, Argentina, according to researchers.

Discovery photo of the mature Castanopsis fruiting spike fossil with four nuts enclosed in scaly cupules, showing the part and counterpart on the split surface at Laguna del Hunco [Credit: Peter Wilf, Penn State University]

"The oak and beech family is recognized everywhere as one of the most important plant groups and has always been considered northern," said Peter Wilf, professor of geosciences and associate in the Earth and Environmental Systems Institute, Penn State. "We're adding a huge spatial dimension to the history of the Fagaceae family, and that's exciting." The plant family also includes chestnuts and the closely related chinquapins.

Common in the Northern Hemisphere and Asian tropics, Fagaceae cross the equator only in Southeast Asia, and even there just barely. The latest study, published in Science, extends the family's biogeographical history and suggests a Gondwanan supercontinent legacy in Asian rainforests larger than previously thought.

The researchers first found fossils resembling some oak leaves, with straight secondary veins and one tooth per secondary vein, at Laguna del Hunco, Chubut province. The leaves comprise about 10 percent of the thousands of 52-million-year-old leaf fossils, representing almost 200 species, found at the site over two decades in a long-term project between Penn State, Cornell University and Museo Paleontológico Egidio Feruglio (MEF), Trelew, Argentina.

Detail of the mature Castanopsis fruiting spike fossil with four nuts, dark and turned to coal, enclosed in scaly cupules. Cupule at top is splitting open [Credit: Peter Wilf, Penn State University]

For years the researchers hesitated to classify the leaves, because paleobotanist Edward Berry had assigned similar fossils to another family, and any claim of Fagaceae at so remote a location would require much more supporting evidence.

Later, the team unearthed rare fruit fossils -- two fruit clusters, one with more than 110 immature fruits -- at the site and compared them to living relatives. They found that these were fossils of ancient Castanopsis, an Asian chinquapin that today dominates the biodiverse, lower elevation mountain rainforests of Southeast Asia.

"One of the first clues was a little lip where the fruit is splitting open," Wilf said. "I recognized this lip as being similar to the fruit of the Japanese chinquapin. Then I realized there's a nut inside."

Detail of a single immature fruit of living Castanopsis acuminatissima, New Guinea, showing scaly surface and preservation of three slender styles (pollen-receiving organs) at top [Credit: Peter Wilf, Penn State University]

The nuts are fully encased in a scaly outer covering, or cupule, that splits open when the fruits mature. The cupules are arranged on a spike-like fruiting axis, and the young nuts retain delicate parts from their flowering stage. Their features are just like the living Castanopsis, Wilf said, and the fruits confirm that the leaves are Fagaceae.

"This is the first confirmed evidence that Fagaceae, considered restricted to the Northern Hemisphere, was in the Southern Hemisphere," said Maria Gandolfo, associate professor, Cornell University. "This is remarkable and allows us to rethink the origins of the fossil flora."

The fossils date to the early Eocene 52.2 million years ago. They are the only fossilized or living Fagaceae ever found south of the Malay Archipelago, the island chain just north of Australia.

Large fossil Fagaceae leaf from Laguna del Hunco with well-preserved details [Credit: Peter Wilf, Penn State University]

During the globally warm early Eocene there was no polar ice, and South America, Antarctica and Australia had not completely separated, comprising the final stage of the Gondwanan supercontinent. The researchers think animals had helped disperse the chinquapin's ancestors from North to South America at an earlier time. The plants thrived in the wet Patagonian rainforest, whose closest modern analog is the mountain rainforests of New Guinea.

"Before the current semi-desert conditions, trees covered Patagonia," said Rubén Cúneo, director of MEF. "Changes in climatic conditions turned it into a shrubland, and the trees were displaced."

The chinquapins may have also ranged into then-adjacent Antarctica and on to Australia, said Wilf. Castanopsis may have survived in Australia until the continent collided with Southeast Asia, where today chinquapins are keystone species, providing forest structure and food and habitat for birds, insects and mammals.

The Laguna del Hunco fossil site in Chubut, Patagonian Argentina. Paleontologists at centre of frame are collecting diverse plant fossils, including abundant leaves of Fagaceae [Credit: Peter Wilf, Penn State University]

"We're finding, in the same rocks as Castanopsis, fossils of many other plants that live with it today in New Guinea and elsewhere, including ferns, conifers and flowering plants," said Wilf. "You can trace some of the associations with Castanopsis seen in Eocene Argentina to southern China and beyond."

Today, Castanopsis plays an important role in intercepting year-round mountain precipitation that delivers clean water for drinking, fishing and agriculture to more than half a billion people and sustains diverse freshwater and coastal ecosystems. However, humans are clearing these rainforests for timber, development and crop cultivation, and modern climate change is increasing droughts and fire frequency.

"These plants are adaptable if given time and space," Wilf said, adding Castanopsis' trek from Patagonia to Southeast Asia occurred over millions of years and thousands of miles. "But the pace of change today is hundreds of times faster than in geologic time. The animals that depend on these plants are adaptable only to the extent that the plants are, and we are one of the animals that depend on this system. If we lose mountain rainforests, really fast we lose reliable water flows for agriculture, clean coral reefs offshore, biodiversity and much more."

This study has implications for extinction in the face of climate change, according to Kevin Nixon, professor and L.H. Bailey Hortorium curator, Cornell University. He said Castanopsis went extinct in Patagonia due to a major extinction caused by the slow cooling and drying of the climate that occurred with the glaciation of Antarctica and the rise of the Andes.

"Those kinds of climate changes can have massive effects on biodiversity," Nixon said. "The relevance of understanding this is we can start to look at extinction processes. The better we can understand what causes extinction, the better we can deal with it."

Author: Francisco Tutella | Source: Pennsylvania State University [June 06, 2019]

Patagonia ice sheets thicker than previously thought, study finds

By: Thomas Schmitt Attorney on June 03, 2019 / comment : 0 Climate Change, Earth Science, Ecosystems, Natural Heritage, Patagonia, South America

After conducting a comprehensive, seven-year survey of Patagonia, glaciologists from the University of California, Irvine and partner institutions in Argentina and Chile have concluded that the ice sheets in this vast region of South America are considerably more massive than expected.

Glaciers in South America’s Patagonia region, including Argentina’s Viedma Glacier (pictured), are much thicker than expected, according to a seven-year survey conducted by scientists from UCI, Chile and Argentina that will enable researchers and planners to more accurately model the effects of global warming and plan for potential disruptions in freshwater resources [Credit: Jeremie Mouginot/UCI]

Through a combination of ground observations and airborne gravity and radar sounding methods, the scientists created the most complete ice density map of the area to date and found that some glaciers are as much as a mile (1,600 meters) thick. Their findings were published today in the American Geophysical Union journal Geophysical Research Letters.

"We did not think the ice fields on the Patagonian plateau could be quite that substantial," said co-author Eric Rignot, Donald Bren Professor and chair of Earth system science at UCI. "As a result of this multinational research project, we found that - added together - the northern and southern portions of Patagonia clearly hold more ice than anticipated, roughly 40 times the ice volume of the European Alps."

Patagonia is home to the largest ice fields in the Southern Hemisphere outside Antarctica, and its glaciers are among the fastest-moving in the world. Surface elevation observations from satellite radar altimetry and optical imagery have shown that most of the ice slabs in the region have been thinning rapidly over the past four decades. The contribution to global sea level rise from their melting has increased at an accelerating pace during that time.

Study co-author M. Gabriela Lenzano, a researcher with Argentina's National Scientific and Technical Research Council, said the results will "help the scientific community better explain the interactions and consequences of ice sheet dynamics and climate on this cold environment - and the impact on communities and ecosystems downstream."

With more precise knowledge of the size and shape of the glaciers in this highly protected region - much of which is contained in one of the world's largest national park systems - researchers and planners will be able to more accurately model the effects of global warming and plan for potential disruptions in freshwater resources that serve its inhabitants.

"This is why having accurate maps of the ice thickness is a priority," said lead author Romain Millan, who was a UCI graduate student in Earth system science for the bulk of this research project and is now a postdoctoral scholar at the Institute of Environmental Geosciences in Grenoble, France. "It is fundamental to get the right contours and depth of the glacial valleys; otherwise, simulations of glacier retreat will always be wrong."

The difficulty in quantifying bed elevation and thickness has limited scientists' ability to predict the region's potential contribution to sea level rise; model glacier dynamics in response to climate change; study the impacts on freshwater resources; or prepare against such hazards as lake outburst flooding, which occurs when a dam containing a glacial lake fails.

Past attempts to gauge the total heft of the ice have fallen short, because traditional sounding techniques were limited to the shallowest sections of the ice field. Another obstacle has been the temperate nature of Patagonian ice. The frozen water in the glaciers is near its melting point from the top to the bottom; the higher water content makes this kind of ice more difficult to measure with radar.

To overcome these challenges, the scientists took to the skies, flying over broad stretches of terrain in helicopters and fixed-wing aircraft equipped with gravimeters, devices that can determine the ice volume by reading changes in Earth's gravitational field. The addition of data collected by glaciologists from Chile's Center for Scientific Studies, who had mapped ice thickness with low-frequency airborne radar sounding since 2002, was instrumental in creating a more comprehensive description of the area's conditions.

"This research has been enhanced and successfully completed thanks to our collaboration with the Rignot group at UCI and our Argentinean colleagues, with whom we have worked at both sides of the southern Patagonia ice field - disregarding the political border that divides the region," said co-author Andrés Rivera of the Chilean center.

Source: University of California - Irvine [June 03, 2019]

Abrupt climate change drove early South American population decline

By: Thomas Schmitt Attorney on May 09, 2019 / comment : 0 Americas, Archaeology, Earth Science, Indigenous Cultures, Palaeoclimate, Patagonia, South America

Abrupt climate change some 8,000 years ago led to a dramatic decline in early South American populations, suggests new UCL research.

Patagonia landscape [Credit: Celine Harrand/Flickr]

The study, published in Scientific Reports, is the first to demonstrate how widespread the decline was and the scale at which population decline took place 8,000 to 6,000 years ago.

"Archaeologists working in South America have broadly known that some 8,200 years ago, inhabited sites in various places across the continent were suddenly abandoned. In our study we wanted to connect the dots between disparate records that span the Northern Andes, through the Amazon, to the southern tip of Patagonia and all areas in between," said lead author, Dr Philip Riris (UCL Institute of Archaeology).

"Unpredictable levels of rainfall, particularly in the tropics, appear to have had a negative impact on pre-Columbian populations until 6,000 years ago, after which recovery is evident. This recovery appears to correlate with cultural practices surrounding tropical plant management and early crop cultivation, possibly acting as buffers when wild resources were less predictable," added Dr Riris.

The study focused on the transition to the Middle Holocene (itself spanning 8,200 and 4,200 years ago), a period of particularly profound change when hunter-gatherer populations were already experimenting with different domestic plants, and forming new cultural habits to suit both landscape and climate change.

While the research shows that there was a significant disruption to population, the study highlights that indigenous people of South America were thriving before and after the middle Holocene.

Co-author, Dr Manuel Arroyo-Kalin (UCL Institute of Archaeology), said: "In the years leading up to population decline, we can see that population sizes were unharmed. This would suggest that early Holocene populations, probably with a social memory of abrupt climate change during the Pleistocene-Holocene transition, developed successful strategies to deal with climate change.

"Abandonment of certain regions and the need to adapt quickly to new circumstances may have promoted the exploration of alternative strategies and new forms of subsistence, including the early adoption of low scale cultivation of domestic plants. Viewed in the context of at least 14,000 years of human presence in South America, the events of the Middle Holocene are a key part of indigenous South Americans' cultural resilience to abrupt and unexpected change."

In this new study, archaeologists examined data from nearly 1,400 sites consisting of more than 5,000 radiocarbon dates to understand how population changed over time, and cross-referenced this information with climate data.

Dr Riris explained: "We studied ancient records of rainfall such as marine sediments for evidence of exceptional climate events. Within windows of 100 years, we compared the Middle Holocene to the prevalent patterns before and after 8,200 years ago. Normal patterns of rainfall suggest on average an unusually dry or wet year every 16-20 years, while under highly variable conditions this increases to every 5 years or so. This puts in perspective the challenge that indigenous communities would have faced."

The authors believe that the research offers crucial historical context on how ancient indigenous South American populations dealt with climate change.

Dr Arroyo-Kalin concluded: "Our study brings a demographic dimension to bear on understandings of the effects of past climate change, and the challenges that were faced by indigenous South Americans in different places. This understanding gauges the resilience of past small-scale productive systems and can potentially help shape future strategies for communities in the present."

Source: University College London [May 09, 2019]

Artificial intelligence for studying the ancient human populations of Patagonia

By: Thomas Schmitt Attorney on December 03, 2018 / comment : 0 Americas, Archaeology, Patagonia, South America

Argentine and Spanish researchers have used statistical techniques of automatic learning to analyze mobility patterns and technology of the hunter-gatherer groups that inhabited the Southern Cone of America, from the time they arrived about 12,000 years ago until the end of the 19th century. Big data from archaeological sites located in the extreme south of Patagonia have been used for this study.

Atlantic Coast of Isla Grande de Tierra del Fuego, Punta Torcida sector [Credit: Ivan Briz i Godino]

The presence of humans on the American continent dates back to at least 14,500 years ago, according to datings made at archaeological sites such as Monte Verde, in Chile's Los Lagos Region. But the first settlers continued moving towards the southernmost confines of America.

Now, researchers from Argentina's National Council for Scientific and Technical Research (CONICET) and two Spanish institutions (the Spanish National Research Council and the University of Burgos) have analyzed the relationships between mobility and technology developed by those societies that originated in the far south of Patagonia.

Selk'nam people, an example of a more pedestrian group, without nautical technology, although the marine resources were intensely exploited by those who lived near the coast [Credit: C. W. Furlong (January 1908)/ End of the World Museum (Ushuaia, Argentina)]

The study, published in the Royal Society Open Science journal, is based on an extensive database of all available archaeological evidence of human presence in this region, from the time the first groups arrived in the early Holocene (12,000 years ago) until the end of the 19th century.

This was followed by the application of machine learning techniques, a statistical system that allows the computer to learn from many data (in this case, big data from characteristic technological elements of the sites) in order to carry out classifications and predictions.

Example of a group with nautical technology: Yámana people in the Anglican mission of Bahía Tekenika (Tierra del Fuego),  portrayed in the late 19th or early 20th century. Darwin lived with them during the second voyage of the Beagle [Credit: Ivan Briz i Godino/Archives of the South American Missionary Society (United Kingdom)]

"It is by means of automatic classification algorithms that we have identified two technological packages or 'landscapes': one that characterizes pedestrian hunter-gatherer groups (with their own stone and bone tools) and the other characterizing those that had nautical technology, such as canoes, harpoons and mollusc shells used to make beads," explains Ivan Briz i Godino, an archaeologist of the National Council for Scientific and Technical Research (CONICET) of Argentina and co-author of the work.

"In future excavations, when sets of technological elements such as those we have detected appear, we'll be able to directly deduce the type of mobility of the group or the connections with other communities," adds Briz.

Technological landscapes of nautical mobility (red circles, with some blues that are less well classified by the algorithm) and pedestrian mobility (orange and purple circles) in hunter-gatherer groups that lived  in the extreme south of South America [Credit: Briz et al. 2018]

The results of the study have also made it possible to obtain maps with the settlements of the two communities, and this, in turn, has made it possible to locate large regions in which they interacted and shared their technological knowledge. In the case of groups with nautical technology, it has been confirmed that they arrived at around the beginning of the Mid-Holocene (some 6,000 years ago) from the channels and islands of the South Pacific, moving along the coast of what is now Chile.

"Traditional archaeology identifies sites, societies and their possible contacts on the basis of specific elements selected by specialists (such as designs of weapon tips or decorative elements), but here we show that it is more interesting to analyse sets of technological elements as a whole, using artificial intelligence techniques that allow us to work with large data volumes and without subjective prejudices," concludes Briz.

Source: FECYT - Spanish Foundation for Science and Technology [December 03, 2018]

A new study to improve seabird conservation in Patagonian ecosystems

By: Thomas Schmitt Attorney on July 04, 2018 / comment : 0 Biodiversity, Natural Heritage, Patagonia, Wildlife

Preserving a 300,000 square km area in Patagonian waters could improve the conservation of 20 % of the population of sea birds in their natural habitat, according to a study published in the journal Conservation Biology and led by the expert Francisco Ramírez, researcher from the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio).

The new study opens a new view to identify key areas for the conservation of seabirds in one of the most emblematic and productive natural systems of the world [Credit: Massimiliano Drago, UB-IRBio]

The new study, which shows a multidisciplinary approach to define marine areas of interest in conservation, is also signed by Isabel Afán, Joan Giménez and Manuela G. Forero, from the Doñana Biological Station (EBD-CSIC).

One of the marine ecosystems with more biodiversity worldwide

Only 3 % of the ocean surface is protected, which is a lower level to the one in terrestrial ecosystems. Marine ecosystems in the Argentinian Patagonia are one of the areas with a larger biodiversity and highest biological production worldwide. Despite their ecological value, they are now one of the most threatened marine areas by the impact of human activity -intense fishing activity- and changes related to global warming.

At the moment, seabirds are the most threatened bird group worldwide. As part of this research, experts studied the populations of fourteen species of seabirds distributed over 3,000 kilometres in the Patagonian coast. Among the most threatened seabirds are the Olrog's Gull (Larus atlanticus), the red-legged cormorant (Phalacrocorax gaimardi) and the Magellanic penguin (Spheniscus magellanicus), according to the recent reports by the International Union for Conservation of Nature (IUCN).

Environmental conservation: oceanic dynamics matter

In general, the delimitation in protected marine areas is based on the experts' criteria on the material and data of the distribution of some species which are especially threatened. The new study opens a new view to identify key areas for the conservation of seabirds in one of the most emblematic and productive natural systems of the world.

According to Francisco Ramírez, from the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB and IRBio, "in our study, we carried out a modelling of the spatial distribution of more than two million seabirds of fourteen different species. With these data, we identified the areas that allow us to protect at least a 20 % of these populations through the application of preservation measures".

This is one of the first studies to consider the effect of ocean currents in the planning of preserved marine areas. According to Isabel Afán, "if we consider the marine current system of the area, there are other areas that are connected to the priority areas to be protected which are also important regarding management, since they can bring environment alterations to the priority areas. For instance, in accident cases such as ocean dumpings, it is important to know the areas that could bring the risk products to protected areas, and therefore, apply some management measure on these areas".

The new study to delimit protection areas in Patagonian regions takes into account the protected marine regions that were proposed by BirdLife International, and based on the spatial distribution of pelagic seabirds. However, these species nest outside the Patagonian coasts and visit the marine regions to get food, experts warn. Therefore, apart from including BirdLife's suggestions, the new study adds a set of coastal areas to improve the conservation of fourteen species that breed around the Patagonian coasts.

Protecting oceans for a more sustainable future

People are more and more aware -thanks to international organisms- of the need to find a balance between environmental protection in the oceans and high socioeconomic impact activities (fisheries, leisure activities, etc.). The methodology that was published in Conservation Biology could be applied to marine ecosystems where researchers know about the spatial distribution of breeding colonies of seabirds and the amount of individuals per colony.

Since the marine environment is a broad and dynamic scenario, and hard to access, "it is necessary to review the suggested protected marine areas to improve environmental management tools. Therefore, this is a dynamic and adaptive process which should count on all the involved stakeholders, from fishermen to conservationist entities", concludes the researcher Francisco Ramírez.

Source: University of Barcelona [July 04, 2018]