Cornell research traces how farmlands affect bee disease spread

CORNELL UNIVERSITY

 

IMAGE: A SWEAT BEE FORAGES ON GOLDENROD. view more 

CREDIT: LAURA FIGUEROA, CORNELL UNIVERSITY

ITHACA, N.Y. - A new Cornell University study on bees, plants and landscapes in upstate New York sheds light on how bee pathogens spread, offering possible clues for what farmers could do to improve bee health.

The study, "Landscape Simplification Shapes Pathogen Prevalence in Plant-Pollinator Networks," which used empirical data and mathematical modeling, reveals how surrounding landscapes might affect the ways that bees and flowers interact, and how interconnected networks of plants and pollinators influence disease spread in bees. The findings are important because bee diseases have contributed to pollinator declines worldwide.

"Our results are telling us that we need to think about [bee, flower, pathogen and landscape] interactions," said Laura Figueroa, the paper's lead author and a doctoral student in the lab of Scott McArt, assistant professor of entomology.

The study found that 65% of bee species and 75% of flower species carried pathogens, and that pathogens are transmitted between bees and flowers.

Figueroa and colleagues began with an empirical study of the bee species present on wildflower strips in upstate New York. In 2012, the researchers began planting uniform plots of wildflowers on 11 sites with varying amounts of surrounding farmland. In 2015, the team observed, tracked and recorded which bee species visited which flowers, ultimately describing the interaction patterns of 46 bee species and 13 plant species. They found that the common eastern bumblebee, as the dominant bee species in upstate New York, has a greater influence than other species on disease transmission dynamics.

The researchers also collected bees and flowers from each site and screened them for pathogens in the lab.

"In more simplified landscapes [with more farmland], the dominant species visited more plant species," Figueroa said.

This study found the bumblebees' increased diet breadth spread pathogens across many more flowers, she said, which in turn reduced each individual bee's exposure to new pathogens.

The researchers then entered the data from their empirical study into a mathematical model. They found that on a community level, accounting for all bee and flower species, the likelihood of a communitywide outbreak of disease decreased when the network of flowers and bees was highly interconnected, again, because pathogens were diluted across more flowers.

This is especially important when farmers plant wildflower strips to improve pollinator health.

While simple farm landscapes might lower disease spread on a communitywide level, each individual species behaves differently, depending on which flowers they visit, and which pathogens affect them. Future studies will parse out how individual species fare in simplified landscapes, which has important conservation implications.

"Potentially," Figueroa said, "we could develop mixtures of wildflower species that can not only maximize food for the pollinators, but can shape interactions in a way that reduce the likelihood of disease spread."

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The study was supported by the National Institutes of Health, the National Science Foundation, the U.S. Department of Agriculture, the Garden Club of America and the Cornell Atkinson Center for Sustainability.

Saving livestock by thinking like a predator

Preventing endangered carnivores from eating valuable livestock may require going back to Ecology 101

UNIVERSITY OF CALIFORNIA - BERKELEY

IMAGE: A NEW STUDY BY UNIVERSITY OF CALIFORNIA, BERKELEY, RESEARCHERS, ARGUES THAT EFFECTIVELY REDUCING ENCOUNTERS BETWEEN DOMESTIC PREY AND WILD PREDATORS REQUIRES KNOWING THE PRINCIPLES GOVERNING THE ECOLOGICAL INTERACTIONS AMONG THESE... view more 

CREDIT: PHOTO BY CHRISTINE WILKINSON, FUNDED BY THE NATIONAL GEOGRAPHIC SOCIETY

Berkeley -- For predators like wolves, cougars and snow leopards, a cow or sheep out to pasture may make for an easy and tasty meal. But when wild animals eat livestock, farmers face the traumatic loss of food or income, frequently sparking lethal conflicts between humans and their carnivorous neighbors.

Humans have struggled to reduce the loss of livestock to carnivores for thousands of years, and yet, solutions remain elusive. According to a new study led by researchers at the University of California, Berkeley, solving this ancient puzzle requires going back to Ecology 101.

Effectively reducing encounters between domestic prey and wild predators, the researchers argue, requires knowing the principles governing the ecological interactions among these players and their surrounding landscape. Simply put, getting in the mind of predators -- considering the ecology of how they hunt, how their prey behaves and how they interact with the landscape around them -- will help farmers and wildlife managers target interventions to discourage wild carnivores from preying on valuable livestock.

"There is no 'one-size-fits-all' solution for livestock predation, because the variables at play change, depending on the stakeholders, the landscape and the carnivores and livestock involved -- as well the scale and cost of management tools," said Christine Wilkinson, a graduate student in environmental science, policy and management at UC Berkeley and lead author on the study, which appeared this week in the journal Conservation Biology. "But at the core of the problem is an ecological act: predation."

In addition to lethal means of warding off potential predators, like poisoning or hunting, a variety of nonlethal deterrents are available. Guardian dogs, lights, electric fencing or bright-colored flags can all keep carnivores at bay while preserving the local ecology. Other strategies, like regularly moving livestock to different pastures or keeping them inside an enclosure at night, can make it harder for carnivores to locate and hunt them.

But the same techniques that prevent wolves from eating sheep in the rocky valleys of Idaho may not be as effective at preventing snow leopards from killing livestock in the high elevations of the Himalayas. Instead of focusing on the overall effectiveness of any one technique, the authors urge wildlife managers to approach the problem by considering a framework that includes the carnivore ecology, the livestock ecology and how the two species interact with the landscape around them.

"By knowing the full ecological story, we can tinker with the tools in our management toolkit to keep both predators and livestock safe," said Defenders of Wildlife senior scientist and co-author Jennie Miller.

For instance, wolves are known to be afraid of strings of red flags called fladry, and using fladry around a pasture might be a cost-effective method for keeping the predators away from sheep. But considering other aspects of the ecology, such as where the pastures are located, or where the sheep are kept at night, could yield even better results, depending on context.

These strategic combinations of deterrents have successfully kept predators at bay in a variety of settings, the paper points out. The authors highlight three case studies from around the world, demonstrating the success that can occur when ecology is the foundation of targeted interventions, and the failure that can occur when it is ignored.

The study's framework provides guidance for livestock managers to consider their management techniques as a component of livestock ecology. "Livestock have, in some sense, been bred to be an easy target for carnivores," Wilkinson said. "Humans have to recreate the defenses that we bred away."

The next step for

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the researchers is applying this framework to provide livestock managers with concrete tools to mitigate conflict as part of a larger, collaborative research and outreach effort based in the Brashares Group at UC Berkeley.

The interdisciplinary team of co-authors on the paper also included Alex McInturff, Veronica Yovovich, Kaitlyn Gaynor, Kendall Calhoun, Harshad Karandikar, Jeff Vance Martin, Phoebe Parker-Shames, Avery Shawler, Amy Van Scoyoc and, senior author, Justin Brashares of UC Berkeley.

This research was supported by a National Science Foundation Graduate Research Fellowship and National Geographic Society grant 466 WW-100C-17.

A new study by University of California, Berkeley, researchers, argues that effectively reducing encounters between domestic prey and wild predators requires knowing the principles governing the ecological interactions among these players and their surrounding landscape. In some cases, predator-proof enclosures, like this one in Soysambu Conservancy, Kenya, can be an effective element in a broader management strategy.

CREDIT Photo by Christine Wilkinson, funded by the National Geographic Society

Researchers reveal largest and hottest shield volcano on Earth

UNIVERSITY OF HAWAII AT MANOA

 

IMAGE: THE ONLY REMNANTS OF PŪHĀHONU THAT ARE ABOVE SEA LEVEL (GARDNER PINNACLES). view more 

CREDIT: NOAA

In a recently published study, researchers from the University of Hawai'i at Mānoa School of Ocean and Earth Science and Technology revealed the largest and hottest shield volcano on Earth. A team of volcanologists and ocean explorers used several lines of evidence to determine Pūhāhonu, a volcano within the Papahānaumokuākea Marine National Monument now holds this distinction.

Geoscientists and the public have long thought Mauna Loa, a culturally-significant and active shield volcano on the Big Island of Hawai'i, was the largest volcano in the world. However, after surveying the ocean floor along the mostly submarine Hawaiian leeward volcano chain, chemically analyzing rocks in the UH Mānoa rock collection, and modeling the results of these studies, the research team came to a new conclusion. Pūhāhonu, meaning 'turtle rising for breath' in Hawaiian, is nearly twice as big as Mauna Loa.

"It has been proposed that hotspots that produce volcano chains like Hawai'i undergo progressive cooling over 1-2 million years and then die," said Michael Garcia, lead author of the study and retired professor of Earth Sciences at SOEST. "However, we have learned from this study that hotspots can undergo pulses of melt production. A small pulse created the Midway cluster of now extinct volcanoes and another, much bigger one created Pūhāhonu. This will rewrite the textbooks on how mantle plumes work."  

In 1974, Pūhāhonu (then called Gardner Pinnacles) was suspected as the largest Hawaiian volcano based on very limited survey data. Subsequent studies of the Hawaiian Islands concluded that Mauna Loa was the largest volcano but they included the base of the volcano that is below sea level that was not considered in the 1974 study. The new comprehensive surveying and modeling, using methods similar to those used for Mauna Loa show that Pūhāhonu is the largest.

This study highlights Hawaiian volcanoes, not only now but for millions of years, have been erupting some of the hottest magma on Earth. This work also draws attention to an infrequently visited part of the state of Hawai'i that has ecological, historical and cultural importance.

"We are sharing with the science community and the public that we should be calling this volcano by the name the Hawaiians have given to it, rather than the western name for the two rocky small islands that are the only above sea level remnants of this once majestic volcano," said Garcia.

Shorelines of modern-day Hawai'i Island (5 volcanoes) compared to ancient P?hāhonu (1 volcano).

A lost world and extinct ecosystem

ARIZONA STATE UNIVERSITY

IMAGE: LOOKING OUT AT THE PALAEO-AGULHAS PLAIN FROM THE CAVE ENTRANCE AT THE PINNACLE POINT, SOUTH AFRICA, RESEARCH SITE--LEFT, 200,000 YEARS AGO DURING GLACIAL PHASES AND LOWER SEA LEVELS, AND RIGHT,... view more 

CREDIT: ERICH FISHER

Archaeological sites on the far southern shores of South Africa hold the world's richest records for the behavioral and cultural origins of our species. At this location, scientists have discovered the earliest evidence for symbolic behavior, complex pyrotechnology, projectile weapons and the first use of foods from the sea.

The Arizona State University Institute of Human Origins (IHO) field study site of Pinnacle Point sits at the center of this record, both geographically and scientifically, having contributed much of the evidence for these milestones on the evolutionary road to being a modern human.

The scientists working on these sites, led by IHO Associate Director Curtis Marean, have always faced a dilemma in understanding the context of these evolutionary milestones -- much of the landscape used by these ancient people is now submerged undersea and thus poorly known to us. Marean is a Foundation Professor with the ASU School of Human Evolution and Social Change and Honorary Professor with Nelson Mandela University in South Africa.

The archaeological records come from caves and rockshelters that now look out on to the sea, and in fact, walking to many of the sites today involves dodging high tides and waves. However, through most of the last 200,000 years, lowered sea levels during glacial phases, when the ice sucks up the water, exposed a vast plain. The coast was sometimes as much as 90 km distant! Our archaeological data shows that this was the prime foraging habitat for these early modern humans, and until recently, we knew nothing about.

That has now changed with the publication of 22 articles in a special issue of Quaternary Science Reviews titled "The Palaeo-Agulhas Plain: A lost world and extinct ecosystem." About ten years ago, Marean began building a transdisciplinary international team to tackle the problem of building an ecology of this ancient landscape. ASU, Nelson Mandela University, the University of Cape Town, and the University of California, Riverside anchored the research team. Funded primarily by a $1 million National Science Foundation grant to Marean, with significant funding and resources from the Hyde Family Foundations, the John Templeton Foundation, ASU, IHO, and XSEDE, they developed an entirely new way to reconstruct "paleoecologies" or ancient ecosystems.

This began with using the high-resolution South African regional climate model -- running on U.S. and South African supercomputers -- to simulate glacial climate conditions. The researchers used this climate output to drive a new vegetation model developed by project scientists to recreate the vegetation on this paleoscape. They then used a wide variety of studies such as marine geophysics, deep-water diving for sample collection, isotopic studies of stalagmites and many other transdisciplinary avenues of research to validate and adjust this model output. They also created a human "agent-based model" through modern studies of human foraging of plants, animals, and seafoods, simulating how ancient people lived on this now extinct paleoscape.

"Pulling the threads of all this research into one special issue illustrates all of this science," said Curtis Marean. "It represents a unique example of a truly transdisciplinary paleoscience effort, and a new model for going forward with our search to recreate the nature of past ecosystems. Importantly, our results help us understand why the archaeological records from these South African sites consistently reveal early and complex levels of human behavior and culture. The Palaeo-Agulhas Plain, when exposed, was a 'Serengeti of the South"' positioned next to some of the richest coastlines in the world. This unique confluence of food from the land and sea cultivated the complex cultures revealed by the archaeology and provided safe harbor for humans during the glacial cycles that revealed that plain and made much of the rest of the world unwelcoming to human life."

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Access to the special issue can be found here: https://www.sciencedirect.com/journal/quaternary-science-reviews/vol/235/suppl/C

Washington Post's depictions of autism shift from 'cause and cure' to acceptance

Study reviews 315 articles published from 2007 to 2017

UNIVERSITY OF CALIFORNIA - SANTA CRUZ

The Washington Post's depiction of autism has shifted over the years from a focus on "cause and cure" toward one of acceptance and accommodation, say the authors of a study that examined 315 articles published from 2007 to 2017.

The findings, which appear in the current online edition of Disability and Society, suggest that media representations are changing to reflect new public attitudes generated in part by the autistic rights movement, say co-authors Noa Lewin, a 2018 graduate of the University of California, Santa Cruz, and Nameera Akhtar, a professor of psychology at UCSC.

"There's less focus on cause and a bigger focus on accommodation," said Lewin, whose undergraduate senior thesis was the basis of the study. "Coverage has shifted more toward how to make life better for autistic people and less on what is causing autism."

The paper, "Neurodiversity and Deficit Perspectives in the Washington Post's Coverage of Autism," is based on a content analysis of coverage beginning in 2007, before the putative link between the MMR vaccine and autism had been completely debunked. It ends 10 years later, when the neurodiversity rights movement had advanced understanding and awareness about the range of ways brains function and that variations from "normal" are not necessarily deficits. The researchers chose to examine the influential Washington Post because it is widely read by legislators and policy makers.

Akhtar, the corresponding author of the paper, is at the forefront of paradigm-shifting scholarship about autism and has called for greater understanding of autism. "The autism self-advocacy movement has been around for a while, but the idea that autism is something that should be accommodated rather than 'cured' is new for people who haven't been exposed to it," she said.

In their analysis, Lewin and Akhtar found that the Post's articles over time were more likely to talk about "neurodiversity" and to acknowledge the strengths of autistic people. Articles also began to describe accommodations for autistic people, and a few began to feature the voices of autistic people themselves--a trend Lewin, who is autistic, particularly appreciated.

"I remember one article about autism-related legislation that quoted a member of the Autistic Self-Advocacy Network (ASAN)," said Lewin, who links the increased visibility of people with autism to the broader disability-rights movement. "We tend to think of a disability as a medical tragedy, and we don't think about how attitudes, systemic ableism, and barriers contribute to that."

Although the paper's coverage over time gradually placed more emphasis on autistic skills and strengths, coverage continued to use negative terms to describe autistic people. For example, the terms "high functioning" and "low functioning" continue to appear, despite autistic advocates' preference for more specific language, such as "speaking" and "non-speaking." And the emphasis on strengths was on autistic people who can do things like speak conversationally and hold jobs.

"The Post's coverage reflected a widespread belief that having a disability is okay if you're able to fit into a neurotypical world or if it offers a special talent or skill with social value, like being really good with computers," said Lewin.

Akhtar is pleased to see media representations of autism changing, and she was delighted to collaborate with Lewin on the paper. "Autistic people should be involved in research about autism," she said. "I was happy to work with Noa and to gain this insider's perspective. I learned a lot. You learn to broaden your way of thinking by interacting with people with different experiences."

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Social good creates economic boost

As governments around the globe move to prop up their ailing economies, a first-of-its-kind investigation could provide important input to employment policy

QUEENSLAND UNIVERSITY OF TECHNOLOGY

 

IMAGE: QUT'S PROFESSOR PER DAVIDSSON AND PROFESSOR MARTIN OBSCHONKA view more 

CREDIT: QUT

As unemployment rates skyrocket around the world in response to the COVID-19 pandemic, a world-first study has found social venture start-ups not only alleviate social problems but also are much more important for job creation than previously thought.

Written by Professor Martin Obschonka, Director of QUT's Australian Centre for Entrepreneurship Research, and its founding director, Professor Per Davidsson, along with collaborators from Sweden, the paper - The regional employment effects of new social firm entry - has just been published on Springer Open Access.

They contend the impact of social venture start-ups on regional job creation has been largely overlooked. They also argue the first-of-its-kind investigation could provide important input to employment policy, especially as global governments scramble to prop up ailing economies.

"It has long been acknowledged that the entry and growth of new firms contribute a large share of job creation in most countries. Social venture start-ups, however, are mostly celebrated for their worth in helping the disadvantaged or solving social concerns - their role in job creation has not really been considered," said Professor Obschonka.

"Yet using an established method for tracking direct and indirect job creation effects across 67 regions in Sweden over an eight-year period from start-up entry into the marketplace, our findings show the average job creation effect per firm was larger for social start-ups than for their commercial counterparts.

"Job creation is often a major focus of the social mission of these start-ups, especially for marginalised groups including people with disabilities and long-term unemployed individuals."

Professor Davidsson said the findings were contrary to the reliance on volunteers by many social endeavours.

"There appear to be a number of reasons social ventures create more jobs. First up, most 'commercial' start-ups represent individuals choosing self-employment which can mean they have no burning desire to grow and take on employees," Professor Davidsson said.

"Commercial start-ups also often operate in crowded markets with little room for growth. So even the high growth firms among the commercial category do not raise the average to high levels; partly because they outcompete or acquire some of their peers.

"By contrast, social ventures address underserved 'markets' of social problems, such as homelessness, substance abuse, domestic violence, refugees, environmental concerns, animal shelters, foodbanks, crisis centres, youth unemployment and so on.

"This creates room for growth without pushing out other social ventures. And being passionate about solving as much of 'their' social issue as they possibly can, social entrepreneurs are motivated to grow.

"They can also benefit from lower costs due to tax breaks and partial reliance on volunteers to have a growth advantage over commercial firms offering competing products or services."

The authors of the study acknowledge that as the commercial firm sector is much larger than the social sector, total job creation is greater overall.

The study compared regions in Sweden in terms of their social and commercial start-ups between 1990 to 2014 and their net job creation effects in each up to eight years after they entered the market.

"Similar comparisons for Australia or other countries do not yet exist," said Professor Obschonka.

"However, total employment in the social sector has grown recently in other countries, so our findings would most likely be valid in Australia and elsewhere along with Sweden."

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View the full paper online at Springer Open Access.

Media contact:

Amanda Weaver, QUT Media, 07 3138 3151, amanda.weaver@qut.edu.au

After hours: Rose Trapnell, 0407 585 901, media@qut.edu.au

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy 

Modern sea-level rise linked to human activities, Rutgers research reaffirms

Surprising glacial and nearly ice-free periods in last 66 million years

RUTGERS UNIVERSITY

IMAGE: SCIENTISTS BOARDING THE D/V JOIDES RESOLUTION OFF NEW JERSEY IN 1993. THE SEA LEVEL IN AN ICE-FREE WORLD WOULD BE 66 METERS (216.5 FEET) HIGHER THAN NOW - SHOULDER-HIGH TO... view more 

CREDIT: KENNETH G. MILLER, JAMES V. BROWNING AND GREGORY S. MOUNTAIN

New research by Rutgers scientists reaffirms that modern sea-level rise is linked to human activities and not to changes in Earth's orbit.

Surprisingly, the Earth had nearly ice-free conditions with carbon dioxide levels not much higher than today and had glacial periods in times previously believed to be ice-free over the last 66 million years, according to a paper published in the journal Science Advances.

"Our team showed that the Earth's history of glaciation was more complex than previously thought," said lead author Kenneth G. Miller, a Distinguished Professor in the Department of Earth and Planetary Sciences in the School of Arts and Sciences at Rutgers University-New Brunswick. "Although carbon dioxide levels had an important influence on ice-free periods, minor variations in the Earth's orbit were the dominant factor in terms of ice volume and sea-level changes - until modern times."

Sea-level rise, which has accelerated in recent decades, threatens to permanently inundate densely populated coastal cities and communities, other low-lying lands and costly infrastructure by 2100. It also poses a grave threat to many ecosystems and economies.

The paper reconstructed the history of sea levels and glaciation since the age of the dinosaurs ended. Scientists compared estimates of the global average sea level, based on deep-sea geochemistry data, with continental margin records. Continental margins, which include the relatively shallow ocean waters over a continental shelf, can extend hundreds of miles from the coast.

The study showed that periods of nearly ice-free conditions, such as 17 million to 13 million years ago, occurred when the concentration of atmospheric carbon dioxide - a key greenhouse gas driving climate change - was not much higher than today. However, glacial periods occurred when the Earth was previously thought to be ice-free, such as from 48 million to 34 million years ago.

"We demonstrate that although atmospheric carbon dioxide had an important influence on ice-free periods on Earth, ice volume and sea-level changes prior to human influences were linked primarily to minor variations in the Earth's orbit and distance from the sun," Miller said.

The largest sea-level decline took place during the last glacial period about 20,000 years ago, when the water level dropped by about 400 feet. That was followed by a foot per decade rise in sea level - a rapid pace that slowed from 10,000 to 2,000 years ago. Sea-level rise was then at a standstill until around 1900, when rates began rising as human activities began influencing the climate.

Future work reconstructing the history of sea-level changes before 48 million years ago is needed to determine the times when the Earth was entirely ice-free, the role of atmospheric carbon dioxide in glaciation and the cause of the natural fall in atmospheric carbon dioxide before humans.

Rutgers coauthors include Professor James V. Browning, doctoral student W. John Schmelz and professors Robert E. Kopp, Gregory S. Mountain and James D. Wright, the senior author of the study.

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Global cooling event 4,200 years ago spurred rice's evolution, spread across Asia

Scientists use genomics, archeology, and climate data to reconstruct history of rice

NEW YORK UNIVERSITY

IMAGE: A SIMPLIFIED MAP SHOWS THE SPREAD OF RICE INTO BOTH NORTHERN AND SOUTHERN ASIA FOLLOWING A GLOBAL COOLING EVENT APPROXIMATELY 4,200 YEARS BEFORE PRESENT (YBP). view more 

CREDIT: RAFAL GUTAKER, NEW YORK UNIVERSITY

A major global cooling event that occurred 4,200 years ago may have led to the evolution of new rice varieties and the spread of rice into both northern and southern Asia, an international team of researchers has found.

Their study, published in Nature Plants and led by the NYU Center for Genomics and Systems Biology, uses a multidisciplinary approach to reconstruct the history of rice and trace its migration throughout Asia.

Rice is one of the most important crops worldwide, a staple for more than half of the global population. It was first cultivated 9,000 years ago in the Yangtze Valley in China and later spread across East, Southeast, and South Asia, followed by the Middle East, Africa, Europe, and the Americas. In the process, rice evolved and adapted to different environments, but little is known about the routes, timing, and environmental forces involved in this spread.

In their study, the researchers reconstructed the historical movement of rice across Asia using whole-genome sequences of more than 1,400 varieties of rice--including varieties of japonica and indica, two main subspecies of Asian rice--coupled with geography, archaeology, and historical climate data.

For the first 4,000 years of its history, farming rice was largely confined to China, and japonica was the subspecies grown. Then, a global cooling event 4,200 years ago--also known as the 4.2k event, which is thought to have had widespread consequences, including the collapse of civilizations from Mesopotamia to China--coincided with japonica rice diversifying into temperate and tropical varieties. The newly evolved temperate varieties spread in northern China, Korea and Japan, while the tropical varieties and spread to Southeast Asia.

"This abrupt climate change forced plants, including crops, to adapt," said Rafal M. Gutaker, a postdoctoral associate at the NYU Center for Genomics and Systems Biology and the study's lead author. "Our genomic data, as well as paleoclimate modeling by our collaborators, show that the cooling event occurred at the same time as the rise of temperate japonica, which grows in milder regions. This cooling event also may have led to the migration of rice agriculture and farmer communities into Southeast Asia."

"These findings were then backed up by data from archaeological rice remains excavated in Asia, which also showed that after the 4.2k event, tropical rice migrated south while rice also adapted to northern latitudes as temperate varieties," said Michael D. Purugganan, the Silver Professor of Biology at NYU, who led the study.

After the global cooling event, tropical japonica rice continued to diversify. It reached islands in Southeast Asia about 2,500 years ago, likely due to extensive trade networks and the movement of goods and peoples in the region--a finding also supported by archeological data.

The spread of indica rice was more recent and more complicated; after originating in India's lower Ganges Valley roughly 4,000 years ago, the researchers traced its migration from India into China approximately 2,000 years ago.

While the researchers had thought that rainfall and water would be the most limiting environmental factor in rice diversity, they found temperature to be the key factor instead. Their analyses revealed that heat accumulation and temperature were very strongly associated with the genomic differences between tropical and temperate japonica rice varieties.

"This study illustrates the value of multidisciplinary research. Our genomic data gave us a model for where and when rice spread to different parts of Asia, archaeology told us when and where rice showed up at various places, and the environmental and climate modeling gave us the ecological context," said Purugganan. "Together, this approach allows us to write a first draft of the story of how rice dispersed across Asia."

Understanding the spread of rice and the related environmental pressures could also help scientists develop new varieties that meet future environmental challenges, such as climate change and drought--which could help address looming food security issues.

"Armed with knowledge of the pattern of rice dispersal and environmental factors that influenced its migration, we can examine the evolutionary adaptations of rice as it spread to new environments, which could allow us to identify traits and genes to help future breeding efforts," said Gutaker.

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In addition to Purugganan and Gutaker, study authors include other members of the Purugganan laboratory at the NYU Center for Genomics and Systems Biology, and collaborators at Pennsylvania State University, Universidade Nova de Lisboa in Portugal, the Crow Canyon Archaeological Center, Carnegie Mellon University, the University of Manitoba, University College London, North-West University in China, University College Dublin, and the University of California San Diego.

The research at NYU was supported by the Zegar Family Foundation and the National Science Foundation Plant Genome Research Program (IOS-1546218).

RELEASE 15-MAY-2020

Early humans thrived in this drowned South African landscape

The Paleo-Agulhas Plain had diverse, verdant ecosystems and abundant game

UNIVERSITY OF CALIFORNIA - RIVERSIDE

Early humans lived in South African river valleys with deep, fertile soils filled with grasslands, floodplains, woodlands, and wetlands that abounded with hippos, zebras, antelopes, and many other animals, some extinct for millennia.

In contrast to ice age environments elsewhere on Earth, it was a lush environment with a mild climate that disappeared under rising sea levels around 11,500 years ago.

An interdisciplinary, international team of scientists has now brought this pleasant cradle of humankind back to life in a special collection of articles that reconstruct the paleoecology of the Paleo-Agulhas Plain, a now-drowned landscape on the southern tip of Africa that was high and dry during glacial phases of the last 2 million years.

"These Pleistocene glacial periods would have presented a very different resource landscape for early modern human hunter-gatherers than the landscape found in modern Cape coastal lowlands, and may have been instrumental in shaping the evolution of early modern humans," said Janet Franklin, a distinguished professor of biogeography in the department of Botany and Plant Sciences at UC Riverside, an associate member of the African Centre for Coastal Palaeoscience at Nelson Mandela University in South Africa, and co-author of several of the papers.

Some of the oldest anatomically modern human bones and artifacts have been found in cliff caves along the coast of South Africa. For many years, the lack of shellfish in some layers at these sites puzzled archaeologists. In spite of apparently living near the ocean, the inhabitants hunted mostly big game -- the sort of animals that typically live farther inland.

Scientists knew a submerged landscape existed on the continental shelf just offshore, but it wasn't until recently, perhaps inspired by rising sea levels of our current human-caused global warming, they realized these caves might have made up the westernmost edge of a long-lost plain.

During most of the Pleistocene, the geological era before the one we live in now, these caves were not located on the coast. With so much of the Earth's water locked up in continent-sized glaciers, sea level was much lower, and humans could have thrived between the cliffs and a gentler coastline miles and miles to the east.

A special issue of Quaternary Science Reviews presents papers using a wide range of techniques to reconstruct the environment and ecology of the Paleo-Agulhas Plain. They reveal a verdant world rich with game, plant, and coastal resources, periodically cut off from the mainland during warm spells between glacial periods when sea level rose to levels similar to those of today, which would have played an important role in human evolution.

Franklin and her colleagues used modern vegetation patterns along the Cape south coast to develop models of the expected vegetation for the various soil types, as well as the climate (especially rainfall) and fire regimes of the past glacial periods that framed most of the timeframe in which modern humans emerged.

Joining her in the research were Richard M. Cowling and Alastair J. Potts of Nelson Mandela University; Guy F. Midgley at Stellenbosch University; Francois Engelbrecht of the University of Witwatersrand; and Curtis W. Marean of Arizona State University.

Vegetation was reconstructed based on a model of the ancient climate and fire patterns of these glacial phases that define human evolution. The group developed the vegetation model based on present-day patterns and environmental conditions, compared their model to an independently derived vegetation map to validate it, then applied it to the climate, landforms, and soils reconstructed for the peak of the last ice age on the Palaeo-Agulhas Plain.

Reconstruction, mapping, and modeling of the paleo-climate, geology, and soils by their collaborators are featured in other articles in the special issue.

The model found the paleo-landscape exposed during glacial low-sea levels added a land area the size of Ireland to the southern tip of Africa. Near the coast, it was dominated by "limestone fynbos," a low-stature, but species-rich shrubland typical of contemporary South Africa's Cape Floristic Province, a global plant diversity hotspot. The northern plains were mostly grasslands in shallow floodplains and on shale bedrock.

This savanna-like vegetation is rare in the modern landscape and would have supported the megafauna typical of glacial periods. These game animals, found in the archaeological record, include a great diversity of grazing animals, including the now-extinct giant Cape Buffalo, and others of which no longer occur naturally in this part of Africa, such as giraffes.

The Paleo-Agulhas plain had extremely high plant species diversity, as well as a greater variety of ecosystems and plant communities than currently found in this region, including shale grassland with dune fynbos-thicket mosaic on uplands and broad and shallow floodplains supporting a mosaic of woodland and grassland on fertile, alluvial soils.

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This research is published as, "Describing a drowned Pleistocene ecosystem: Last Glacial Maximum vegetation reconstruction of the Palaeo-Agulhas Plain."

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How do plants forget?

An international group of researchers found the answer to the question: How do plants forget?

INSTITUTO GULBENKIAN DE CIENCIA

The study now published in Nature Cell Biology reveals more information on the capacity of plants, identified as 'epigenetic memory,' which allows recording important information to, for example, remember prolonged cold in the winter to ensure they flower at the right time during the spring.

As soon as they produce seeds, this information is "erased" from memory so they don't bloom too early the following winter.

Although they do it differently than humans, plants also have memories. This so-called "epigenetic memory" occurs by modifying specialized proteins called histones, which are important for packaging and indexing DNA in the cell. One such histone modification, called H3K27me3, tends to mark genes that are turned off. In the case of flowering, cold conditions cause H3K27me3 to accumulate at genes that control flowering. Previous work from the Berger lab has shown how H3K27me3 is faithfully transmitted from cell to cell so that in the Spring, plants will remember that it was cold and that winter is over, allowing them to flower at the right time. But just as importantly, once they've flowered and made seeds, the seeds need to forget this 'memory' of the cold so that they do not flower too soon once winter comes around again. Since H3K27me3 is faithfully copied from cell to cell, how do plants go about forgetting this memory in seeds?

Jörg Becker, principal investigator at the Instituto Gulbenkian de Ciência, involved in the international team led by researcher Frédéric Berger, of the Gregor Mendel Institute of the Austrian Academy of Sciences, says that researchers set out to analyse histones in pollen, hypothesizing that the process of forgetting would most likely occur in the embedded sperm. According to Jörg Becker, "the study led us to identify a phenomenon, the so-called "epigenetic resetting", akin to erasing and reformatting data on a hard drive".

The researchers were surprised to find that H3K27me3 completely disappeared in sperm. They found that sperm accumulate a special histone that is unable to carry H3K27me3. This ensures that this modification is erased from hundreds of genes, not only those that prevent flowering but also ones which control a large array of important functions in seeds, which are produced once the sperm is carried by the pollen to fuse with the plant egg cell.

This phenomenon is called "epigenetic resetting" and is akin to erasing and reformatting data on a hard drive.

"This actually makes a lot of sense from an ecological perspective" says Dr. Borg, first author of the paper. "Since pollen can spread over long distances, by wind or bees for example, and much of the "memory" carried by H3K27me3 is related to environmental adaptation, it makes sense that seeds should "forget" their dad's environment and instead remember their mother's, since they are most likely to spread and grow next to mom."

According to Dr. Berger "Like plants, animals also erase this epigenetic memory in sperm, but they do it by replacing histones with a completely different protein. This is one of the first examples of how a specialized histone variant can help reprogram and reset a single epigenetic mark while leaving others untouched. There are many more unstudied histone variants in both plants and animals, and we expect that aspects of this resetting mechanism we have discovered will be found in other organisms and developmental contexts."

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This work was carried out by an international team with members from the Gregor Mendel Institute in Austria, the Cold Spring Harbor Laboratory, Yale University, University of Kentucky, and Purdue University in the USA, Nagoya University in Japan, University of Edinburg in the UK, and the Instituto Gulbenkian Ciência in Portugal. Funding was provided by the Austrian Science Fund, ERA-CAPS, the Howard Hughes Medical Institute, NIH, the Japan Society for the Promotion of Science, the Wellcome Trust, and the European Research Council