Ocean acidification will severely impair coral reef growth before the end of the century if carbon dioxide emissions continue unchecked, according to new research on Australia's Great Barrier Reef led by Carnegie's Ken Caldeira and the California Academy of Sciences' Rebecca Albright.

Experimental set-up and research team at a coral reef flat study site at One Tree Island in Australia's Great Barrier Reef. The studies conducted here represent the first ocean acidification  experiment of a natural coral reef community, providing evidence that near-future ocean acidification projections severely depressed coral reef growth [Credit: Aaron Takeo Ninokawa of UC Davis]

Their work, published in Nature, represents the first ocean acidification experiment in which seawater was made artificially acidic by the addition of carbon dioxide and then allowed to flow across a natural coral reef community. The acidity of the seawater was increased to reflect end-of-century projections if carbon dioxide from greenhouse gas emissions are not abated.

Two years ago, Caldeira and Albright, then at Carnegie, published a landmark study providing evidence that ocean acidification is already slowing coral reef growth.

In that work, they made a coral reef community's seawater chemistry more alkaline -- essentially giving the reef an antacid -- and demonstrated that the coral's ability to construct its architecture was improved under these conditions. It was the first time that seawater chemistry was experimentally manipulated in a natural coral reef environment.

They once again altered seawater chemistry of reef flats surrounding One Tree Island off the coast of Australia. But this time they gave the reef heartburn, increasing acidity by adding carbon dioxide to seawater flowing over a coral reef community.

"Last time, we made the seawater less acidic, like it was 100 years ago, and this time, we added carbon dioxide to the water to make it more acidic, like it could be 100 years from now," Caldeira explained.

Experimental plume of carbon dioxide-enriched seawater and a dye tracer flowing across a coral reef flat in Australia's Great Barrier Reef. This study represents the first ocean acidification experiment on a natural coral reef community and provides evidence that near-future ocean acidification projections severely depressed coral reef growth [Credit: Aaron Takeo Ninokawa of UC Davis]

When coal, oil, or gas is burned, the resulting carbon dioxide is released into the atmosphere. It is well established that these emissions are the culprit of global climate change, the warming from which has a negative impact on coral reefs. But this atmospheric carbon is also absorbed into the ocean, where it remains for millennia.

A chemical reaction between the seawater and these soaked-up carbon emissions produces carbonic acid, which is corrosive to coral reefs, shellfish, and other marine life. Reefs are especially vulnerable to this ocean acidification, because their skeletons are constructed by accreting calcium carbonate, a process called calcification. As the surrounding water becomes more acidic, calcification becomes more difficult.

"Our findings provide strong evidence that ocean acidification caused by carbon dioxide emissions will severely slow coral reef growth in the future unless we make steep and rapid reductions in greenhouse gas emissions," said first author Albright.

Furthermore, by working in controlled areas of a natural reef community, Caldeira, Albright, and their team were able to demonstrate how acidification affects coral reefs on the ecosystem scale, not just in terms of individual organisms or species, as other studies have done.

They say this approach is crucial to understanding the full scope and complexity of ocean acidification's impact, as well as to predicting how acidification will affect the coastal communities that depend on these ecosystems.

"Coral reefs offer economic opportunities to their surrounding communities from fishing and tourism," Caldeira said. "But for me the reef is a beautiful and diverse outpouring of life that we are harming with our carbon dioxide emissions. For the denizens of the reef, there's not a moment to lose in building an energy system that doesn't dump its waste into the sky or sea."

Source: Carnegie Institution for Science [March 14, 2018]

A team led by scientists from Scripps Institution of Oceanography at the University of California San Diego and the J. Craig Venter Institute (JCVI) has demonstrated that the excess carbon dioxide added to the atmosphere through the combustion of fossil fuels interferes with the health of phytoplankton which form the base of marine food webs.

Photosynthetic plankton like these Ross Sea diatoms are key players in the global carbon cycle and form the base of marine food webs, but a new study reveals their ability to acquire iron is highly sensitive to ocean acidification [Credit: Jeff McQuaid]

Phytoplankton are microscopic plants whose growth in ocean surface waters supports ocean food webs and global marine fisheries. They are also key agents in the long-term removal of carbon dioxide (CO2)

As reported in the journal Nature, the team shows that a mechanism widely used by phytoplankton to acquire iron has a requirement for carbonate ions. Rising concentrations of atmospheric CO2 are acidifying the ocean and decreasing carbonate, and the team shows how this loss of carbonate affects the ability of phytoplankton to obtain enough of the nutrient iron for growth. Ocean acidification is poised to decrease the concentration of sea surface carbonate ions 50 percent by the end of this century.

The study, "Carbonate-sensitive phytotransferrin controls high-affinity iron uptake in diatoms," was funded by the National Science Foundation, the Gordon and Betty Moore Foundation, and the U.S. Department of Energy. It reveals an unexpected twist to the theory of how iron controls the growth of phytoplankton. By showing how the loss of seawater carbonate hampers the ability of phytoplankton to grab onto iron, the authors show a direct connection between the effects of ocean acidification and the health of phytoplankton at the base of the marine food chain.

"Ultimately our study reveals the possibility of a 'feedback mechanism' operating in parts of the ocean where iron already constrains the growth of phytoplankton," said Jeff McQuaid, lead author of the study who made the discoveries as a PhD student at Scripps Oceanography. "In these regions, high concentrations of atmospheric CO2 could decrease phytoplankton growth, restricting the ability of the ocean to absorb CO2 and thus leading to ever higher concentrations of CO2 accumulating in the atmosphere."

"Studies investigating the effects of high CO2 on phytoplankton growth have shown mixed results to date. In some cases, certain phytoplankton seem to benefit from high CO2," added Andrew E. Allen, a biologist with a joint appointment at Scripps and JCVI who is senior author and initiator of the study. "Most of these studies, however, have been conducted under high-iron conditions. Our study uncovers a widespread cellular mechanism that suggests high CO2 might be particularly problematic for phytoplankton growth in low-iron regions of the ocean."

Lead author Jeff McQuaid watches an array of pumps designed to test the effects of high CO2 on Ross Sea phytoplankton in Antarctica. Several recent studies have noted that high CO2 has a negative effect on phytoplankton growing in low iron environments like the Southern Ocean [Credit: A.E. Allen]

One consequence of acidification is a nearly one-for-one reduction in the concentration of carbonate ions for every molecule of CO2 that dissolves in the ocean. The concentration of atmospheric CO2 is predicted to double by the end of this century; thus, the concentration of carbonate ions at the surface of the ocean will nearly halve by the year 2100. While the negative influence of acidification on corals and shellfish is known, this is the first study to reveal a mechanism that affects life which forms the base of most marine food webs.

This study revises a key concept in oceanography that the growth of phytoplankton in vast areas of the ocean is regulated by the concentration of iron. In ocean regions that are high in dissolved nutrients like nitrogen and phosphorous, iron limitation results in low numbers of phytoplankton relative to amounts of available nutrients. Addition of iron to these areas causes phytoplankton, particularly diatoms, to grow. In the largest of these regions, the Southern Ocean, concentrations of available iron are below one trillionth of a gram per liter, approaching the limit supporting life.

Marine scientists have spent decades investigating how phytoplankton are able to grab such low concentrations of iron from seawater and internalize it.

"Understanding the mechanism of iron uptake is critical to develop meaningful predictions on how phytoplankton may respond to future ocean conditions, but this understanding has been elusive," said Adam Kustka, a trace metal physiologist and project collaborator from Rutgers University.

Clues began to emerge in 2008, when Allen discovered several iron-responsive genes in diatoms that had no known function. That same year, McQuaid was traveling around East Antarctica assisting in a survey of plankton in the Southern Ocean. DNA analysis of those samples revealed that one of Allen's iron genes was not only present in every sample of seawater, but every major phytoplankton group in the Southern Ocean seemed to have a copy.

"This gene, called ISIP2A, was one of the most abundantly transcribed genes in low-iron Southern Ocean, suggesting it had a really important role in the environment," said Allen.

Andrew Allen prepares a sample of phytoplankton filtered from the Ross Sea. In several of the Antarctic marine samples,  phytotransferrin was among the most abundant proteins detected [Credit: E. Bertrand]

Earlier studies suggested a transferrin-like protein, called phytotransferrin, was at work in the marine environment, but ISIP2A looked nothing like transferrin. It took the development of an entirely new discipline, synthetic biology, to help prove the team's hypothesis that ISIP2A was a type of transferrin. Synthetic biology is the fusion of biology and engineering, and in collaboration with scientists with the Venter Institute, the team developed methods to insert synthetic DNA into a marine diatom. The scientists deleted ISIP2A and replaced it with a synthetic gene for human transferrin, demonstrating that ISIP2A was a type of transferrin.

The team then initiated a study to investigate the evolutionary relationships of transferrin and phytotransferrin. To their surprise, the proteins were functional analogs whose ancient origins extend to the pre-Cambrian period of Earth history, predating the appearance of modern plants and animals.

"The appearance of phytotransferrin some 700 million years ago is consistent with a time in Earth's history marked by massive changes in ocean chemistry, and this ancient evolutionary history helps explain why no one has connected ISIP2A and transferrin," said Miroslav Oborník, a molecular evolutionary biologist from the University of South Bohemia and co-author on the paper.

In transferrin, iron and carbonate bind simultaneously, and neither can bind in the absence of the other. Such synergistic binding is unique among biological interactions. The research team hypothesized that diatom phytotransferrin uses a similar mechanism and that, as a result, reductions in carbonate ion could lead to reduced phytoplankton growth rates.

Using a number of biochemical methods, the researchers were able to independently manipulate pH along with the concentrations of iron and carbonate ion. As they pumped in increasing concentrations of CO2, the team showed that the ability of their diatom to grab onto iron decreased proportionally with the concentration of carbonate ions.

"Since carbonate and iron have to bind simultaneously, as carbonate concentrations drop, phytotransferrin is able to 'see' less iron," said McQuaid. "The total amount of iron isn't changing - rather the ability to grab onto it changes, and this ultimately influences the growth rate."

Source: University of California - San Diego [March 14, 2018]

Up to half of plant and animal species in the world's most naturally rich areas, such as the Amazon and the Galapagos, could face local extinction by the turn of the century due to climate change if carbon emissions continue to rise unchecked.

East Africa elephants [Credit: WWF]

Even if the Paris Climate Agreement 2°C target is met, these places could lose 25% of their species according to a landmark new study by the University of East Anglia (UK), the James Cook University (Australia), and WWF.

Published today in the journal Climatic Change and just ahead of Earth Hour, the world's largest environmental event, researchers examined the impact of climate change on nearly 80,000 plant and animal species in 35 of the world's most diverse and naturally wildlife-rich areas.

It explores a number of different climate change futures - from a no-emissions-cuts case in which global mean temperatures rise by 4.5°C , to a 2°C rise, the upper limit for temperature in the Paris Agreement . Each area was chosen for its uniqueness and the variety of plants and animals found there.

The report finds that the Miombo Woodlands, home to African wild dogs, south-west Australia and the Amazon-Guianas are projected to be some the most affected areas. If there was a 4.5°C global mean temperature rise, the climates in these areas are projected to become unsuitable for many the plants and animals that currently live there meaning:

• - Up to 90% of amphibians, 86% of birds and 80% of mammals could potentially become locally extinct in the Miombo Woodlands, Southern Africa
• - The Amazon could lose 69% of its plant species
• - In south-west Australia 89% of amphibians could become locally extinct
• - 60% of all species are at risk of localised extinction in Madagascar
• - The Fynbos in the Western Cape Region of South Africa, which is experiencing a drought that has led to water shortages in Cape Town, could face localised extinctions of a third of its species, many of which are unique to that region.
• 
  

Verreaux's sifaka in Madagascar [Credit: WWF]

As well as this, increased average temperatures and more erratic rainfall could become be the "new normal" according to the report - with significantly less rainfall in the Mediterranean, Madagascar and the Cerrado-Pantanal in Argentina. Potential effects include;

• - Pressure on the water supplies of African elephants - who need to drink 150-300 litres of water a day
• - 96% of the breeding grounds of Sundarbans tigers could become submerged by sea-level rise
• - Comparatively fewer male marine turtles due to temperature-induced sex assignment of eggs.

If species can move freely to new locations then the risk of local extinction decreases from around 25% to 20% with a 2°C global mean temperature rise. If species cannot they may not be able to survive. Most plants, amphibians and reptiles, such as orchids, frogs and lizards cannot move quickly enough keep up with these climatic changes.

Lead researcher Prof Rachel Warren from the Tyndall Centre for Climate Change Research at UEA said: "Our research quantifies the benefits of limiting global warming to 2°C for species in 35 of the world's most wildlife-rich areas. We studied 80,000 species of plants, mammals, birds, reptiles and amphibians and found that 50% of species could be lost from these areas without climate policy. However, if global warming is limited to 2°C above pre-industrial levels, this could be reduced to 25%. Limiting warming to within 1.5°C was not explored, but would be expected to protect even more wildlife."

Overall the research shows that the best way to protect against species loss is to keep global temperature rise as low as possible.

The Paris Agreement pledges to reduce the expected level of global warming from 4.5°C to around 3°C, which reduces the impacts, but we see even greater improvements at 2°C; and it is likely that limiting temperature rise to 1.5°C would protect more wildlife.

A giant panda from the Yangtze River area [Credit: WWF]

This is why on 24 March millions of people across the world will come together for Earth Hour, to show their commitment to reducing global emissions and protecting people and wildlife from the impacts of climate change. The event also sends a clear message to business and government that there is a global will to change this trajectory.

Tanya Steele, CEO of WWF commented: "Within our children's lifetime, places like the Amazon and Galapagos Islands could become unrecognisable, with half the species that live there wiped out by human-caused climate change. Around the world, beautiful iconic animals like Amur tigers or Javan rhinos are at risk of disappearing, as well as tens of thousands plants and smaller creatures that are the foundation of all life on earth. That is why this Earth Hour we are asking everyone to make a promise for the planet and make the everyday changes to protect our planet."

The models used in this research come from the Wallace Initiative, a near decade long partnership between the Tyndall Centre at UEA, eResearch at James Cook University, the Global Biodiversity Information Facility and WWF.

Dr Jeff Price, coordinator of the Wallace Initiative and also from UEA, said: "This research provides a view on the differing spatial impacts of climate change on biodiversity. It shows the benefits of combining citizen science with the research and resources of highly-ranked universities to assist an NGO with their conservation activities."

Source: University of East Anglia [March 13, 2018]

Poaching and habitat loss have reduced forest elephant populations in Central Africa by 63 percent since 2001. This widespread killing poses dire consequences not only for the species itself but also for the region's forests, a new Duke University study finds.

Populations of forests elephants, which play key roles in maintaining forest habitat, have declined 63 percent in Central Africa since 2001. Without intervention to prevent further losses, 96 percent of the region's forests could undergo major change [Credit: John Poulsen, Duke University]

"Without intervention to stop poaching, as much as 96 percent of Central Africa's forests will undergo major changes in tree-species composition and structure as local populations of elephants are extirpated and surviving populations are crowded into ever-smaller forest remnants," said John Poulsen, assistant professor of tropical ecology at Duke's Nicholas School of the Environment.

These changes will occur because elephants are ecological engineers that help create and maintain forest habitat by dispersing seeds, recycling and spreading nutrients, and clearing understories, Poulsen explained.

"Because they are very large animals, they can eat fruits and disperse seeds too big for other animals to digest. And because they are highly mobile, they help disperse these seeds far and wide through their dung," he said.

In the elephants' absence, scores of tree species may be left without a means of long-distance seed dispersal, which is essential for forest structure and colonization. Trees whose seeds are dispersed by smaller animals could fill the void, dramatically altering forest composition.

Fewer elephants will also mean a more limited distribution of the nutrients contained in their dung.

"Many of Central Africa's forests are nitrogen limited. Elephants help compensate by moving nutrients, especially nitrogen, across the landscape as they defecate. If populations continue to shrink, this nitrogen will be concentrated in smaller and smaller areas, limiting future tree growth elsewhere," Poulsen said.

Understory density will also be affected.

"Elephants have a large effect on forests by eating or trampling slow-growing plants and opening the understory, allowing more light in and reducing competition for water and nutrients," Poulsen said. "These changes alter the recruitment regimes of tree species -- favoring some and not others."

He and his colleagues published their peer-reviewed study in the journal Conservation Biology.

To conduct their analysis, they reviewed 158 previous studies on forest elephant behaviors and their cascading ecological impacts. By cross-referencing these impacts with data on local elephant populations, forest tree-species composition and structure, nutrient availability, and understory growth in existing Central African forests -- both protected and unprotected ones alike -- Poulsen and his team determined that up to 96 percent of all forests in the region were susceptible to dramatic changes if elephant populations shrank or disappeared.

"Stopping poaching is an urgently needed first step to mitigating these effects," he said, "but it will not be easy. Long-term conservation will require land-use planning that incorporates elephant habitat into forested landscapes that are being rapidly transformed by industrial agriculture and logging."

Source: Duke University [March 12, 2018]

About 2 to 3 million years ago, a group of spiders let out long silk threads into the wind and set sail, so to speak, across the Pacific Ocean to Hawaii. These spiders were parasites of other spiders, invading their webs, snipping threads to steal insects that had been caught. But there weren't many webs to rob on Hawaii when they arrived. So they expanded their repertoire, looking for other ways to survive by trapping and eating other spiders. A new species evolved from those first spiders, after finding a way to live on rocks. And then another species evolved to live under leaves. And then another. And then 11 more species.

Gold Molokai spider [Credit: George Roderick]

Charles Darwin first noted this phenomenon, called adaptive radiation, in the beaks of finches of the Galapagos Islands. His study of the finches' diversity led to his theory of evolution by natural selection. Yet today, much remains unknown about how adaptive radiation, and thus evolution, actually work. Hawaii is even more of a hotbed for biological diversification than the Galapagos due to its isolation.

In Hawaiian Ariamnes stick spiders, adaptive radiation has resulted in 14 species now living across Hawaii. They share a generally similar body type, but each is a separate species with distinct physical traits. Remarkably, stick spiders with similar traits - yellow and red coloring, for example - live on different Hawaiian islands but aren't each other's closest relatives; they are a rare instance where a physical form has evolved separately on each island, according to a new study by scientists at the University of California, Berkeley. The study shows that evolution has led to a predictable and independently evolved set of similar forms in spiders on each island.

"This very predictable repeated evolution of the same forms is fascinating because it sheds light on how evolution actually happens," said Rosemary Gillespie, professor and Schlinger Chair in Systematic Entomology at UC Berkeley and lead author of the paper. "Such outstanding predictability is rare and is only found in a few other organisms that similarly move around the vegetation."

Ariamnes corniger, a stick spider from East Maui, Hawaiian Archipelago. This white matte ecomorph is cryptic against lichen [Credit: George Roderick]

The study of Ariamnes stick spiders will be published in the journal Current Biology. It was funded by the National Science Foundation and the William M. and Esther G. Schlinger Foundation.

"This study provides insights into a fundamental question about the origins of biodiversity, but also presents a remarkable story that can call attention to the need for conserving nature in all of its forms," said study co-author George Roderick, professor and chair of the Department of Environmental Science Policy and Management at Berkeley.

Hawaii is a chain of islands that formed chronologically, so the scientists were able to study the spiders' adaptive radiations over time as they moved from old to new islands. The oldest island, Kauai, was formed 5 million years ago, followed by Oahu, Molokai, Lanai, Maui and finally the big island of Hawaii, the youngest at less than 1 million years old.

The study found that stick spiders have evolved and differentiated from a single species on the same island. So, spider types on any one island were generally more closely related to very different looking spiders on the same island than to spiders that looked the same on other islands. For instance, a white spider on Oahu is a closer relative to the brown spider on the same island than it is to a white spider on Maui.

An undescribed species of Ariamnes from Kauai, Hawaiian Archipelago. It is an example of the dark ecomorph [Credit: George Roderick]

"You can find these spiders in pretty much every habitat on each island," Gillespie said. "This really detailed and finely tuned repetition of evolution of the same form is really quite uncommon."

The spiders can be grouped into three distinct ecological types, called ecomorphs: A brown one that lives in rocks; a gold one that lives in under leaves, and a white one that's a matte color and lives on lichen.

The analysis of stick spiders mirrors Gillespie's previous discovery in Hawaiian Tetragnatha spiders, another group that shows remarkable adaptive radiation. This group of spiny-legged spiders does not spin a web and has repeatedly evolved similar ecomorphs since its ancestor arrived in Hawaii. That study was featured on the cover of the journal Science in 2004.

The varied habitat types on the Hawaiian Islands, cold and wet areas closely juxtaposed with hot and dry, have provided a rich tapestry of species diversity. The flip side of such extraordinary diversity that evolved in isolation is its vulnerability to change and to invasive species that are now flooding in as a result of human traffic, Gillespie said.

"We need to be able to figure out this diversity and document it and describe what's so special about it, so that people know about it," Gillespie said. "It's being lost and it's a desperate situation."

Source: University of California - Berkeley [March 08, 2018]

For nearly two decades, scientists have noted dramatic changes in arctic tundra habitat. Ankle-high grasses and sedges have given way to a sea of woody shrubs growing to waist- or neck-deep heights. This shrubification of the tundra challenges animals like caribou that are adapted to low-stature arctic vegetation.

Microscopic imaging reveals the pattern of annual rings in shrub stems, which the researchers used to determine that shrub growth is controlled by temperatures in June, the first month of the brief arctic growing season [Credit: Daniel Ackerman]

Pinpointing a cause has been difficult. However, new UMN research published in Environmental Research Letters found that regardless of soil fertility or rainfall amounts, the single variable that was by far the strongest determinant of how much a shrub grew in a given year was the temperature in June. A warmer June means faster shrub growth.

"It was a surprising result," said Daniel Ackerman, a Ph.D. candidate in the Department of Ecology, Evolution and Behavior in the College of Biological Sciences who led the UMN research team that traveled to the tundra in northern Alaska to investigate why the habitat was changing. "Other variables, including temperatures during the rest of the growing season in July and August, barely had an impact on shrub growth."

University of Minnesota researcher Daniel Ackerman wades through neck-deep shrubs in northern Alaska to collect samples [Credit: Meera Subramanian]

Like trees at lower latitudes, shrubs in the tundra form a concentric ring around their stem each growing season. Ackerman's team used these annual rings to their advantage, collecting hundreds of shrub stems across a range of soil conditions. They measured the size of each annual ring in their samples--no easy task given that these shrubs can contain more than 50 rings in a stem with the diameter of a pencil.

After painstakingly measuring 20,000 individual shrub rings through a microscope, the team created records of historic shrub growth from across northern Alaska. Next, before coming to their findings, the team compared these growth records to climate observations, examining factors like precipitation, temperature, and solar radiation.

"Our new understanding of the link between June temperature and shrub growth means that we can expect shrubification to continue throughout northern Alaska," said Ackerman. "With this study and others like it, we're beginning to understand the causes of shrubification. However, we still have a ways to go in predicting its effects. It seems like larger shrubs will benefit some animals, like moose and ptarmigan, while other animals, like caribou, could be harmed."

Source: University of Minnesota [March 06, 2018]

In a study spanning twelve years, researchers from Kyoto University, and with Ryukoku University have developed a method to calculate the fluctuating stability of a natural ecological community in Maizuru Bay.

Kyoto researchers spend a decade tracking changes in fish communities [Credit: Kyoto University/Reiji Masuda]

Their findings, published in Nature, provide insight into and new methodologies for ecological and population research.

How biological communities are maintained is a big question in ecology. While current studies suggest community stability can be influenced by species diversity and interactions, these ideas have almost never been tested in natural ecosystems.

"Previous research focused on issues such as the birth-death process, like when a predator eats prey, and inside a somewhat controlled environment," explains lead author Masayuki Ushio. "Even then, it is challenging to measure the rapidly changing interactions of multiple species in nature."

A key reason for this is that natural ecosystems do not typically exhibit equilibrium dynamics, and so the most viable way to measure changes is to keep constant records of organisms in a particular location.

Fortunately, Reiji Masuda of the Field Science Education and Research Center has been doing just that in Maizuru Bay. For twelve years, he has been diving into the waters every two weeks, recording the populations of all the fish and jellyfish he encountered.

"I initially started these observations in 2002 to see what organisms lived in the area and how they change over time," Masuda describes. "When I showed my work to Masayuki Ushio and Michio Kondoh at Ryukoku University, they suggested we work together and build a model to chart the interactions between the organisms."

The model was constructed by applying a time series analysis tool -- empirical dynamic modeling, or EDM -- to the Maizuru Bay data set. EDM is designed to analyze the fluctuating dynamics of a natural ecosystem, without setting any defined equations. This was then further developed to analyze the ecosystem's dynamic stability.

What they found was a complex web of interactions, where organisms have positive or negative effects on each other, and more importantly, showed that short-term changes in the network influences overall community dynamics.

"We could even see that things such as diversity, species interactions, and stability itself fluctuate throughout time," says Ushio. "This suggests that these properties are key to understanding the mechanisms underlying the functioning of natural ecosystems."

The team's methods can be readily applied to other fields, from neuroscience, microbiology, to economics.

"This is by far one of the most comprehensive looks at how much an ecosystem can change in the natural world," concludes team leader Michio Kondoh. "I was surprised to see that community stability, which is often assumed to be constant, is in fact changing over time. The robustness of ecological communities depends on timing and seasons."

Source: Kyoto University [March 02, 2018]

Rainforest loss is fuelling a tsunami of tropical species extinctions. However, not all is doom and gloom. A new study, conducted in the Brazilian Amazon, suggests that ecological cataclysms prompted by the fragmentation of the forest can be reverted by the regeneration of secondary forests, offering a beacon of hope for tropical forest biodiversity across the world.

Credit: Mark Moffett/ Minden Pictures/National Geographic Stock

The international team of researchers found that species strongly associated with primary forest were heavily depleted after 15 years of man-made disruption including the burning and clearing of forest stands,

However, 30 years down the line, and with the regeneration of secondary regrowth, many of the species that had abandoned the area had made a comeback.

"If you compare the time periods, it is apparent that taking a long-term view is paramount to uncovering the complexity of biodiversity in human-modified landscapes," said senior researcher Dr. Christoph Meyer, lecturer in global ecology and conservation at the University of Salford.

The study, published in Nature: Scientific Reports, measured the impacts of forest break-up of 50 species of bat (approx. 6,000 animals).

Bats comprise roughly one fifth of all mammal species and display wide variation in foraging behaviour and habitat use, making them an excellent model group for the research.

"The responses exhibited by bats offer important insights into the responses of other taxonomic groups." says Ricardo Rocha, lead author of the study from the University of Lisbon.

"The recovery that we have documented mirrors the patterns observed for beetle and bird communities within the Amazon.

"These parallel trends reinforce the idea that the benefits of forest regeneration are widespread, and suggest that habitat restoration can ameliorate some of the harm inflicted by humans on tropical wildlife", he adds.

The results of the current study contrast with the catastrophic faunal declines observed during a similar time window in rodent communities in the 'forest islands' of the Chiew Larn reservoir in Thailand.

"The recovery observed at the Amazon was mostly due to the recolonization of previously deforested areas and forest fragments by old-growth specialist bats. This recolonization is likely attributable to an increased diversity and abundance of food resources in areas now occupied by secondary forest, fulfilling the energetic requirements of a larger set of species", explains Rocha.

However, the short-term nature of most studies has substantially impaired the capacity of researchers to properly capture the intricate time-related complexities associated with the effects of forest fragmentation on wildlife.

Source: University of Salford [February 28, 2018]

Fields, streets and cities, but also forests planted in rank and file, and dead straight rivers: humans shape nature to better suit their purposes, and not only since the onset of industrialization. Such influences are well documented in the Amazonian rainforest. On the other hand, the influence of humans was debated in Central Africa where major interventions seem to have occurred there 2,600 years ago: Potsdam geoscientist Yannick Garcin and his team have published a report on their findings in the Proceedings of the National Academy of Sciences. The research team examined lake sediments in southern Cameroon to solve the riddle of the "rainforest crisis." They found that the drastic transformation of the rainforest ecosystem at this time wasn't a result of climatic change, it was humankind.

Farming activities in North-West Region of Cameroon [Credit: Better World Cameroon]

More than 20 years ago, the analysis of lake sediments from Lake Barombi in southern Cameroon showed that older sediment layers mainly contained tree pollen reflecting a dense forested environment. In contrast, the newer sediments contained a significant proportion of savannah pollen: the dense primitive forest quickly transformed into savannahs around 2,600 years ago, followed by an equally abrupt recovery of the forest approximately 600 years later. For a long time, the most probable cause of this sudden change, dubbed the "rainforest crisis," was thought to be climate change brought about by a decrease in precipitation amount and increase in precipitation seasonality. Despite some controversy, the origin of the rainforest crisis was thought to be settled.

High volumes of precipitation in the region (over 3,000 mm annually) have ensured that the lake has not dried out over the millenia. This heavy rainfall has created large volumes of sediment, which are then washed into the lake. These circumstances make it possible to perform sediment analyses with the utmost precision [Credit: B. Brademann/GFZ]

Yet Garcin, a postdoctoral researcher at the University of Potsdam, and his international team of scientists from UP, CEREGE, IRD, ENS Lyon, GFZ, MARUM, AMU, AWI, and from Cameroon suspected that other causes could have led to the ecosystem's transformation. By reconstructing both vegetation and climate change independently -- through stable isotope analysis of plant waxes, molecular fossils preserved in the sediment -- the team confirmed that there was a large change in vegetation during the rainforest crisis, but indicated that this was not accompanied by a change in precipitation.

"The rainforest crisis is proven, but it cannot be explained by a climate change," says Garcin. "In fact, in over 460 archaeological finds in the region, we have found indications that humans triggered these changes in the ecosystem." Archaeological remains older than 3,000 years are rare in Central Africa. Around 2,600 years ago, coincident with the rainforest crisis, the number of sites increased significantly, suggesting a rapid human population growth -- probably related to the expansion of the Bantu-speaking peoples in Central Africa. This period also saw the emergence of pearl millet cultivation, oil palm use, and iron metallurgy in the region.

This floating platform can be completely taken apart and transported overseas. The platform enabled the collection of sediment samples in the approximately 100-meter-deep Lake Barombi, which were then analyzed in the laboratory [Credit: Y. Garcin/University of Potsdam]

"The combination of regional archaeological data and our results from the sediments of Lake Barombi shows convincingly that humans strongly impacted the tropical forests of Central Africa thousands of years ago, and left detectable anthropogenic footprints in geological archives," says Dirk Sachse at the Helmholtz Center Potsdam -- Research Center for Geosciences (GFZ). Sachse was one of the major contributors to the development of the method for analyzing plant wax molecular fossils (termed biomarkers).

"We are therefore convinced that it was not climate change that caused the rainforest crisis 2,600 years ago, but it was the growing populations that settled in the region and needed to clear the forest for exploiting arable land," says Garcin. "We are currently observing a similar process underway in many parts of Africa, South America, and Asia." But the work of Garcin and his team also shows that nature has powerful regenerative abilities. When anthropogenic pressure decreased 2,000 years ago forest ecosystems reconstituted, but not necessarily as before: as in the Amazonian rainforest, field studies show that the presence of certain species is very often related to past human activity.

Source: GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre [February 26, 2018]

For the first time, researchers have seen life rebounding in the world's driest desert, demonstrating that it could also be lurking in the soils of Mars.

Hyperarid core of the Atacama Desert [Credit: Dirk Schulze-Makuch]

Led by Washington State University planetary scientist Dirk Schulze-Makuch, an international team studied the driest corner of South America's Atacama Desert, where decades pass without any rain.

Scientists have long wondered whether microbes in the soil of this hyperarid environment, the most similar place on Earth to the Martian surface, are permanent residents or merely dying vestiges of life, blown in by the weather.

In a new study published in the Proceedings of the National Academy of Sciences, Schulze-Makuch and his collaborators reveal that even the hyper-arid Atacama Desert can provide a habitable environment for microorganisms.

The researchers found that specialized bacteria are able to live in the soil, going dormant for decades, without water and then reactivating and reproducing when it rains.

"It has always fascinated me to go to the places where people don't think anything could possibly survive and discover that life has somehow found a way to make it work," Schulze-Makuch said. "Jurassic Park references aside, our research tell us that if life can persist in Earth's driest environment there is a good chance it could be hanging in there on Mars in a similar fashion."

The dry limit of life

When Schulze-Makuch and his collaborators went to the Atacama for the first time in 2015 to study how organisms survive in the soil of Earth's driest environment, the craziest of things happened. It rained.

After the extremely rare shower, the researchers detected an explosion of biological activity in the Atacama soil.

These are the surfaces of Mars and the Atacama Desert [Credit: NASA (left) / Alessandro Airo, TU Berlin (right)]

They used sterilized spoons and other delicate instrumentation to scoop soil samples from various depths and then performed genomic analyses to identify the different microbial communities that were reproducing in the samples. The researchers found several indigenous species of microbial life that had adapted to live in the harsh environment.

The researchers returned to the Atacama in 2016 and 2017 to follow up on their initial sampling and found that the same microbial communities in the soil were gradually reverting to a dormant state as the moisture went away.

"In the past researchers have found dying organisms near the surface and remnants of DNA but this is really the first time that anyone has been able to identify a persistent form of life living in the soil of the Atacama Desert," Schulze-Makuch said. "We believe these microbial communities can lay dormant for hundreds or even thousands of years in conditions very similar to what you would find on a planet like Mars and then come back to life when it rains."

Implications for life on Mars

While life in the driest regions of Earth is tough, the Martian surface is an even harsher environment.

It is akin to a drier and much colder version of the Atacama Desert. However it wasn't always this way.

Billions of years ago, Mars had small oceans and lakes where early lifeforms may have thrived. As the planet dried up and grew colder, these organisms could have evolved many of the adaptations lifeforms in the Atacama soil use to survive on Earth, Schulze-Makuch said.

"We know there is water frozen in the Martian soil and recent research strongly suggests nightly snowfalls and other increased moisture events near the surface," he said. "If life ever evolved on Mars, our research suggests it could have found a subsurface niche beneath today's severely hyper-arid surface."

Next Steps

On March 15, Schulze-Makuch is returning to the Atacama for two weeks to investigate how the Atacama's native inhabitants have adapted to survive. He said his research team also would like to look for lifeforms in the Don Juan Pond in Antarctica, a very shallow lake that is so salty it remains liquid even at temperatures as low as -58 degrees Fahrenheit.

"There are only a few places left on Earth to go looking for new lifeforms that survive in the kind of environments you would find on Mars," Schulze-Makuch said. "Our goal is to understand how they are able to do it so we will know what to look for on the Martian surface."

Author: Will Ferguson | Source: Washington State University [February 26, 2018]

A new theory of plant evolution suggests that the 400 million-year drive of flora across the globe may not have been propelled by the above-ground traits we can see easily, but by underground adaptations that allowed plants to become more efficient and independent.

Researchers from Princeton University and the Chinese Academy of Sciences have posed a theory of plant evolution based on root adaptations that allowed plants to become more efficient and independent. The cross sections above show that the roots of plants such as the subtropical oak species Lithocarpus chintungensis (largest cross section, center left) and the tropical species Parashorea chinensis (lower-right of largest cross section) retained their ancestral thickness and reliance on the symbiotic fungi (purple ring) that surround the root to help it obtain nutrients. As plant species spread from their nutrient-rich tropical origins, however, the root tips of plants such as the desert shrub species Tamarix ramosissima (left of largest cross section) evolved to be thinner so they could more efficiently explore soil for nutrients, and they have less dependence on symbiotic fungi [Credit: Zeqing Ma, Chinese Academy of Sciences]

As plant species spread north and south from their nutrient-rich tropical beginnings, the fine tips of their roots became narrower and more widespread to help them explore increasingly poor soil for vital nutrients, according to a study in the journal Nature led by researchers from Princeton University and the Chinese Academy of Sciences (CAS) in Beijing. In addition, as plants spread into unpredictable environments such as arid deserts they grew less dependent on the symbiotic fungi -- or mycorrhiza -- that colonize roots and help host plants obtain the essential plant nutrients nitrogen and phosphorous.

The findings reconsider how plants adapted to new environments as they evolved, said corresponding author Lars Hedin, the George M. Moffett Professor of Biology and chair and professor of ecology and evolutionary biology and the Princeton Environmental Institute. Scientists have in the past focused on above-ground characteristics, primarily leaf traits and the efficiency with which plants absorb sunlight for photosynthesis, he said.

Instead, Hedin said, he and his colleagues have found for the first time that root diameter and reliance on fungi -- or the lack thereof -- are the traits that most consistently characterize the plant community across entire biomes, which are large distinct communities of animals and plants such as a desert, temperate forest or savanna.

"These are the secret strategies that plants have used over time to take over the world," Hedin said. "Our goal was to unlock the understanding of those strategies, and our findings offer a new global theory for plant evolution. Hidden underground there has been a tremendous game of survival-of-the-fittest and we are fortunate to have the first-ever view of the science of that game.

"This work has major implications for conservation and our stewardship of the plant world," Hedin continued. "It provides some of the hidden, below-ground rules by which plants survive and spread. It's a global view of plant evolution at a time when global rules are essential for building climate models and understanding the biosphere."

Mingzhen Lu, first Princeton author and a graduate student in Hedin's research group, said that if root traits do in fact determine a plant's ability to withstand a particular environment, these findings could be valuable in conserving endangered species or projecting how plants might adapt to climate change.

"Our findings simplify how we can practically characterize a plant's strategy for obtaining nutrients," Lu said. "Knowing their underlying nutrient strategy will help us know how to preserve them, or know the conditions under which they could or could not survive."

Kurt Pregitzer, the Thomas Reveley Professor and dean of the College of Natural Resources at the University of Idaho, said this work could be especially useful in combating invasive species, which, in a highly mobile world, increasingly threaten biodiversity. Pregitzer is familiar with the research but had no role in it.

"Invasive species cause widespread displacement of native plants and tremendous economic impacts across the globe," Pregitzer said. "This study may open entirely new lines of scientific investigation that help us better understand how invasive-plant root systems help these exotic species outcompete native plants."

The researchers spent two years examining a database of root traits consisting of 369 species from seven biomes (above): desert, grassland, Mediterranean, boreal, temperate, subtropical and tropical. Woody biomes are identified as shades of tan-to-yellow and non-woody biomes are in shades of green. The researchers found that plants in tropical (light orange) and subtropical biomes (beige) exhibited the largest range of root-tip diameters, from less than 0.25 millimeters up to 1 millimeter. These plants rely on soil fungi to provide nutrients, a similar strategy to that of Earth's earliest land plants. Plants in biomes characterized by poor soil, cold winters and/or infrequent precipitation have a narrow root-diameter range ideal for that environment. The desert (light green) and grassland (green) species studied all had root diameters of less than 0.25 millimeters [Credit: Lars Hedin and Mingzhen Lu, Department of Ecology and Evolutionary Biology]

The Nature paper is unique for its scale and careful application of scientific methods, Pregitzer said. "This study is the first conducted across a wide range of terrestrial environments and it demonstrates that plant species have evolved root strategies that are conserved within corresponding families, genera and species," he said. "These root traits likely facilitate plant success in highly competitive natural ecosystems."

The researchers spent two years examining a uniquely large database of root traits consisting of 369 species from seven biomes: desert, grassland, Mediterranean, boreal, temperate, subtropical and tropical.

These data were compiled over the course of a decade in the lab of late co-corresponding author Dali Guo, a professor at CAS' Institute of Geographic Sciences and Natural Resources Research. First author Zeqing Ma is a research associate in Guo's lab and co-author Xiangliang Xu is a colleague of Guo's. The paper's co-authors also included root experts Richard Bardgett, professor of ecology at the University of Manchester in the UK; David Eissenstat, professor of woody plant physiology at Pennsylvania State University; and M. Luke McCormack, a research associate at the University of Minnesota.

The researchers found that plants in tropical and subtropical biomes exhibited the largest diameter range for the finest root tips that forage for nutrients, from less than 0.25 millimeters up to 1 millimeter. These thicker-rooted plants employ what the authors call a "conservative" strategy -- similar to that of Earth's earliest land plants -- that relies on the soil fungi prevalent in wet, warm tropical and subtropical soils to provide nutrients. The researchers refer to nutrient-rich soil in consistently sultry environs as "predictable."

Meanwhile, fine-root diameters in "unpredictable" biomes characterized by poor soil, cold winters and/or infrequent precipitation fall within a narrower range ideal for that environment. For instance, the desert and grassland species studied all had root diameters of less than 0.25 millimeters. Root tips in these biomes evolved to be thinner so they could more efficiently explore soil for every unit of carbon the plant expends, and they have less dependence on symbiotic fungi.

The extensive data the researchers used allowed them to explore the evolution of plant roots to an extent never before possible, Lu said. "Below-ground plant ecology has been understudied, limited by a paucity of data," he said. "Because of that, the governing rule of what's going on below ground has been very poorly known."

"Thus far," Hedin added, "everybody has quite naturally tried to understand how plants are organized by looking at above-ground traits. But our findings do not follow the above-ground theories -- that was a surprise."

The study reveals that root and leaf evolution have followed different paths, Pregitzer said. Plant ecologists have known that the form and function of leaves are essential to a plant species' success, but "we did not understand if this was true across the tremendous diversity of plant root systems," he said.

"Interestingly, little was known about how plant roots have evolved to facilitate success in their native habitats," Pregitzer said. "Now we know that leaves and roots have responded to different evolutionary selective pressures, and we can start building a better understanding of how root form and function drive plant success within the tremendous biological diversity we see on Earth."

The findings align with ideas explored at Princeton that suggest that plants -- rather than being passive features of their environment -- have actively adapted to and shaped their environments, Hedin said. He was senior author of a 2015 paper in Nature Plants that suggested that ecosystems take their various forms because plants behave in ways that not only benefit themselves but also determine the productivity and composition of their habitats.

"Over evolutionary time, it's as if plants have actively explored the best strategies to safeguard their own survival," Hedin said. He and Lu brought this perspective to the database put together by their colleagues at CAS.

"We understood from a plant perspective how to bring evolutionary questions to their unique global dataset," Hedin said. "It was this great collaboration where we combined new ideas with years of painstaking fieldwork to produce this great result. It couldn't have happened without both sides."

Source: Princeton University [February 21, 2018]

The ocean around the Galápagos Islands has been warming since the 1970s, according to a new analysis of the natural temperature archives stored in coral reefs.

Diane Thompson (left), Roberto Pépolas (center) and Alexander Tudhope (right) use a hydraulic drill to take a core from a Porites lobata coral head near Wolf Island in the Galápagos [Credit: Jenifer Suarez, Cole lab]

The finding surprised the University of Arizona-led research team, because the sparse instrumental records for sea surface temperature for that part of the eastern tropical Pacific Ocean did not show warming.

"People didn't know that the Galápagos or eastern Pacific was warming. People theorized or suggested it was cooling," said lead author Gloria Jimenez, a UA doctoral candidate in geosciences.

Scientists thought strong upwelling of colder deep waters spared the region from the warming seen in other parts of the Pacific, she said.

"My colleagues and I show that the ocean around the northern Galápagos Islands is warming and has been since the 1970s," Jimenez said. The research is part of her doctoral work.

Jimenez studied cores taken from coral heads in the uninhabited northern part of Galápagos National Park. The cores represented the years 1940 to 2010. Corals lay down seasonal growth layers that serve as a natural archive of ocean temperatures.

Her analysis revealed that from 1979 to 2010, regional ocean temperatures increased almost 0.4 degrees F (0.2 degrees C) per decade -- about 1.1 degrees F (0.6 degrees C) overall.

The very strong El Niño of 1982-83 temporarily warmed the surrounding ocean so much that most of the corals in the southern part of the Galápagos died, said co-author Julia Cole, who collected the coral cores while she was a faculty member at the UA.

She is concerned about ocean warming around the northern Galápagos and parts of the eastern tropical Pacific.

"Warming in this area is particularly disturbing, because it's the only place that reefs have persisted in the Galápagos. This suggests those reefs are more vulnerable than we thought," said Cole, who is now a professor of earth and environmental sciences at the University of Michigan.

Cores collected in 2010 from a Porites lobate coral near Wolf Island in Galapagos Islands. The core, now broken into three pieces, is 3.5 inches (8.9 cm) in diameter [Credit: Julia Cole © 2010]

The research paper, "Northern Galápagos corals reveal twentieth century warming in the eastern tropical Pacific," by Jimenez, Cole and their co-authors, Diane M. Thompson of Boston University in Massachusetts and Alexander W. Tudhope of the University of Edinburgh in the UK, is published in Geophysical Research Letters.

The National Science Foundation, the UK Natural Environment Research Council and the Philanthropic Education Organization Fellowship funded the research.

For 30 years, Cole, a paleoclimatologist, has been studying climate change and the El Niño/ La Niña climate cycle.

In 1989 she went to the Galápagos hoping to use the natural climate archives stored in corals to develop a long-term record of El Niño, but found that none of the large, old corals others reported had survived the intense warming of the 1982-83 El Niño.

"We went from site to site -- and they were all gone," Cole said. "One of my co-workers said, 'There used to be corals here, and now all I see is sand.'"

Years later, she heard large corals were still alive near Wolf Island in the remote northern part of the Galápagos archipelago, so in 2010 she followed up on the tip with a team that included co-authors Tudhope and Thompson, then a UA graduate student.

The team members dove to the reef and took several cores from large, blobby dome-shaped Porites lobata corals using an underwater hydraulic drill powered by vegetable oil. The three-and-a-half-inch (8.9 cm) diameter cores ranged from two to three feet long and had annual bands 0.4 to 0.8 inches (1-2 cm) wide. Each core showed damage from when the coral stopped growing during the 1982-83 El Niño and then started growing again.

Jimenez used chemical analysis to tease temperature information out of two of those coral cores.

After removing two cores from this Porites lobata coral colony near Wolf Island in the Galápagos, the University of Arizona-led team of researchers plugged the drill holes. The cement plugs help the coral grow over the holes and keep out animals out of the holes [Credit: Diane Thompson © 2010]

Coral skeletons are made mostly of calcium carbonate. However, corals sometimes substitute the element strontium for the calcium. Corals substitute more strontium when the water is cold and less when the water is warm, so the strontium/calcium ratio of a bit of skeleton can reveal what the water temperature was when that piece of skeleton formed.

Jimenez used a little drill bit to take a tiny sample every millimeter for the length of each core. She took 10 to 20 samples from each annual band of each core and analyzed the samples for the strontium/calcium ratio using atomic emission spectrometry.

She then used that information to create a continuous record of the region's ocean temperature from 1940 to 2010.

Because the El Niño/ La Niña climate cycle generates large fluctuations in ocean temperatures around the Galápagos and in the eastern tropical Pacific, long-term changes can be hard to spot.

Jimenez wanted to determine whether the region's ocean temperature changed significantly from 1940 to 2010. Therefore she analyzed her Galápagos coral temperature chronologies alongside published coral temperature chronologies from islands farther north and west and instrumental sea surface temperature records from the southern Galápagos town of Puerto Ayora and the Peruvian coastal town of Puerto Chicama.

Jimenez said her research convinces her that the ocean around the Galápagos and much of the eastern tropical Pacific is warming. She's concerned about the effect of warming seas.

"The Galápagos National Park has been designated a World Heritage Site because it's a special and unique place," Jimenez said. "Losing the corals would be an enormous blow to the underwater biodiversity."

Jimenez's next project involves analyzing an eight-foot-long Galápagos coral core she collected in 2015 that goes back to about 1850.

Author: Mari N. Jensen | Source: University of Arizona [February 21, 2018]

On the Himalayan-enveloped Tibetan Plateau and the Altiplano plateau of South America - the world's two highest tabletops - a select few bird species survive on 35 to 40 percent less oxygen than at sea level.

A rendering of avian hemoglobin, the blood protein that captures and delivers oxygen throughout the body [Credit: PNAS]

All extreme-altitude birds have evolved especially efficient systems for delivering that precious oxygen to their tissues. But a new study led by the University of Nebraska-Lincoln and Chinese Academy of Sciences has found that these birds often evolved different blueprints for assembling the proteins - hemoglobins - that actually capture oxygen.

Published in the Proceedings of the National Academy of Sciences, the study found that many species from the two plateaus underwent different mutations to produce the same result: hemoglobins more adept at snaring oxygen from the lungs before sharing it with the other organs that depend on it.

Those mutational differences often emerged even among closely related species residing on the same plateau, the study reported.

"You could imagine, just because of the different ancestral starting points, that the Tibetan birds maybe all went one (mutational) route, and the Andean birds typically did things a different way," said co-author Jay Storz, Susan J. Rosowski Professor of biological sciences at Nebraska. "But that's not what we saw. Across the board, there weren't really any region-specific patterns.

"In both cases, it seems like there were many different ways of evolving a similar alteration of protein function."

Jay Storz stands on the Tibetan Plateau, more than 15,000 feet above sea level. Storz and his colleagues have shown that many high-altitude bird species underwent different mutations to develop the same adaptation: hemoglobin better at capturing and distributing scarce oxygen [Credit: University of Nebraska-Lincoln]

Like all proteins, hemoglobin consists of intricately folded chains of amino acids. The interactions among those amino acids dictate the structure of a protein, which in turn determines its properties - how readily it binds with and releases oxygen, for instance. But a mutation can effectively swap out an amino acid for a chemically distinct version at the same site in the protein, potentially modifying its behavior in the process.

After comparing the ancestral vs. modern hemoglobin proteins of nine species that inhabit the Tibetan Plateau, the team did identify two cases in which distantly related species underwent identical, functionally important mutations. Yet in the other instances, species evolved different ways to build a better hemoglobin.

The latest findings reinforce a 2016 Storz-led study published in the journal Science, which was the first to establish that vertebrate species can follow different molecular-level paths to reach the same adaptation. That study, which investigated birds only from the Andes, inspired the team to follow up with its comparison of Andean and Himalayan species.

"Birds that have adapted to high-altitude conditions from all these different mountain ranges have repeatedly evolved hemoglobin with elevated oxygen affinities," Storz said. "At that (functional) level, everything is highly repeatable, and there's a very striking pattern of convergent evolution. But in terms of the actual molecular underpinnings, there's far less predictability, and it's clear that there are many possible changes that can produce the same functional outcome."

Source: University of Nebraska-Lincoln [February 20, 2018]

Natural ecosystems play a crucial role in helping combat climate change, air pollution and soil erosion. A new study by a team of researchers from the Joint Research Centre, the European Commission's science and knowledge service, sheds light on another, less well-known aspect of how these ecosystems, and forests in particular, can protect our planet against global warming.

Changes to the way land is used is having a knock-on effect on temperatures [Credit: European Commission Joint Research Centre]

The research team used satellite data to analyse changes in global vegetation cover from 2000 to 2015 and link these to changes in the surface energy balance. Modifying the vegetation cover alters the surface properties - such as the amount of heat dissipated by water evaporation and the level of radiation reflected back into space - which has a knock-on effect on local surface temperature. Their analysis reveals how recent land cover changes have ultimately made the planet warmer.

"We knew that forests have a role in regulating surface temperatures and that deforestation affects the climate, but this is the first global data-driven assessment that has enabled us to systematically map the biophysical mechanisms behind these processes", explains Gregory Duveiller, lead author of the study.

The study also looked beyond deforestation, analysing changes between different types of vegetation, from evergreen forests to savannas, shrublands, grasslands, croplands and wetlands. However, they found that the removal of tropical evergreen forest for agricultural expansion is the vegetation cover transition most responsible for local increases in surface temperature.

From a greenhouse gas perspective, the cutting of forests might only affect the global climate in the mid-to-long term. However, the scientists point out that local communities living in areas where the trees are cut will immediately be exposed to rising temperatures.

The findings are published in Nature Communications.

Source: European Commission Joint Research Centre [February 20, 2018]