Features

Gijsbert Werner, Postdoctoral Fellow and Stuart West, Professor of Evolutionary Biology, both in the Department of Zoology, explain the process of plant cooperation, in relation to their new study published in PNAS, which has shed light on why cooperative relationships breakdown.

Unseen to most of us, almost all plants form below-ground interactions with beneficial soil microbes. One of the most important of these partnerships is an interaction between plant roots and a type of soil fungi called arbuscular mycorrhizal fungi.

The fungi form a network in the soil and provide the plant with soil minerals, such as phosphorus and nitrogen. In return, the fungi receive sugars from the plant. This cooperation between plants and fungi is crucial for plant growth, including of many crops. Plants sometimes even get up to 90% of their phosphorus from these soil fungi.

In collaboration with a team of international researchers, we set out to better understand plant cooperation. We wanted to know why some relationships of plants with soil fungi flourish and others collapse.

This involved analysing a large database of plant-fungal interactions containing thousands of species and using computer models to reconstruct the evolutionary history of the partnership. We found that despite having successfully cooperated for over 350 million of years, partnerships among plants and soil fungi can break down completely.

Once we knew that that plant-fungus cooperation could fail, we wanted to understand how and why the relationship breaks down. We found that in most cases the plants were replacing the fungi with another cooperative partner who did the same job, either different fungi or bacteria. In the other cases, plants had evolved an entirely different way of obtaining the required minerals – for instance, they had become carnivorous plants which trap and eat insects.

Our study shows that despite the great potential benefits of the relationship, cooperation between plants and fungi has been lost about 25 times. It is quite crazy that such an important and ancient collaboration has been abandoned so many times. So why did this happen?

One explanation is that in in some environments, other partners or strategies are a more efficient sources of nitrogen or phosphorus, driving a breakdown of previously successful cooperation between plants and fungi.

For instance, carnivorous plants are often found in very nutrient-poor bogs. Even an ancient beneficial fungus, specialised in efficiently shuttling nutrients to their partner plants simply cannot get the job done there. So, plants evolve a different way to get their nutrients: trapping insects.

A next step is to now find out in what conditions the various different nutrient strategies are found? Where on our planet do plants keep their original fungi? Where do they go for another solution to get their nutrients? Other work focuses on the potential that some fungi evolve to become ‘cheaters’ - taking the benefit from the partnership but no longer contributing to it and ultimately driving its breakdown.

Francesca Moll meets the academics hoping to heal divisions in modern society using a 16th-century work of speculative fiction.

There once was an island that was connected to a larger continent by a small but significant link. But then one day the citizens of this island decided to irrevocably separate themselves from the mainland, in order to pursue a dramatic and some might say unrealistic vision of a better society.

An accurate representation of Britain's current political situation? Actually, it's the premise of Thomas More's Utopia, a hugely influential early modern political treatise published exactly 500 years before the momentous Brexit referendum last June. But now this centuries-old story of a fictional social experiment is feeling eerily relevant.

According to Oxford's Wes Williams, Professor of French Literature and Fellow of St Edmund Hall, and Richard Scholar, Professor of French and Comparative Literature and Tutor at Oriel College, More's work still has some important lessons for modern society. They are collaborating on an innovative theatrical production, Storming Utopia, a 'mashup' of More's Utopia and Shakespeare's The Tempest.

An 'experiment in practical utopianism', the project aims to break down boundaries of age, class, race and gender in Oxford, bringing together a socially and ethnically diverse cast ranging in age from seven to 67 to ask what would make a better society.

Storming Utopia is also looking to build bridges between England and Europe. Jointly funded by a Knowledge Exchange Fellowship from TORCH (The Oxford Research Centre in the Humanities) and money set aside to fund collaboration between TORCH and the Cini Foundation in Venice, the production is also performed in Italian at the foundation's headquarters on the island of San Giorgio Maggiore.

Throughout, the play asks the question: 'If there was one thing you could change about the place you could live, what would it be?', prompting responses from the cast and audience. These have varied from making university libraries accessible to the general public, to scrapping private education, to radically reconstituting the nuclear family. One of the more creative ideas suggested flooding Oxford and turning the streets into Venice-like canals, to solve the city's notorious parking and traffic problems.

But as well as imaginative dreaming, Storming Utopia has also tackled bitter post-Brexit political divisions. This was particularly important to younger members of the cast, to express the anger and powerlessness they felt post-referendum.

'Everybody in the show who was under 18 had a really strong sense that their future had been taken away from them. And that they had no say in it. One of the young people in the show said: "What's been really great about this show is it's given us a voice that we don't otherwise have,"' says Professor Williams.

However, as theatre, Storming Utopia ensured that the representation of Brexit – after all, a kind of Utopian vision – was not only one-sided. Throughout the play several characters – including Boris Johnson – argue the case in favour. According to Professor Williams, the intention was to build bridges, not create greater divisions, and so it was important to explore a diversity of experiences and opinions. He says: 'Brexit is much a symptom as a cause, and Brexit is a symptom of divisions, boundaries, walls within British society.'

But at least within the small group of 21 individuals in the company, the project seems to be overcoming some of these deep divisions. Many of the actors, who have lived side by side in Oxford for years without getting to know one another, have formed close personal friendships across boundaries of age, social class, ethnicity and university or non-university affiliation.

Most rewarding was the chance to confront the deep generational divide becoming ever more present in politics, bringing together people decades apart in age and giving them a chance to learn from each other's different experiences.

Professor Williams says: 'You might think the main thing would be ethnic diversity, or perhaps religion, amongst all the various things that we think of as somehow determining difference. But actually it really was age that people talked about when we asked them what they learnt from this project. We constitute ourselves as little islands of age, and as we grow older, we take our little island of oldness with us.' 

Professor Williams believes this shows that there is the potential to overcome even the most intractable of differences. 'In terms of what I'd like people to take away from the play, I think hope. Hope in the possibility of community, of people working together to make stuff happen. A bit of rage at the current state of affairs. But mostly Utopian hope.'

Professor Scholar agrees. 'I think that Storming Utopia has been a genuinely Utopian project, the bringing together and sharing in common of an experience involving people who wouldn't otherwise have had that chance. I count myself very lucky to have been a part of it.'

This blog post is adapted from an article published by the Gemini Observatory.

Even after decades of observations, and a visit by the Voyager 2 spacecraft, Uranus held on to one critical secret: the composition of its clouds. Now, one of the key components has finally been verified.

Professor Patrick Irwin from the University of Oxford's Department of Physics and global collaborators spectroscopically dissected the infrared light from Uranus captured by the eight-meter Gemini North telescope on Hawaii's Maunakea. They found hydrogen sulfide, the odiferous gas that most people avoid, in Uranus’s cloud tops. The long-sought evidence is published in the journal Nature Astronomy.

The Gemini data, obtained with the Near-Infrared Integral Field Spectrometer (NIFS), sampled reflected sunlight from a region immediately above the main visible cloud layer in Uranus's atmosphere. Professor Irwin said: 'While the lines we were trying to detect were just barely there, we were able to detect them unambiguously thanks to the sensitivity of NIFS on Gemini, combined with the exquisite conditions on Maunakea. Although we knew these lines would be at the edge of detection, I decided to have a crack at looking for them in the Gemini data we had acquired.'

Dr Chris Davis of the United States' National Science Foundation, a funder of the Gemini telescope, said: 'This work is a strikingly innovative use of an instrument originally designed to study the explosive environments around huge black holes at the centres of distant galaxies. To use NIFS to solve a longstanding mystery in our own solar system is a powerful extension of its use.'

Astronomers have long debated the composition of Uranus’s clouds and whether hydrogen sulfide or ammonia dominates the cloud deck, but lacked definitive evidence either way. Professor Irwin said: 'Now, thanks to improved hydrogen sulfide absorption-line data and the wonderful Gemini spectra, we have the fingerprint which caught the culprit.' The spectroscopic absorption lines (where the gas absorbs some of the infrared light from reflected sunlight) are especially weak and challenging to detect, according to Professor Irwin.

The detection of hydrogen sulfide high in Uranus's cloud deck (and presumably Neptune’s) contrasts sharply with the inner gas giant planets, Jupiter and Saturn, where no hydrogen sulfide is seen above the clouds, but instead ammonia is observed. The bulk of Jupiter and Saturn's upper clouds are comprised of ammonia ice, but it seems this is not the case for Uranus. These differences in atmospheric composition shed light on questions about the planets' formation and history.

Dr Leigh Fletcher, a member of the research team from the University of Leicester, adds that the differences between the cloud decks of the gas giants (Jupiter and Saturn), and the ice giants (Uranus and Neptune), were likely imprinted way back during the birth of these worlds. He said: 'During our solar system’s formation, the balance between nitrogen and sulphur – and hence ammonia and Uranus's newly detected hydrogen sulphide – was determined by the temperature and location of planet's formation.'

Another factor in the early formation of Uranus is the strong evidence that our solar system's giant planets likely migrated from where they initially formed. Therefore, confirming this composition information is invaluable in understanding Uranus's birthplace, evolution and refining models of planetary migrations.

According to Dr Fletcher, when a cloud deck forms by condensation, it locks away the cloud-forming gas in a deep internal reservoir, hidden away beneath the levels that we can usually see with our telescopes. He said: 'Only a tiny amount remains above the clouds as a saturated vapour. And this is why it is so challenging to capture the signatures of ammonia and hydrogen sulfide above cloud decks of Uranus. The superior capabilities of Gemini finally gave us that lucky break.'

Dr Glenn Orton of NASA's Jet Propulsion Laboratory, another member of the research team, said: 'We've strongly suspected that hydrogen sulfide gas was influencing the millimetre and radio spectrum of Uranus for some time, but we were unable to attribute the absorption needed to identify it positively. Now, that part of the puzzle is falling into place as well.'

While the results set a lower limit to the amount of hydrogen sulfide around Uranus, it is interesting to speculate what the effects would be on humans even at these concentrations. Professor Irwin said: 'If an unfortunate human were ever to descend through Uranus's clouds, they would be met with very unpleasant and odiferous conditions. However, suffocation and exposure in the -200C atmosphere made of mostly hydrogen, helium and methane would take its toll long before the smell.'

The new findings indicate that although the atmosphere might be unpleasant for humans, this far-flung world is fertile ground for probing the early history of our solar system and perhaps understanding the physical conditions on other large, icy worlds orbiting the stars beyond our Sun.

In a study of 11 different plant species, published in Molecular Biology and Evolution, researchers at the University of Oxford have shown that the speed at which plants evolve is linked to how good they are at photosynthesis.

The team from the Oxford Department of Plant Sciences detected differences in plant gene evolution that could be attributed to how good or bad those plants were at photosynthesis.

Plants need nitrogen to do photosynthesis. They use it to build the proteins they need to turn atmospheric CO2 into sugars. However, plants also need nitrogen to build their genes, and the different letters in DNA cost different amount of nitrogen to make - A and G are expensive while C and T are cheaper. What the study found is that plants that invest lots of nitrogen in photosynthesis use cheaper letters to build their genes. This molecular “penny-pinching” restrains the rate at which genes evolve and so plants that spend a lot of nitrogen on photosynthesis evolve more slowly.

The study provides a novel link between photosynthesis and plant evolution that can help explain why the number of plant species is unevenly distributed across the globe. It also helps to explain why plants that are highly efficient at photosynthesis form new species faster than plants with lower efficiency.

Lead author, Dr Steven Kelly, from Oxford’s Department of Plant Sciences, said: 'These results also allow us to make predictions about how plants evolve in response to a changing climate. For example, when atmospheric CO2 concentration goes up, plants don’t need to invest as much nitrogen in trying to capture it, and so more of the nitrogen budget in the cell can be spent on making genes. That means when atmospheric CO2 concentration goes up plant genes evolve faster.’

Is it possible to use natural resources effectively and protect the Earth's wildlife and biodiversity? Oxford University scientists have proposed a new framework that could achieve exactly that. William Arlidge, a doctoral student and Professor EJ Milner-Gulland, Tasso Leventis Professor of Biodiversity; Director, Interdisciplinary Centre for Conservation Science; Fellow of Merton College, discuss their new research as featured in BioScience.

In an effort to help answer one of the biggest questions in conservation,  in our new paper we discuss whether a framework used to reduce negative impacts from development on biodiversity could be expanded to account for all human impacts on nature. 

Biodiversity is the variety of life in all its forms on planet Earth. It’s a broad concept, and conserving it is complex as it needs multifaceted approaches that are aimed at understanding what is most valuable, and at most risk, and what are the best approaches to undertake conservation that is not at odds with other societal needs. Our current efforts to do so comprise a patchwork of international goals, national plans, and local interventions. While our conservation efforts are not without great successes, overall, they are failing to achieve all their desired outcomes. This is largely down to us, because human needs for ever-more space to grow food, harvest wild products like timber and fish, and build infrastructure, are squeezing out nature.

Our continued use of biodiversity to improve our wellbeing is, sadly, all too often in conflict with our efforts to conserve it. At the broadest scale the United Nations Sustainable Development Goals provide a global vision to conserve and sustainably use biodiversity, however guidance on how this broad vision translates to actions at national, regional, and local levels is not clear.

In our new publication, we propose taking a more systematic approach to achieving biodiversity conservation goals, by accounting for all human biodiversity impacts and conservation efforts within a unified global framework.

This framework expands on an existing concept known as the ‘mitigation hierarchy’, which offers a balanced and systematic way to account for and mitigate harmful impacts to biodiversity, while still allowing development activities to occur.

The mitigation hierarchy works by first trying to predict all the negative impacts that are likely to occur as part of a given activity. Creating a palm oil plantation, for example, will mean directly losing some tropical forested areas and their associated biodiversity. There will also be other more indirect impacts such as the risk of sedimentation, pollution and noise disturbance. To account for all these different impacts, sequential steps are taken: developers need first to consider the extent to which they can avoid causing damage. Then they need to minimise the damage they cause from their operations. Next, they should remediate any temporary damage. All these steps mitigate biodiversity impacts on site. Following the implementation of these steps, any residual impacts to biodiversity not mitigated must be offset by boosting biodiversity elsewhere.

Avoiding impacts could include selecting sites that have no biodiversity impact or foregoing the development effort all together. Minimisation could include restricting heavy machinery used to remove palm oil to particular roadways and halting construction during sensitive times. Remediation could include reinstating roads to their previous condition once they are finished with. Offsetting might include replanting forest habitat elsewhere. The logic in undertaking these steps is to achieve a neutral or positive level of impact to biodiversity after a given damaging activity (often referred to as ‘No Net Loss’ or a ‘Net Gain’ of biodiversity).

While the theoretical and practical challenges in achieving No Net Loss of biodiversity are becoming increasingly well described and reported (see papers from Joe Bull, Martine Maron, and David Lindenmayer), the underlying concept of the mitigation hierarchy is both powerful and much more widely applicable than has so far been appreciated.

Currently there is a widespread and piecemeal project-level approach to achieving No Net Loss of biodiversity taking place. This means that, if biodiversity gains and losses were to be aggregated, biodiversity could be lost even if individual projects appear to be reaching their targets. If the concept is to truly have biodiversity benefits, there is a need for a multi-scale approach to No Net Loss, so that wider goals are not contradicted by project-level use of the mitigation hierarchy.

In our publication we propose the use of the mitigation hierarchy to navigate the conservation-development trade-off at the broadest scale possible, the whole planet. Incorporating all human impacts on biodiversity within the single standardised paradigm with a broad biodiversity conservation goal. Crucially, a global mitigation hierarchy offers a systematic framework that is both scalable from the project to the national and international levels, as well as being standardised between the conservation sectors of sustainable use (e.g., certification schemes), minimising the impact of development (e.g., No Net Loss), and efforts to directly restore or protect sites (e.g., protected areas).

Conserving biodiversity while simultaneously seeking to use it for humanity's needs is a huge challenge, which some suggest is not possible on our current growth trajectory. Others have called for half the planet to be set aside for biodiversity conservation, or for more space to be given to nature. But in the absence of a clear pathway to achieving it, it is difficult to see how these aspirations can translate into real biodiversity gains. Our approach cannot solve all of these challenges, but what the mitigation hierarchy offers is transparency, enabling clear understanding of what the consequences of various uses of nature are, with flexibility to address a variety of human impacts on biodiversity, across different sectors and scales.

Fundamental changes are needed if humanity is to reverse the current biodiversity crisis and put the planet on a sustainable course for the future. However, these changes will only be possible if we can see a way forward. Quantifying and accounting for all human-caused impacts to biodiversity could help humanity to reduce these impacts in a feasible and equitable way. A global mitigation hierarchy could be the first step towards achieving such a vision.