Where weird plants thrive: aridity spurs diversity of traits

Nick Petrić Howe

Welcome back to the Nature Podcast, this week: an unexpected kind of diversity in drylands…

Emily Bates

…and what the hottest temperatures for centuries mean for the Great Barrier Reef. I’m Emily Bates.

Nick Petrić Howe

And I'm Nick Petrić Howe.

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Nick Petrić Howe

As the world warms, many parts of it are also getting dryer. And as environments become more arid, the number of species of plants that live there decline — as the harsh environment means few of them can survive. But things may not be quite that simple, as while species number declines, according to a new Nature study something known as trait diversity increases — challenging a prevailing concept for how ecosystems function. To find out more, I called up one of the study authors, Nicolas Gross, and started by asking him what is this trait diversity?

Nicolas Gross

So, trait diversity is basically any attribute you can measure on an organism that are direct or indirect relationship with its performance in his natural environment. So for a plant, it might be photosynthetic rates, it might be the size of the plant, the shape of the plants, but also any physiological attributes related to its functioning.

Nick Petrić Howe

So what was known before your study then on how trait diversity varies in different environments?

Nicolas Gross

It’s been, I think, 20 years that people focus a lot on trait diversity because they are important parameter to explain how plants or any organisms, animals respond to their environment. And there have been the development of global trait database to describe the diversity of form and function in the natural world. And this global effort have been very intensive, but they are focused on more agricultural and temperate systems. Our study focus on dry lands, which cover 45% of terrestrial areas, and in this global database, there are only 10% of the trait records that come from this environment. So, drylands are highly underrepresented in this global database. There are different reasons for this, but our study was to explore for the first time at the very global scale, how are the plants in this dry environment?

Nick Petrić Howe

And what were your expectations going into this?

Nicolas Gross

There are two main hypotheses. One expectation, it's a very influential hypothesis in ecology, and this concept state that plants should adapt to their environment, especially the abiotic environment — so the rainfall, the drought of this environment — and this filtering will select the most adapt plant to this extreme environment. So according to this hypothesis, we should expect a reduction of trait diversity, because only the most adapt plant to extreme drought, extreme heat, but also grazing would persist in this extreme environment. But when we think about dryland, you often think about also the diversity of shapes of plants you find. You have cactus, you have baobabs, you have a range of different variety of plants, and they are known to be highly diverse. So there was a kind of paradox, and we explored this paradox.

Nick Petrić Howe

And so you looked at, I think, over 300 different plant species across the world in these drylands, what did you find?

Nicolas Gross

The idea of the project was to create a large collaboration network with 121 scientists from 27 countries, and we set a standardised protocol. So, we had this exact protocol to measure the trait diversity of the plant. And so we select more than 326 plots all over the world. And surprisingly, what we found is we found a global increase in trait diversity as aridity or grazing pressure increased. So that was quite an interesting result. And we found that in the most arid places, trait diversity was twice the diversity you can find in the more temperate areas.

Nick Petrić Howe

And was this a straight correlation, like the drier a place got, the more trait diversity there was? Or was there some places where it was more at certain thresholds, I guess?

Nicolas Gross

The main pattern was that the trait diversity response to aridity was non-linear, and this was a very interesting aspect of the study, because we were able to explain why trait diversity increased. So the trait diversity did not change until you reach a certain threshold of aridity. So when you surpass 400 millimeter of rain, we found an abrupt increase, a doubling increase of diversity there. And in the previous study, we found that in these specific areas at the global scale, we observe a collapse of soil fertility and a collapse of plant cover. Because when you think about dryland, you think about landscape with a lot of bare soil and vegetation patches. Okay. And so we found that the global increase of trait diversity occur exactly where we have this collapse of plant cover. And so this allows us to test specifically the relationship between plant cover and trait diversity, and we found that plant cover explained very well the change in trait diversity. And we found that in fact, what filter the trait diversity at the global scale is not a biotic environment might be the competition between plants. So to persist in a competitive environment, you need a certain set of traits combination. And if you have weird combination of traits, these plant species cannot tolerate the having neighbours.

Nick Petrić Howe

And so, you know, the world is under a lot of pressure, like biodiversity is under a lot of pressure, climate change is changing a lot of things. What do you think this understanding does to sort of help us understand how the world might cope with such changes?

Nicolas Gross

Well, first, it says that dryland might be a reservoir of global adaptation, because we have a lot of strategies there. And this is somehow nice, because it seems that even if you go to this extreme environment, you can still have a persistence of a wide range of plant adaptation and diversity. But the thing is that when you look at the local scale, you have less species in dryland than in more temperate species. So you have a collapse of species richness. What we say is that when you take two plants in a very arid environment compared to two plants in the temperate system, the two plants will look very different in dryland, and they will look more similar in a more temperate system. So ecological research have said that on the ecosystem to function, you need a lot of species. In dryland, you do not have a lot of species. But there is this idea that to have a healthy ecosystem, you need a lot of trait diversity. And our studies say quite the opposite, because where plants are too different, they may not interact very well. And to have a healthy ecosystem, you need species that interact in a proper way. So instead of being a signature of a healthy ecosystem, having a wide range of trade diversity might be a signature of an ecosystem that do not function well.

Nick Petrić Howe

That was Nicolas Gross, from INRAE in France. For more on that story, check out the show notes for some links.

Emily Bates

Coming up, scientists have revealed that the Great Barrier Reef has experienced the hottest temperatures for 400 years. Right now, though, it’s time for the Research Highlights with Dan Fox.

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Dan Fox

Butterflies and moths attract a lot of attention with their striking patterns and bright colors. But attention isn't all they attract. Researchers have found that they accumulate static electricity as they fly drawing pollen onto their charged bodies as a result. Scientists already knew that bees and hummingbirds accumulate static electricity while flying, but it has been unclear whether other pollinators do the same. Now, researchers have measured the electrostatic charge of dozens of butterflies and moths from 11 species, as they flew through a ring-shaped electrode. They found that the amount of charge different species collect depends on their environment and lifestyle. Some species develop high charges that boosts their efficiency as pollinators, whereas others carry minimal charge, possibly to avoid night-time predators. If that research has you feeling charged up, you can read it in the Journal of the Royal Society Interface.

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Dan Fox

General relativity says it should be possible to form a black hole from light alone. Now, a new study says that quantum physics rules that out. Black holes form when extremely dense matter collapses under gravity. Because energy and mass are equivalent, physicists have theorized that black holes could also form with high enough concentrations of light. Some have speculated that these holes —termed kugelblitz, after the German for “ball lightning” — could be dark-matter candidates or even power future space travel. Now, researchers have modelled how a kugelblitz might form and found that as intense light is channeled into a sphere, the spontaneous formation of particles and anti-particles predicted by quantum physics draws away energy. The authors demonstrated that to overcome this energy leakage and create a kugelblitz would require a power source about 40 orders of magnitude stronger than the Universe's most extreme energy flares, suggesting that these black holes composed of light are impossible. If you've been caught in the gravity of this research, you can read it in full in Physical Review Letters.

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Nick Petrić Howe

Next up, I’ve been chatting with reporter Jeff Tollefson about record-breaking temperatures affecting the Great Barrier Reef. He joins me now. Hi Jeff, thanks for coming on the show.

Jeff Tollefson

Thank you, Nick. Good to be here.

Nick Petrić Howe

So there's a new paper coming out in Nature about some extreme temperatures affecting the Great Barrier Reef. But before we talk about the paper specifically, the Reef has been taking a bit of a battering over the past few years, right?

Jeff Tollefson

Yeah. I mean, this year was kind of a record bleaching event. Temperatures all across the reef, from north to south, some like 2300 kilometers, were far warmer than usual. But, you know, in some ways, that's a one-off event. The real problem is that this is the fifth big bleaching event in nine years, and the reef has just been hit more and more frequently. And each time it gets hit, it loses a little bit of resiliency and a little bit of diversity.

Nick Petrić Howe

And this paper basically seems to show the temperatures that have been affecting the reef for a really long period. But as you say, we've seen these sort of bleaching events happen quite frequently. So I wonder, what is the value of sort of looking into the past about this, when we can see it sort of happening in real time?

Jeff Tollefson

Yeah. I mean, that's a good question. As scientists, I think we're always interested in data, and we're always interested in having the long record and being able to say with confidence what is and is not new. And if you look at this record, it's more than 400 years, 407 years to be precise, gathered from kind of coral skeletons going back a long way and then overlaying with the actual temperature records over the last century. If you look at that record, what you see is something we're all familiar with. You know, lots of ups and downs in the early years, but generally cooler. You start to see temperatures go up in the 1900s and then over the past few decades, they skyrocket. This is exactly what's happened with global temperatures. It's not necessarily a surprise, but it is good to have the data.

Nick Petrić Howe

And so you mentioned there that this has been done with corals, skeletons and things. Can you just tell me a little bit more about how they've actually got this data set together? Because, as you said, this is over 400 years, which is way before we started keeping records for this sort of thing.

Jeff Tollefson

Yeah that's correct. I mean, they went out to something like 22 locations, and they drilled cores through some of the oldest corals that they could find. Once you have those skeletons, they act a little bit like tree rings in that they record the conditions that were around them when they were growing. In this particular case, the scientists were looking at the ratio of strontium and calcium as well as oxygen isotopes. And if you run this analysis, you can actually determine water temperatures at the time that these corals were growing. So it's a proxy measure, but it's one that's been fairly well established.

Nick Petrić Howe

And so you know, with this big data set, looking at all these coals across the reef, they've shown that the past decade has been particularly warm for these coals, right?

Jeff Tollefson

Yeah, if you look at the five kind of warmest years or six warmest years on record, five of them are all in the last nine years, and all five of those are years where we had mass bleaching events on the reef. And of course, it may come as no surprise, but you know, last year was the hottest year on record for the planet Earth. This was a global bleaching event that started in Northern Hemisphere and then moved south. And what we saw in Australia, on the Great Barrier Reef was, you know, record-setting temperatures across there. And in this record, 2024 was the hottest year by far of the entire 407-year record.

Nick Petrić Howe

I mean, those are quite startling numbers. What do researchers believe this means for the reef?

Jeff Tollefson

Well, I mean, it fits into a larger pattern starting in the 80s but then, kind of in particular, from the big El Nino event in 1997/98 we started seeing these mass bleaching events. You know, prior to that, nobody had ever heard of it. So what the temperatures mean, what the warmer temperatures mean is that these corals are struggling, and we see that every time they bleach. You know, this is basically stressed corals kicking out algae that they depend on for nutrients and color. So when the corals get too hot, they bleach, and some of them may die, some of them may recover, but what it really is, is just an indication that this reef can't handle the kind of temperatures that we're throwing at it. And the scary thing is that there's no indication that these temperatures are going to go anywhere but up in the future.

Nick Petrić Howe

And so we've talked a lot about the temperatures that they found in this study, but they also did an amount of modeling as well, right?

Jeff Tollefson

Yeah, that's right. I mean, you know, one of the big questions that's always out there is how much of this is due to human-induced climate change? The greenhouse gasses that humans have emitted since the Industrial Revolution. And, you know, scientists have pretty good and established methods for running these types of tests today. So in this case, they, you know, spun up some climate models, plugged greenhouse gas emissions, historical greenhouse gas emissions, into one and ran another without any greenhouse gas emissions. Just looking at, you know, what the world might have looked like without human beings pumping fossil carbon into the atmosphere. And what you see again is not entirely surprising. What you see is that– that it's hard to kind of produce these types of changes in ocean temperatures without human greenhouse gas emissions. If you run these models just under natural circumstances, you don't tend to get this kind of warming. And what that tells you is that you know almost certainly climate change is playing a role. And what that also tells you is that the worse climate change gets, the higher the temperatures are going to rise, and the harder it's going to be for the reef.

Nick Petrić Howe

And you know, the Great Barrier Reef is sort of this bastion of biodiversity. I guess it's a real landmark of the health of planet Earth, I guess. So what do you think this sort of spells for the future?

Jeff Tollefson

Well, you know, this is one iconic ecosystem, and in some ways, one might think that if any reef is able to kind of adapt and handle the types of challenges that we're throwing at it, it might be this one, because it's big, it's diverse, it's got a lot of different types of coral. So all of those things help in a lot of places. You know, you've got smaller reefs that don't have the kind of diversity and geographic scale to be able to adapt. So if the Great Barrier Reef is having trouble, then probably we're in trouble with all of our corals, unfortunately. And I guess the next question is, what are we going to be left with if we don't reduce our greenhouse gas emissions in the coming decades? And that is so far an open question. There are some indications, if you talk to scientists, that you know the reefs will adapt in certain ways, maybe not in ways that we like. Maybe they won't be as colorful, maybe they won't be as diverse, but you know, maybe some hardy corals will survive, and maybe the reefs will keep providing the kind of services that we have come to kind of expect from them, including protection from storm surges and fisheries and tourism. But that's an open question, you know. All we can say at this point is the future doesn't look very good for the reefs the way that we know them today, probably something's going to change.

Nick Petrić Howe

That was Jeff Tollefson, for more on this story check out the show notes for some links.

Emily Bates

Finally, on the show, as the briefing is taking a bit of a summer break, we've got something a bit different for you. Reporter Max Kozlov has been playing a game that we think will be of interest to many academics. Take it away, Max.

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Max Kozlov

I'm a bit embarrassed to admit it, but one of those targeted ads you see online just caught me. Normally, I like to think of myself as someone who would never fall prey to advertising, but something about this clip I saw on Instagram just grabbed me.

Game Clip

Welcome to the chaotic life of academic publishing. In this game, you are a clueless researcher trying to do the one and only thing that matters in your academic life: turning out publications fast.

Max Kozlov

This is the sound of me and some colleagues trying out Publish or Perish, the board game that stopped my thumb in its tracks as I was mindlessly scrolling through Instagram.

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Max Kozlov

You can probably guess why a science journalist who's a big fan of board games might have been caught by this ad.

Game Clip

So you will publish useless nonsense, sabotage your colleagues research and provide unhelpful comments, “Reviewer 2” style. Your goal is to gain as many citations as possible when the game ends. Ideally with your sanity and self-respect intact. It's probably no surprise that the game was conceived as a way to vent about the stress that academics experience.

Max Bai

The problem I ideally wanted to solve is like to create a medium for people to socialize using the collective trauma people are experiencing in academic life.

Max Kozlov

This is Max Bai the creator of Publisher or Perish.

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Max Kozlov

As an academic himself, he's very familiar with many of the challenges that academics face and was excited to put them into the game. For example…

Max Bai

The difficulty dealing with the reviewing process.

Game Clip

You basically scooped my idea, then just like flourish the language and everything, and say–

–look Nature–

–look at my citation–

–it’s the same paper–

–got published in Nature is all I'm saying.

Max Bai

Hard time of finding your PI when you really need something to go forward–

Game Clip

–auto-reply reply your email is very important to me. I'll ignore it upon my return.

Max Bai

Difficulty in secure funding.

Game Clip

This is a research-grant card. Funding received. Finally, you can stop using your crayons for your graphs.

Max Bai

Yeah, it has just like the whole enchiladas. There's so many things to make fun of.

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Max Kozlov

The game is pretty simple. It's a card game where you try to publish as many journal articles as possible, first by racking up research cards and using them to publish manuscript cards. And when you publish them, then the most important rule comes into force.

Game Clip

When somebody publishes, it's important to announce, quote, unquote, I am publishing, and then you insert the title of the manuscript that you've just published. Everyone else must say congratulations on your publication while clapping.

Max Kozlov

The end goal is to publish five manuscripts and then defend your research program, something that isn't always easy when your publications can range from “echo chambers and ivory towers the acoustics of academic isolation” to “unpacking the aerodynamics of flying pigs”. Meanwhile, you have to contend with other players. Across the world, many academics live in fear of “Reviewer 2”. There's a standing joke that whenever a manuscript is submitted, there's always that one reviewer who's extra nitpicky. And so, the game has a special award that's worth extra citations for the player that most embodies this infamous “Reviewer 2”.

Game Clip

I mean, you published in the current directions in Xeno cultural studies. I mean, is that even a real journal?

Big impact factor–

–what's the impact factor?–

–100–

–paper mill right there–

Max Kozlov

They can also spring upon you the kind of mishaps that are probably familiar to most academics.

Game Clip

I'm gonna use the ‘wrath of reviewer 2’. Reviewer 2 had a bad breakup right before reviewing your manuscript. Rest in peace for resubmission.

Max Kozlov

But despite creating this game to help people bond over the travails of academic life. Max still believes that academia has some redeeming qualities and thinks the game can also showcase that. For example, as well as cards to foil other players plans, there are also helpful cards like collaboration.

Max Bai

So the fact of that card is like, you pick three cards, you have someone else pick one they want and you retain the two. So like both of you will get something good out of it.

Max Kozlov

When I was playing, I had a great time with the game. The ridiculous manuscript titles and action cards were entertaining. But at the same time, I do wonder how much fun it would be for someone unfamiliar with academia, because in the end, it's a game of inside jokes. For me, that was the whole reason to play. But if you're not on the inside, then I don't know how much appeal it would hold, as there wasn't a particularly captivating game mechanic or strategy you had to employ. So, it's one to play with the lab and poke fun at the strange world of academia. But Max does believe that there is a serious point to be made about academic publishing culture as well.

Max Bai

I think the current academic publishing culture is almost toxic in many ways, and we know for a fact from just research that graduate student, early-career scholar, like the burnout rate is just abnormally high. We've seen in a profession that people collectively experience at that level stress and trauma, then there is a problem here, and Publish or Perish culture is definitely something that play a big role in here.

Max Kozlov

In the end, while this game can't solve the real problems of publish or perish, maybe it can at least help academics laugh through it.

Game Clip

I am going to publish one more.

Congratulations–

–the etiquette of eating noisy food in quiet places–

–that's funny.

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Emily Bates

Nature’s Max Kozlov there. You also heard from Max Bai, from the Political Belief Lab, in the US. For more on Publish or Perish check out the show notes for a link to Max Kozlov’s story.

Nick Petrić Howe

And that’s it for the show. But not all for this week, we’ve got a podcast and a video coming out this Friday where I’ve been finding out how chatbots like ChatGPT perform in different languages. Check out your podcast feed and our YouTube channel for that!

Emily Bates

In the meantime, you can keep in touch with us on X, we’re @NaturePodcast, or you can send us an email to podcast@nature.com. I’m Emily Bates.

Nick Petrić Howe

And I’m Nick Petrić Howe. Thanks for listening.