NATURE PODCAST

Podcast: Non-native species, and a blood-inspired robot battery

Benjamin Thompson and Shamini Bundell bring you the latest science updates.

This week, what makes birds invasive, and a robotic fish powered by a blood-like battery.

In this episode:

00:44 How do alien bird species establish themselves?

Researchers have been looking at how bird species settle in non-native locations. Research article: Redding et al.

08:22 Research Highlights

Crafting the perfect crêpe, and anti-fungal wasp eggs. Research Highlight: Physicists tackle a delicate challenge: making the ideal crêpe; Research article: Strohm et al.

10:09 Robot blood

Multipurpose battery fluid both moves and powers a robot fish. Research article: Aubin et al.; News: Robo-fish powered by battery ‘blood’

16:30 News Chat

Researchers reviewing misconduct investigations, and redefining pressure. News: What universities can learn from one of science’s biggest frauds; News: Pressure’s 400-year-old measurement techniques get an upgrade

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Transcript

This week, what makes birds invasive, and a robotic fish powered by a blood-like battery.

Host: Benjamin Thompson

Welcome back to the Nature Podcast. This week, we’ll be finding out about alien invasions…

Host: Shamini Bundell

And hearing about robot blood. I’m Shamini Bundell.

Host: Benjamin Thompson

And I’m Benjamin Thompson.

[Jingle]

Interviewer: Benjamin Thompson

Listeners, a title of a paper in this week’s Nature rather caught my eye, and it contains the words ‘alien bird populations’. Now, I did a bit of a double take when I saw it, but I have to say quickly, avian extra-terrestrials have not been discovered – at least as far as I know. In this case, the word ‘alien’ refers to non-native species here on Earth that have been moved to a location where they’re not naturally found. This happens all the time, says David Redding from University College London here in the UK.

Interviewee: David Redding

The commonest animal species that get moved around by people are livestock and that’s happening every minute of every day. Other ways that species are moved are things like accidental movement of, say, mosquitoes in containers where there’s little pools of water, and again, that’s happening all the time on ships. And other times, there have been deliberate attempts to populate other places with, say, familiar species. So, when Britain colonised different areas of the world, they would take British species over with them and introduce them to just feel more familiar and more at home.

Interviewer: Benjamin Thompson

Nowadays, there is a lot of legislation against the deliberate introduction of species, but in this globalised world, accidental introductions happen all the time. As countless historical examples have taught us, introducing species to places beyond where they’re naturally found can have very bad results. When a non-native species becomes established at a new location it can become invasive and cause serious consequences to the local wildlife, environment and economy. Take the rapidly growing plant Japanese knotweed, which is now found all over the world. This species can crowd out other plants and cause damage to things like property. It’s also really hard to eradicate. But non-native species don’t always become established, for reasons that aren’t entirely clear. This week, David and his colleagues have been combining data on a number of factors to get a better idea of what needs to happen for an alien introduction to establish and become an alien invasion. In this case, the team have been looking at birds.

Interviewee: David Redding

One of the real benefits of this group is just the availability of the data. So, we could look at, say, plants that cause a large amount of damage or some insects but the actual information in order to be able to do a kind of robust and in-depth analysis aren’t really there, whereas when we look for birds, we find that people have not only documented, say, the number of goldfinches that got transported on a ship in 1890 to Auckland, we’ve also then got records of people spotting them and recording oh, I saw a flock of 30 goldfinches flying past my window ten years later. So, we’ve got this very rich set of data that are associated with birds because people just have this strong affiliation for them.

Interviewer: Benjamin Thompson

The team went back through the records and identified over 4,000 introduction events spanning over 700 species. A lot of the oldest records were related to the introduction of birds eaten for food, such as the ring-necked pheasant, which was likely introduced to what is now the UK sometime between 1042 and 1066 AD. By combining details on the introduction events with information about the birds’ biology and what the local conditions were like, the team built up a picture of the most important drivers for a non-native species to establish at a new location.

Interviewee: David Redding

Some of the strong drivers seem to be what’s already there, in terms of introduced species. So, we seem to see this worrying relationship where as we have species being introduced from other groups, say rodents or plants, it also seems to facilitate further establishments. Another important driver is the match between the environment that the species has been taken from and where it’s being taken to.

Interviewer: Benjamin Thompson

Although there are a bunch of interplaying drivers, the team suggest that these are two of the strongest. Moving a bird species to a new location with similar conditions to where it came from seems like an obvious one. But how does the presence of other non-native species make it easier for a bird to become established? It’s a bit of a headscratcher, but David’s got some ideas.

Interviewee: David Redding

It could be that introduced species have disturbed or broken up the natural order and that we have fewer predators or we don’t see the sort of dominant canopy species that normally shade out light and so there’s more gaps in the habitat that means that other species can then come in and use.

Interviewer: Benjamin Thompson

David said that their analysis threw up some secondary drivers as well, such as how many offspring the bird species produce and the size of the initial founding population. So, if there are so many factors, what’s the perfect storm for a non-native bird species to establish?

Interviewee: David Redding

I guess the perfect situation is to be bringing in hundreds of individuals. It needs to have species that live quite a long time and have babies quite quickly but not too quickly. They need to be able to eat lots of different things and be able to use lots of different habitats and I guess they need to be introduced to locations that suit them.

Interviewer: Benjamin Thompson

Elizabeta Briski from the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany works on the invasive ecology of marine species and wasn’t involved in this study. She was impressed by its findings, but thinks that future work could look at other groups of organisms to get an even better idea of how non-native species can become established.

Interviewee: Elizabeta Briski

I think the work is excellent. What I think should be done more is, for example, it’s done on birds. For birds, we have a very extensive and very broad dataset but this is also a small disadvantage because why we have all this data, because many of the birds are intentionally introduced. But what is the problem that we are introducing species then we are choosing certain characteristics. This doesn’t represent a natural situation and that doesn’t mean that it will always work on accidental introduction and today, the majority of introductions are accidental because today we know that to introduce new species is not good and this is what we are trying to stop.

Interviewer: Benjamin Thompson

Whether or not these introductions can be stopped is a difficult question to answer, but David hopes that by learning more about what makes a species able to establish, future invasions can be prevented.

Interviewee: David Redding

So, what we want to be able to do is proactively stop this when populations are really small because once they’ve established it’s almost impossible or extremely costly to get rid of them, and so, if we’re going to stop that, we’ve got to understand what combinations of species and locations are most at risk.

Interviewer: Benjamin Thompson

That was David Redding from University College London. You also heard from Elizabeta Briski from the GEOMAR Helmholtz Centre for Ocean Research Kiel. You can read David’s paper over at nature.com.

Host: Shamini Bundell

Later in the show, we’ll hear about the researchers who have come up with a new way to define the unit of pressure – the pascal. That’s coming up in the News Chat. Now though, it’s time for the Research Highlights, read this week by Noah Baker.

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Host: Noah Baker

Crêpes are a European favourite. The thin pancakes typically filled with sweet or savoury treats have been delighting us for decades, and now scientists claim to have discovered the perfect way to make them. It’s all in the wrist. They used a mathematical model to work out the best way to move the pan to achieve the crème de la crêpe – uniform in thickness and hole-free. Their modelled method starts with adding the batter and then tilting the pan steeply to move the batter to the edges. Rotating the pan in a circle helps to achieve a full batter coverage. Next, while continuing to circle the pan, slowly decrease the angle of the tilt until it’s level with the heat and the crêpe is cooked. But when do you flip? Try that for yourself over at Physical Review Fluids.

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Beewolves, which are neither bees nor wolves, but a fearsome species of wasp, have developed a unique way to defend their eggs. Beewolves live underground, and that comes with risks. The warm and humid conditions are ideal for fungi to grow which can infect and kill insect eggs. But researchers from Germany noticed a pungent smell coming from the eggs of captive beewolves in their lab. The eggs were releasing nitric oxide, fumigating their underground chamber and killing off invading fungus. The authors believe that understanding this process could lead to new anti-mould treatments. You can defend that research over at eLife.

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Host: Shamini Bundell

We love a good robot here at Nature – you just need to take a look at the Nature Video Channel to see that. This week on the show, reporter Nick Howe has been finding out how taking a leaf out of biology’s book can help us make better bots.

Interviewer: Nick Howe

From being Jedi’s sidekicks, to running our errands, science fiction is rife with descriptions of robots, and they tend to have something in common – they’re not running to a power outlet every five minutes. In other words, they’re autonomous – they don’t need human intervention to function. Outside the realms of science fiction, this is quite difficult to achieve, as making robots more power independent usually means adding more batteries, which means adding more weight, which means they need to use more power to move, which means they need more batteries, which… well, you see where this is going. But this week in Nature, there may be a new method to get around this problem. Many robots move using hydraulic fluids that are compressed and expanded to move their parts, but Rob Shepherd, a roboticist from Cornell University, has been taking inspiration from the natural world to do more with hydraulic fluid, in an attempt to solve the battery problem.

Interviewee: Rob Shepherd

So, the idea came to me when I was thinking about circulatory systems and hearts and pumping blood through a vascular system. Blood supplies energy and our heart is a pump, and our blood is powering our heart. So, then I thought about how we can apply this idea to hydraulic fluids. So, then you would replace the heart with a liquid pump, and that liquid pump would be pumping electrolyte that would power the pump itself.

Interviewer: Nick Howe

This robotic circulatory system would be filled with what Rob calls robot blood. The blood is composed of battery fluid making it multifunctional, both powering and moving the robot. By doing this, energy could be added to the robot without adding extra weight. Multifunctional batteries have been around for a while. For example, in some forklift trucks, heavy batteries are used to counterbalance their loads. But this is the first time hydraulic fluid has been used been used as a battery. To try out this idea, Rob made a soft robot – one that is made from soft parts – that was modelled on a lionfish.

Interviewee: Rob Shepherd

I wish it did look exactly like a lionfish, but a lionfish is very brightly coloured. Ours is actually translucent white because we used a silicone for the shell of the robot. It has some spikes coming off the top like a fin and it has some other fins, like pectoral fins. It has a tail that it can move back and forth.

Interviewer: Nick Howe

Rob told me he didn’t choose this design simply because it looked impressive. The spikes coming out of the top served as a storage area for various components essential for the robot blood to function as a battery. For the blood itself, Rob turned to redox flow batteries, which are composed of fluids used for large scale storage of energy – the perfect ingredients for robot blood. With the fish pumped up with robot blood, Rob set about testing how much energy it could store.

Interviewee: Rob Shepherd

If we use our battery fluid as a hydraulic fluid, it’s 325% more energy dense than it is just using the passive oil or water we would use for hydraulic fluid.

Interviewer: Nick Howe

Being packed with energy meant the robot blood was able to power the fish for a long time, without needing to be recharged. Rob calculated that it could swim for 37 hours before needing a top up. And it could swim… just about.

Interviewee: Rob Shepherd

Ugh, do we have to talk about that? Laughs. In terms of body lengths per second, it was like fractions of a body length per second. It’s moving along pretty slowly. Yeah, it would definitely get eaten if it was in the ocean.

Interviewer: Nick Howe

Okay, it was no Michael Phelps, but according to Rob, that wasn’t the point. It was a proof of concept to see if energy density – the amount of energy stored – could be improved to make robots more autonomous. In that regard, Cecilia Laschi, a roboticist from Scuola Superiore Sant'Anna in Italy, thinks it was a success.

Interviewee: Cecilia Laschi

I found their idea fantastic. It’s a very original idea. It addresses a very important problem and I think that the solution is interesting to start giving an answer for making robots autonomous and useable.

Interviewer: Nick Howe

Cecilia believes that this energy freedom would be very useful, especially in soft robots.

Interviewee: Cecilia Laschi

Being autonomous brings soft robots towards applications in real environments like exploration, search and rescue, even underwater. So, the idea of sending soft robots underwater is also a very good idea to explore the oceans.

Interviewer: Nick Howe

Before we get there though, there’s a way to go. For a start, it could be useful to get robots moving a little bit faster than the fish in this study. Rob thinks this could be achieved using capacitors which would allow the energy stored to be released a lot more quickly. He also thinks that while the energy density in his robot was high, nature still has it beat.

Interviewee: Rob Shepherd

So, the systems energy density of our robot is about 53 joules per gram compared to a human – we have about 11 kilojoules per gram when we use fat. So, even though I think our robot is pretty impressive, we’re still many orders of magnitude away from the energy density of a living organism.

Host: Shamini Bundell

That was Rob Shepherd of Cornell University in the US. You also heard from Cecilia Laschi of Scuola Superiore Sant'Anna in Pisa, Italy. You can find Rob’s paper over at nature.com and if you want to see some pictures of the robot fish, find us on Twitter – @NaturePodcast – where we’ll post some.

Interviewer: Benjamin Thompson

Finally then on this week’s show, it’s time, of course, for the News Chat and joining me here in the studio is Nisha Gaind, Nature’s European Bureau Chief. Nisha, hi.

Interviewee: Nisha Gaind

Hi, Ben.

Interviewer: Benjamin Thompson

Well, our first story then, it’s about research misconduct.

Interviewee: Nisha Gaind

Yes, this is a story not about just a research misconduct case, but also an investigation that has looked at this research misconduct case and more specifically, how universities investigated it.

Interviewer: Benjamin Thompson

Right, so a review of how misconduct cases are looked at.

Interviewee: Nisha Gaind

Yes, so the fantastically interesting thing about this is that this is one of the biggest research misconduct cases that science has ever seen. It involves a researcher who has now died. His name is Yoshihiro Sato and he was a bone-health researcher in Japan and over the course of about two decades, he fabricated data, he forged authorships, he plagiarised work, and that has now led to the retraction of more than 60 of his studies from the literature.

Interviewer: Benjamin Thompson

Well, how does this relate to how misconduct investigations are undertaken then?

Interviewee: Nisha Gaind

So, this story is about a team of researchers who has become rather obsessed with this case. They are in the same field and they are among the researchers who had initially flagged concerns about many of these research papers, and because it’s such a sprawling case of misconduct, it has actually been investigated by quite a few institutions around the world. And our story looks at the analysis that this team has done into four particular university investigations, three by universities in Japan and one by a university in the United States. And so, we have this really detailed look at whether these investigations are accurate and rigorous because there is a growing disquiet in the academic community that says actually, universities can’t police themselves on misconduct and that there has to be some improvement on this front.

Interviewer: Benjamin Thompson

And how does one go about then assessing the quality of a misconduct investigation?

Interviewee: Nisha Gaind

So, what these researchers did, and they are led by Andrew Grey who is at the University of Auckland in New Zealand, they assess these reports against a checklist that is designed to help universities make sure that their investigations are robust. But their analysis showed that they were, frankly, inadequate. They said that all of them were unacceptable in quality and rigour.

Interviewer: Benjamin Thompson

And presumably, the researchers hope that their research will help increase the rigour of future misconduct probes.

Interviewee: Nisha Gaind

Yes, they say that their mission here is really to improve the policing of misconduct and fraud, and they say that their study here demonstrates that, in fact, overall, a lot of university misconduct investigations are poorly conducted and opaque and they hope that sort of illuminating the quality of these investigations will help others take notice and to improve rigour and transparency in these probes.

Interviewer: Benjamin Thompson

Well, let’s move on to our second story today, Nisha, and well, it’s a bit of a pressing issue.

Interviewee: Nisha Gaind

Correct, this is a story all about pressure and how researchers are redefining what pressure means.

Interviewer: Benjamin Thompson

I mean a few months ago, the standards units of the kilogram, the kelvin, the ampere and the mole were redefined. Is pressure the next one up on the list then?

Interviewee: Nisha Gaind

Well, yes, so metrologists are now looking to redefine pressure. The difference between pressure and the units you just mentioned is that pressure is what they call a derived unit, compared with those units which are base units – they are the most fundamental units of measure. So, the process here works in a slightly different way but, in essence, metrologists are trying to redefine the pascal and a lot of that focuses on the way that the pascal is measured in its most fundamental way, and that involves updating mercury-based methods that date back nearly 400 years.

Interviewer: Benjamin Thompson

Well, I’m going to show off here and say that the thing used to measure pressure is a manometer. How is the manometer being updated?

Interviewee: Nisha Gaind

So, some researchers in the US at the National Institute of Standards and Technology, they hope that the manometer, in a few years, will be obsolete because they have developed a new device that does what the manometer does but does it better, and it’s called a fixed-length optical cavity or FLOC.

Interviewer: Benjamin Thompson

And pray tell, how does the FLOC work?

Interviewee: Nisha Gaind

So, the main thing to understand here is that these researchers are trying to propose a different definition of the pascal to the one that is generally accepted. I’m sure it will be familiar to loads of listeners that the pascal or pressure is defined as force per unit area but instead, they propose that it can be defined as energy density, and the FLOC uses this principle to measure or realise the pascal. Now, rather than being mercury-based which is what manometers are, the FLOC uses lasers to probe atoms in a confined space, and from that it works out their density, and from that using a fundamental constant of nature, researchers can then derive pressure.

Interviewer: Benjamin Thompson

Well, what are the advantages then of this new way of doing things?

Interviewee: Nisha Gaind

So, there are a couple of advantages, and one is this concept that I just mentioned – that the unit will now be linked to a fundamental constant of nature. Now, that’s important because it means that the measurement doesn’t rely on other units, and that in turn means that anybody with the right equipment could derive their own pascal or derive the value of the pascal without having to do lots of tedious calibration measurements to other manometers which is what happens at the moment.

Interviewer: Benjamin Thompson

So, no maybe obvious downsides then – when can we expect this to be rolled out?

Interviewee: Nisha Gaind

This, amazingly, is the most complicated part of the story because there are some processes that these metrologists now have to go through to get their definition and to get their method, this FLOC, to become the accepted standard of the way that pressure and the pascal are derived. At the moment, the method works best for low and atmospheric pressures and these folks are currently adapting it for high pressures and then they have to convince the community and some measurement committees that their method is indeed as accurate as the old manometer, so there is a little bit more work to do and it is likely to take years.

Interviewer: Benjamin Thompson

So, maybe the pressure is off for a little bit, but Nisha, thank you so much for joining me and listeners, as always, head over to nature.com/news for more on these stories.

Host: Shamini Bundell

That’s all for this week, but if you’re not quite scienced out just yet, there’s a new video on our YouTube channel you can check out. It’s all about the immune system’s battle with HIV, and you can find it at youtube.com/NatureVideoChannel. I’m Shamini Bundell.

Host: Benjamin Thompson

And I’m Benjamin Thompson. See you next time.