Simulated winter warming negatively impacts survival of Antarctica’s only endemic insect: Podcast Transcript

In this podcast for Functional Ecology, Assistant Editor, Frank Harris, sits down with Jack J. Devlin—an early career researcher from the University of Kentucky—to discuss his recently published paper ‘Simulated winter warming negatively impacts survival of Antarctica’s only endemic insect.’ With warmer winters expected to become more common with climate change, this study’s results indicate that winter warming could negatively impact cold-adapted insects like the Antarctic midge (Belgica antarctica). At the time of writing, this research is “in the top 5% of all research outputs ever tracked by Altmetric”.

Listen to the podcast by clicking here!

Frank:  You have just been listening to an Antarctic summer soundscape. This was recorded by Dr. Nicholas Teets—a co-author on the paper which is the subject of this podcast today. Today, I have Jack Devlin with me. He is the lead author of a paper entitled ‘Simulated winter warming negatively impacts survival of Antarctica’s only endemic insect.’ Before we get into the paper, I’d just like to ask Jack to tell us a little bit about himself and his research interests.

Jack: Thank you for that. I’m Jack Devlin and I am from rural mid-Wales. PhD-wise, I call Kentucky, USA my home and I would describe myself as a general-interest ecologist. I did my Master’s with a focus on entomology, looking at how pheasants might impact insects in the rural Welsh landscape. Funnily enough, I moved into Antarctic invertebrates through Twitter! I was mindlessly scrolling one day when my master’s was drawing to an end, and up popped a tweet from a certain Dr. Nicholas Teets. The tweet asked “do you want to do fieldwork in Antarctica? Are you interested in the ecophysiology of Antarctica’s only endemic insect?” I thought to myself ‘yeah I am, the first bit especially’! This led me to apply and interview. I had the interview after I had just returned from the Azores where I was working on a seabird project on a tiny remote island with two other people for one month! When I was back into ‘normal life’, I decided that I was definitely going to go for this opportunity and, as they say, the rest is history!

This is my third year of my PhD, so I am getting to the stage where things are starting to come together and I begin to publish different works. This article today is my first chapter and it has been very well received and I am very happy about it. It was really quite a challenging paper for a multitude of reasons—not least the COVID-19 pandemic. I was incredibly lucky because, although I didn’t go to Antarctica in 2020, we had a dedicated field team out there collecting for a number of different studies including mine. Following this, the pandemic hit and the team effectively had to run away as quickly as possible and catch the last flight back from Chile to the USA. I was incredibly lucky to even have any midges to work on; however, to make matters worse, the university had to then shut down. I needed to get special permission to start this experiment and then I effectively wasn’t allowed to check up on it for a while until the pandemic had calmed. That made the study very difficult, but I am still very pleased with how it turned out.

Frank: Perfect. So, if you can excuse the pun, in an ecological sense you are a ‘Jack of all trades’! What kind of advice might you have for other budding ecologists? You are a young early career researcher, so what tips can you provide to keep people interested and focussed on completing their studies?

Jack: For a start, do what you are interested in! There is a tendency for a lot of young researchers to be not so much told, but guided toward things that they are not necessarily so interested. I’m incredibly lucky that my supervisor, Dr. Nick Teets, has been incredibly flexible in letting me do what explore my own interests. It’s important to mention that this study was a big risk. Putting things together and then not looking at them for 6 months is a big risk if it all goes wrong. But I would say that to sum that up, have the best supervisor you can find! Take your time to find someone who is not just a supervisor, but is a mentor that will actually let you have that freedom, but can also provide support. When it comes to writing a thesis—I’m not quite at the horrible stage yet—I would say just try and do a little bit every day. Try and do a little bit of writing, or make a figure here and there. If you keep it ticking over it won’t build up into something horrible. Saying this, ask me again in a year and I might give you a different answer!

Frank: You grew up in mid-Wales, with the Brecon Beacons right on your doorstep. Was that a gateway into ecology for you?

Jack: Yes, that’s a really good point. I studied in Cardiff University for both my Undergraduate and Master’s. Whilst there, I was very lucky to meet very passionate ecologists—one of them also grew up around this area! For me, becoming an ecologist was really just about trying to get myself to stand out. I was lucky enough to do fieldwork on seabirds in Portugal for two years of my Undergraduate. Becoming an ecologist was about just getting out there and making myself known (whilst backing it up with good grades). To answer your other question, I’ve always been interested in nature. I’m incredibly lucky that my parents live in super rural mid-Wales. You can go outside and see some rare animals, and, being a kid, I was always down at the pond without any concern for the weather. To come full circle and be able to do this as a job is somewhat of a dream.

Frank: I’ll ask about the paper now. You were investigating simulated warming effects on the Antarctic midge (Belgica antarctia). Can you tell us, in plain terms, about the novelty of your paper? What does the study contribute to the understanding of the impact of warming on Antarctica’s only endemic insect?

Jack: The study is novel because it is the only study that has tried to do a simulated overwintering period for this insect. For Belgica specifically, the longest previous overwintering period we looked at was around 32 days. But we found that even at -5°c, the larvae were surviving completely fine! Now we know that the Antarctic winter is changing, with climate change definitely occurring in the region. Belgica, to give you context, is distributed along the northerly peninsula of the Antarctic where conditions are ‘more mild’. We know that Antarctica is warming during the winters, we know that it’s approximately 0.5 degrees centigrade per decade since 1950. But, that might not mean that everything is just going to get warmer every single year. There is of course going to be variability in each winter.

In this study, we really wanted to investigate what the temperatures of Antarctic winters are to begin with, and then, the study would develop around a sort of mean (-3°c), then a very warm winter (-1°c), and finally a colder winter at (-5°c). We really just wanted to look at a full 6 month investigation into how the larvae would survive. It was a really big unknown—we know in the field that they can tolerate variability, but we don’t know precise information regarding what temperatures they are tolerating. This was the most straightforward method, based on the equipment we had, to be able to investigate this.

Frank: I’d like to ask about the Antarctic midge. What is it about its physiology, or more how has it adapted to survive in such a hostile environment?

Jack: We know that the Antarctic midge has been in Antarctica for a good few million years, and it’s been separated from its closest living South American relative for over 50 million years. We know that it’s a highly adapted and endemic species in what is arguably the most challenging environment on earth for an insect to live on. It is easy enough to just think Antarctica must be very cold, but we need to think about the fact that although there are going to be colder temperatures, we can also have a lot of UV radiation, incredibly strong winds, and risk of drying out—a severe risk for any insect living in Antarctica or a cold environment. We’ve also got things like salinity—in the storms we can have larvae being submerged in saltwater pools. It’s really not the easiest environment to live in for any animal; but the Antarctic midge really has adapted over time. If we think about the cold temperatures, we know that the larvae take around 2 years to reach adulthood, which for something that small is a ridiculous amount of time. If we compare it to temperate-living midges, they can do a generation in a summer quite easily. For the Antarctic midge, they need to go through 2 winters before emerging as an adult. You might think all this time indicate that they will go on to live long lives; however, unfortunately, they emerge and live 10 days without eating; they breed, and then there’s a mass die-off.

It’s an incredibly challenging environment, but these animals have been highly adapted to it. For anyone who is interested, I would recommend reading the work that my supervisor, Dr. Nicholas Teets, has done along with another great physiologist, Yuta Kawarasaki. Those two really did some fantastic work, now and a few years ago, looking at the ecophysiology of the Antarctic midge. We know that they are incredibly tough animals that can tolerate a lot more than temperate midges.

Frank: So in this study, you measured a range of physiological outcomes: survival, movement ability, damage to organs, etc. Can you discuss a few takeaway results—things that might have surprised you or were expected? What are some key outcomes of this study?  

Jack: We found that warmer winters (-1°c) resulted in survival, energy stores, locomotor activity (movement/speed) all being significantly lower. There might be this idea of energy drain. Additionally, not only will animals die before the winters are through—those that are surviving are going to be more sluggish, and they might not have ability to move as quickly to a food source. To add to that, we used late-instar larvae that are going to pupate after they’ve emerged from the winter. We know that they have limited time before they are able to pupate, so there might be few feeding opportunities anyway. Therefore, if you are emerging out of a 6-month winter with lower protein and lipid stores, then you are going to have less of a chance to successfully pupate and emerge as an adult. Let’s say you are able to emerge as an adult, if you have lower protein stores, particularly, then your reproductive output might actually be lower. That has implications for not only the animals that go through the winter, but also the generation after that.

These were sort of expected results to be honest. We know that if you put an animal, that hasn’t got a chance to move around and eat, into higher temperatures, it is going to have to use those energy stores. However, one result we had that was very out of the blue, was to the extent at which larvae did not like being overwintered on the Prasiola crispa algae. For a bit of context, this algae is EVERYWHERE in low-lying regions of peninsula Antarctica. We know that it is a fantastic food source for the midge. In fieldwork, you can go and see massive amounts of this algae spread across rocks, and if you lift a rock up, you can almost guarantee that there will be midges. However, we did not expect for the midges to survive so poorly on this algae. For midges that went through the warmer winter (-1°c) and were overwintered on this algae, none survived. We did not expect that at all, and we’re not even sure why they did so poorly. We know that this algae can release what is called phytosterols which are toxic to Drosophila melanogaster (the fruit fly); however, we know that Belgica eats it all the time in the field. Perhaps being in close contact and not being able to move away when the algae releases these harmful chemicals is the reason for the decline in survivability, but this is something we need to investigate. That was a very very unexpected result, that is for sure!

Frank: That’s amazing. I don’t want to steal thunder from your thesis and future work, but now that you’ve completed this study, where do you hope to be moving towards? What’s the next step/goal, and where do you want the general field to open towards?

Jack: Well, in a lot of cases with papers (like this one) that try to answer big questions, you end up just asking more questions. In this case, one point that we tried to clearly make in the paper is that “yes, these are the results we have seen after 6 months,” but a warmer winter might actually reduce the duration of winter itself. Or indeed, a warmer winter may cause harsher conditions for the shoulder seasons (before/after the winter), so we really don’t want this to be definitively negative—I.E., it’s warmer, so it must be worse for these midges, oh no, they’re going to go extinct! We want to show that this opens up more questions, particularly looking at temperature variability. We must try to determine whether it is the length of winter, the temperate of winter, or the degree to which the temperature varies that are the driving forces behind Belgica’s survival. We know that these midges are found in a wide variety of different microhabitats. They are distributed across a 600 mile range, so it’s not going to be the case that every midge is experiencing between -1°c to -5°c for 6 months. We know that there is a lot more variability; however, we can definitely now start to hone in on the minutiae around what is driving these results. Unfortunately, for my thesis, I won’t be working on that. I am interested in looking at summer conditions from a transcript abundance response angle.

I talked before about how these midges can be exposed to lots of different stresses. I’m going to look at how they respond to sub-lethal stresses of temperature, salinity, or desiccation… that kind of thing. In my other chapter, I’m going to be looking at whether we can detect microplastic within Antarctic midges, and also whether we can detect a physiological response from exposure to microplastics at levels we might commonly see in the field. That’s all reliant on me actually getting to Antarctica, which I’m hoping to do next year—fingers, toes, and everything else crossed that I might have something to update you with in a year or so.

Frank: Fingers, toes, and everything else will be very cold when you do eventually get down there. I’m going to ask you to get your magic ball out—probably the least favourite thing for a scientist to have to do. I want to ask what the future, based on data we know and that you’ve collected, looks like for invertebrates or other organisms in Antarctica—can you describe different visions of the future? Furthermore, can you touch on whether there are any impacts from the Antarctic midge declining in species number? Do they have natural predators? Is there a threat of an ecosystem chain collapse if we were to lose the Antarctic midge?

Jack: If I work backwards from that, we know that Belgica can be incredibly numerous—we can find about 40,000 per square meter in Antarctica! But, we can also go a few meters and find none. It’s a very patchy distribution but there are a lot of them. At present, we haven’t found any natural predators, especially of the larger larvae. They might be eaten when they have just hatched, but as far as I know we haven’t found anything concrete. They are incredibly numerous and, interestingly, the largest animal to live in Antarctica all year round. At 5 mm and 1 milligram in weight, that’s very small! However, if you combine that with their biology, they are a generalist detritivore—in simple terms, anything that is rotting… dead animals or dead organic material are going to be incredibly important for nutrient cycling. In Antarctica it is a very simple ecosystem which is only represented by a few dozen (up to a hundred) species of invertebrates in total. So if we are looking at the importance of Belgica, it is the largest and it is very numerous. Does it have an impact on nutrient cycling that we can measure? Yes, very likely. We haven’t done that yet to my knowledge, but if there were to be a contraction in population size due to lets say winter warming, then you should be able to see a decrease in nutrient cycling in Antarctica. What the future looks like for these animals and the community in general is… well… very unsure.

You could be forgiven for reading my paper and thinking “well it’s getting warmer, it must be bad and leading to extinction.” That probably isn’t the case. These are animals that are very highly adapted to cold conditions; however, we know, particularly for lots of animals, that they can tolerate higher temperatures. So as I said before, if we’ve got these reduced length winters that are warmer, then the midges might be able to cope and go through a selection event for the midges that CAN survive warmer and reduced length winters. We might then see more flexibility. However, on the other hand, If it continues to warm to this degree, we will see an increased risk of invasive species colonisation which can have impacts for the ecosystem. You’ve got incredibly highly adapted animals that have been there for millions of years, to then have to contend with invasive species that get there naturally (or anthropogenically) can have implications, especially if they are able to survive a less harsh Antarctic winter. We are still at the very early stages of determining invasion risk, and how invertebrates will deal with climate change as a whole. This is my scientist’s way of looking at things where I don’t actually commit to saying anything!

Frank: Thank you. Just to finish up, I would like to let the listeners know that a link to the paper is available in the description of this podcast. I would highly recommend checking out the paper. It’s attracting a lot of interest and being picked up by various news sources. It’s a fascinating paper and I am very grateful to Jack for taking the time to be here and discuss his research with me. Just as we finish up, I’d like to give Jack the opportunity to give a shout out to anyone who deserves it, and ask, do you have any take-home messages for the listeners—I.E., if this is the only thing you take away, you should know this!  

Jack: I’d like to thank every single one of my co-authors. To give more context around the COVID difficulties, I actually got stuck in the UK over the summer of 2020. I was unable to get back in time for my experiment finishing, so I was incredibly lucky to have PhD students, Laura Unfried and Eleanor A. McCabe, and post-doc, Melise C. Lecheta. They were able to actually get my experimental subjects out of the incubators and actually do the first initial analysis on survival and locomotion. I would not have been able to complete this study without them. This was also very much a team effort—it’s easy to look at the first author and think they did everything. This was completely a team effort and I couldn’t have done it without their support. I’m very thankful to the other co-authors— Josiah D. Gantz, Yuta Kawarasaki, Michael A. Elnitsky, Scott Hotaling, Andrew P. Michel, Peter Convey, Scott A. L. Hayward, Nicholas M. Teets. They have been absolutely brilliant in advising me, in guiding the paper with their expertise, and I am just so proud to have been able to collaborate with people with whom I’ve been reading their work for the last 2 years as an outsider. They are fantastic people to know, and hopefully I can put out a few more papers that can get a similar response because this has been a really fun experience.

Frank: I hope the listeners have enjoyed our discussion about your paper. Thank you very much for your time Jack. It’s been great chatting to you.

Jack: Thanks very much indeed.

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