Episode 56 - John Stinchcombe

Evolution, Adaptation, and Resilience of Plants in the Anthropocene

Theme: The Anthropocene

Published: 5 April 2024

Summary
This SCAS Talks episode features John Stinchcombe, a distinguished professor of ecological genetics, discussing plant evolution and adaptation within the context of the Anthropocene. Stinchcombe highlights the impact of climate change and intensive agriculture on plant populations, focusing on the evolution of herbicide resistance in weeds. He emphasizes the importance of studying these changes to inform agricultural practices. The conversation also touches upon the role of genetic engineering in enhancing plant resilience and the challenges of communicating scientific findings effectively to the public. Stinchcombe shares insights from his fieldwork in Peru and his experience fostering interdisciplinary collaboration at SCAS.

Keywords
Climate change, agriculture, herbicide resistance, genetic engineering, anthropocene

Suggested Link/s
Personal website: http://stinchcombe.eeb.utoronto.ca/?page_id=143 External link, opens in new window.

Transcript of the Episode

John Stinchcombe 00:10
Our current students have heard about climate change in media, social media, you know, politicians, pop stars, actors and so on. I try, since, when we're teaching science students, to actually show them some of the evidence we have. Because I think in part, many people have heard so much about climate change, but then actually haven't seen much of the evidence for it. And especially when something gets to become debated and become a political football that people are arguing over, it becomes pretty easy, I think sometimes for people to say, like, oh, climate change. You know, I've heard about that. But then I heard someone on TV saying it wasn't that big a deal. And I don't know, and it's easy to kind of like, wash your hands of it, and say, oh, this is some thing that everybody in society is fighting about. And instead, I try and say, okay, well, here are all the pieces of evidence. And even if you don't believe this one, do you believe the next piece? Do you believe the next one and then the next one? And then, if this is happening, we would make the following predictions, and here's evidence for those predictions.

Natalie von der Lehr 01:21
Welcome to SCAS Talks, a podcast by the Swedish Collegium for Advanced Study. My name is Natalie von der Lehr, and in this episode, I talk to John Stinchcombe, Distinguished Professor of Ecological Genetics at the University of Toronto in Canada. He was a fellow at SCAS within the Natural Sciences Program during the fall of 2023. We met in the lunchroom of SCAS one day prior to his departure, and discovered that his research about plant ecological genetics would be a perfect fit for the third episode in our theme "The Anthropocene". So why not use this opportunity and record an episode. We went straight into the studio and hit the record button. Welcome to the studio, John. And thank you very much for this very spontaneous interview. I usually prepare a small introduction of the guest, but since I haven't had time to do that really this time, could you please introduce yourself to our listeners?

John Stinchcombe 02:27
Sure. My name is John Stinchcombe. I am an evolutionary biologist, ecological geneticist, and I hold a faculty position at the University of Toronto in the Department of Ecology and Evolutionary Biology. And I've been a natural sciences fellow here at SCAS since September 2023 and I'm just about to head home.

Natalie von der Lehr 02:47
Can you tell us a little bit more about your research? What do you do there?

John Stinchcombe 02:52
Well, work that I've done and that my students have done is really focused on two things. The first is, we're super interested in natural selection, both measuring it in contemporary populations, in contemporary settings, in the field, in the laboratory or in the greenhouse, and understanding the sort of the ecological drivers of what is causing natural selection. And we work on plants, mainly because they sit still. They're really easy to work with as experimental subjects. And then the second portion of our work is genetic work, and that can range from everything from Mendelian genetics, you know, the flower color of peas, coat color of Labrador Retrievers, flower color incarnations, the genetics we all learned in high school all the way up to modern day genomics. And our interest in this is to understand, first, how evolution might be either facilitated or constrained by genetic factors, and then second, to look for signals of past natural selection in patterns of genetic variation we see in plant populations.

Natalie von der Lehr 03:58
How come you got interested in this subject?

John Stinchcombe 04:00
I started out actually as a bachelor of arts student as an undergrad, while very interested in biology, but I was unsure whether I wanted to do biology or law school or sort of environmental science. I was very interested in the environment, and as I took more biology courses and it got closer to ecology and evolution, I found I liked them better. And then I had a chance to do a lot of field work as an undergrad, the idea of sort of blending what we were learning about in the classroom to what you would see outdoors, either on an excursion or a longer trip, but also on my own, when I would go hiking or canoeing or go to parks with my parents and siblings and so on, I found that a very sort of seductive thing of both doing science outside and being able to use the science I had learned to understand what I was seeing outside. I would say that combination probably sent me down the path into science.

Natalie von der Lehr 05:00
Now this podcast episode is an episode within our theme "The Anthropocene". What is your definition of this term? Or do you have any thoughts on on this term and how it's used?

John Stinchcombe 05:11
I think of it as sort of the term applied to the geologic era where humans are some of the driving forces of not just the climate, but also sort of the atmospheric and oceanic chemistry, biodiversity and its loss on all the different continents at different rates and so on. Where it's a market change from past geologic eras where primarily natural causes were governing the height of the oceans and the size of the ice caps and the chemistry of the oceans and so on, or the composition of the atmosphere in terms of carbon dioxide and methane, those were previously natural causes. And in this case, there's clearly an anthropogenic signal, and it's having wide ranging repercussions on plants, animals, insects, you know, viruses, bacteria, just the whole tree of life, and also the chemistry of the atmosphere and the ocean and so on. But I'm a biologist, not a atmospheric scientist.

Natalie von der Lehr 06:10
But talking about biodiversity there. Do you have any examples from your own research that applies to that?

John Stinchcombe 06:17
Some. So there's sort of two real areas where we've worked on this in the set. First, modern agriculture is heavily reliant on, at least in the USA, Canada, Western Europe and a lot of parts of the developed world and high energy use societies. Modern agriculture in those areas is heavily dependent on fossil fuels and on fertilizers, irrigation, mechanical cultivation, herbicides, insecticides and so on. And so that we put a huge amount of nutrients or energy subsidy into our agricultural fields. And this works in the sense that yields and yields per area have gone up tremendously in the last 60, 70 years. Like this is one of humanities and applied sciences, sort of stunning achievements of how much more food that we get than we used to for a given unit of land. So there are good sides to it. The downside is that reliance on pesticides or herbicides, eventually means that the weed populations that are being targeted are going to evolve resistance. And so some of the work that I've done with a former graduate student, Julia Kreiner, and my colleague at the University of Toronto, Steven Wright, the three of us work together with colleagues, also in Canada, Germany and around the world, tracking the evolution of herbicide resistance and problematic weeds and the genetic mechanisms behind it, and how quickly it arose, and whether it arose once or multiple times, and so on. And so in the sense that energy subsidized and intensive agriculture is definitely a modification of the natural landscape, but it's a dramatic change from how humans have done agriculture for the previous, you know, 10,000 years. And this is having evolutionary consequences on pest populations, insect populations, weed populations and so on. We've done some work on that.

Natalie von der Lehr 08:13
But what can you do about that, then? When the weed this resistant to the pesticides and herbicides and so on?

John Stinchcombe 08:20
Well, in this case, knowing something about the genetics of how weeds become resistant and where it happens can actually inform what we might do. So I can give you sort of two scenarios. One scenario might be that weeds become resistant to herbicide in one location, and then that spreads to different locations, much the way Covid did amongst humans. And another scenario is the humans are spraying so much herbicide across the landscape that resistance is popping up independently in several different locations at once. Knowing the difference between these two scenarios would suggest alternatives about how we might do agricultural practices. So if it's originating in one location and then spreading, then we should be really careful about sharing a farm equipment, cleaning a farm equipment as it moves between locations and so on, because we don't want to bring herbicide resistant seeds of weeds, you know, stuck in the tractor tires or on the edge of the plow from one location to another. If it's arising independently in multiple locations, then that suggests we don't have to worry as much about sharing of the equipment. But instead, need to think about what herbicides we use, when we use them, other strategies that we might use, including, you know, crop rotation, some people suggest also sacrificing some portions of the field, of not spraying the entire field so that non resistant weeds can sort of remain and contribute to the weed gene pool. But it sort of sends you down a different path of what you might do to respond to the scenario.

Natalie von der Lehr 10:00
So in terms of climate change, anthropocene, where does your research come in there, do you think?

John Stinchcombe 10:06
So one of the other areas of my research is on trying to understand the ecology and genetics of when plants begin to flower. We work mainly in annual plants. They only live one year, and the timing of when they begin to flower is really important for their reproductive success, because if you wait too long and a drought hits, you might die with no reproduction. Maybe if you flower too soon and haven't grown to a sufficient size, you won't have enough resources to produce lots of fruits and seeds, or maybe produce really big, showy flowers to attract pollinators and so on. And so this is a really important trait in plant populations, and it's exquisitely timed in many plant populations to weather and to climate. And winters are getting shorter in most of the northern hemisphere, you know, snow free days are being reduced, or mixtures of rain and snow in the spring and more ice events and frost events are becoming more common. So the climate is changing dramatically. And so some of our work has looked at trying to unravel how quickly plants evolve in response to climate, some of the genetic basis of that, and work out what we might predict given this changing seasonality. Insects and mammals and birds and so on are also experiencing it. But the timing of when plants begin to flower is really become a model for understanding this.

Natalie von der Lehr 11:32
And how can you measure, can you measure the selection pressure on plants there, and how climate change or how the changing of the seasons influences them?

John Stinchcombe 11:45
Measuring selection on when plants begin to reproduce, it's straightforward, but it's labor intensive. In the last 40 years, there's been a well developed set of statistical and mathematical techniques for understanding natural selection in real time in the span of a single generation in a single population. And this is sort of within the standard toolkit of a lot of evolutionary biologists by now. So that part is straightforward. Linking it to changes in the climate you have to do sort of one of two things. One is to study the same population year after year after year and see if, you know, for example, if spring is coming sooner, consistently, and if that affects selection in each year. And there's been some, some very, very good work done doing just this, actually performed in Sweden, some in Uppsala by Jon Ågren’s group, and some at Stockholm by Johan Ehrlén’s group. That's one approach, and people have been have been doing that. The second approach is often that humans accidentally move plants around, and when they get moved to a new location, a lot of times, they evolve very quickly to match the conditions of their new location, and so that has been the the approach my group's taken is - we've worked on some mustards, which are native to Europe, the Balkans in North Africa, that were introduced to eastern North America in the last 200 years and have proliferated and diverged after that.

Natalie von der Lehr 13:23
But humans also move plants around intentionally because they want to grow something.

John Stinchcombe 13:27
Yes, for sure, they do intentionally. This, this is a very nondescript little mustard that, unless you're a botanist, would probably not be super interesting. So it's not like corn, rice, other agricultural crops humans move everywhere, and those crops also evolve in response to the climates where humans move them to.

Natalie von der Lehr 13:46
Yeah, we had, we have had episodes both about corn and also about potatoes. You also teach a lot?

John Stinchcombe 14:03
Yes, I do. I've taught first year biology, which sometimes will be a course of 2000 to 2200 students, and I've taught that on and off since I started at University of Toronto. But I've also taught second year of biology pretty extensively, since I don't know, 2012, 2013 and that's a smaller course of only 1300 students. And then, with one of my other colleagues at the University of Toronto, I co-teach a tropical ecology and evolution course where we take undergraduates to Peru for two weeks to do field work in both the Andes and in the Amazon rainforest.

Natalie von der Lehr 14:44
That sounds very nice.

John Stinchcombe 14:45
It is. It's an amazing experience. And you know, within the span of not that huge geographic distance, it will be cool in the Andes, too cold at night. And then you get down into the lowlands. And it's in the it's in the high 30s and super humid every day, and we haven't traversed very much geographic distance. But of course, the altitude has changed dramatically.

Natalie von der Lehr 15:11
What kind of changes can you see there in the plant populations and growth and so on?

John Stinchcombe 15:17
You see really dramatic turnovers of the entire composition of the communities, especially in the tropics, elevational gradients are really important contributors to changes in the diversity of what species you see, how many you see, where they're found, their density and so on. If you drive from high elevation in the Andes down into the lowlands. It's visible out of the car that you can see out the window the changing structure of the forests. It's pretty remarkable.

Natalie von der Lehr 15:49
But back to teaching then. I guess that climate change is a topic nowadays on the courses?

John Stinchcombe 15:55
Indeed. So my second year biology class, my section of it is sort of applied topics in ecology and evolution for humans, and we talk about things like the demography of harvested species. So for instance, in fisheries, human population growth, human adaptation to our foodstuffs and so on. And a big section of this, as you can imagine, would be climate change. And so it's gone from when I was an undergrad to something we kind of we knew was coming to now, something that I have several lectures worth of material on climate change and on the physical evidence for climate change, the independent pieces of evidence for it, the biological response of communities to climate change, the evolutionary response of communities to climate change. It's a pressing issue. And also scientifically, it's not under debate. There's heaps and heaps and heaps of evidence for it. And we can have, we can have a conversation about what we should do about it, how we should change society and our energy production systems and agriculture and so on. And there are a lot of different opinions about that, but the actual facts that we've been putting CO2 and methane into the atmosphere, and the climate is warming, and there's a coherent signal of this, is just undisputable.

Natalie von der Lehr 17:15
So what kind of input do you get from your students there on this topic? How do they react and what are their thoughts?

John Stinchcombe 17:23
Our current students have heard about climate change in media, social media, you know, politicians, pop stars, actors and so on. I try, since when we're teaching science students, to actually show them some of the evidence we have and measures of temperature, measures of temperature changing over time. You know how much nighttime temperature is changing relative to daytime temperature, whether glaciers are expanding or retreating, and whether lakes are thawing earlier later in the spring than they used to try and describe for them, all of the physical pieces of evidence we have that are independent measures. It's not just people with thermometers all over the world. Because I think in part, many people have heard so much about climate change, but then actually haven't seen much of the evidence for it, and especially when something gets to become debated and become a political football that people are arguing over. It becomes pretty easy, I think, sometimes for people to say, like, oh, climate change. You know, I've heard about that, but then I heard someone on TV saying it wasn't that big a deal. And I don't know, and it's easy to kind of like, wash your hands of it, and say, oh, this is some thing that everybody in society is fighting about. And instead, I try and say, okay, well, here are all the pieces of evidence. And even if you don't believe this one, do you believe the next piece? Do you believe the next one and then the next one? And then, if this is happening, we would make the following predictions, and here's evidence for those predictions. So for instance, in the evolutionary response to climate change, we have evidence from some species and not from others. And that's, that's the way science goes. You know, we might expect more in fruit flies and short lived things than we would in, you know, redwoods and things that have really long generation times. That's one piece of evidence. And if, even if you say, okay, I'm not convinced by that, what do you do about all of the other pieces? How many excuses do you have to come up with for why all of them, independently, are not pointed in the same direction? And I think at least outwardly, students are convinced they might also though be equally frustrated the lack of progress meaningfully addressing the issue?

Natalie von der Lehr 19:42
Yes, because that's the next step, right? I mean, number one is to understand that something is happening and seeing the evidence, and you present it to the students, but then what do you do with it? How should we react to this, and what can actually be done? You talked about the frustration that so little is happening.

John Stinchcombe 19:59
So this is a challenging topic, and some of this, also of what we can do, blends into engineering rather than, you know, biology or political science. I would think one component of it is going to have to be a move away from fossil fuel based energy sources. If we keep using fossil fuels and we keep burning them, we're just putting more carbon dioxide in the atmosphere. So one option would be to say, well, we like fossil fuels. It keeps our house warm and makes our cars run and our motorcycles fast and the lawnmower runs easy. We enjoy this, and we'll, we'll live with the trade off that the future world has to offer. I find very few people are willing to make that trade off explicit. People are willing to take the comfort of what fossil fuels provides us, but then pretend that the consequences of it are not going to happen. So if we're going to move away from fossil fuels as a source of energy, then there's a huge demand of energy, of what we're going to need to replace that, and while not my exactly my area, there's going to need to be a lot more solar power. My personal opinion is there's actually a room for nuclear power, that could be a key component of the solution. And I know nuclear power has a very different image and reputation in Scandinavia and in Europe than other places in the world. But, you know, it's, there's going to need to be just sort of everything. It's going to be solar, nuclear, you know, if you can get wind power without too much consequence, if you can get tidal power and use geothermal for heat, it's going to need to be kind of an all hands on deck approach to solving power in colder temperate climates, also solving heating.

Natalie von der Lehr 21:47
Yeah, it's a challenge. We had a special episode on solar power, actually in the spring, where the Nobel symposium was here with some of the world leading scientists. It was very interesting to see the enormous progress that has been made within the technology.

John Stinchcombe 22:03
There have been two huge changes to that, both in terms of the technology, but also the price. The price has dropped dramatically. So another major source of emissions in sort of high energy use societies is automobile and there are projections I read that the electric rechargeable car industry is going to take off in the next 20, 30, years and so on. I don't know for sure if that's true, but if true, that would also start to contribute a lot.

Natalie von der Lehr 22:34
What is your view on genetic engineering of plants to make them more resistant to, or more adaptable to climate change or insects or anything that can threaten them?

John Stinchcombe 22:48
I'm happy you asked this question, because, I'm strongly in favor of it, and I actually think that most of the resistance to it is kind of an emotional discomfort and is not actually grounded in science. I know emotions are important. People are afraid of things that are different and so on, but I'm hugely in favor of it, and I think actually there are a lot of advantages to them. And I also think that a lot of the people that push the disadvantages of it aren't really bearing the costs of that decision. So, for example, I know in Europe, the GMOs are much more strongly regulated in food, but the people who sort of suffer from that are the food producers, a lot of whom are outside of Europe. And so it becomes very nice to oppose using GMOs from one part of the world, while the consequences of that commercial standard are being felt elsewhere. I think the US and Canada are not quite like Europe in their opposition. But do you still also see in, you know, in trendy grocery stores or in the health food aisle the grocery store, a lot of stuff that's advertised to be GMO free.

Natalie von der Lehr 24:02
Even DNA free.

John Stinchcombe 24:03
Yeah, my favorite is to see a bottle of water marked as gluten free. GMOs involve manipulating individual genes of known function for a known purpose. Traditional breeding or alternatives to GMOs often involve, for instance, doing artificial selection in a way where we don't know anything about the genetics of what's changing, or doing hybridization, blending two separate crop species together and hoping for a beneficial variety or a beneficial component to emerge. Some people will target things by mutagenesis, trying to induce lots of mutations. And, you know, peas or beans or whatever they're working on, and then when they see a beneficial feature, then trying to breed that into their bean. And it doesn't make sense to me that something created by exposing plants to a mutagen to induce a mutation or a change in the genome of that target species. How that's really any different than something that has been engineered and selected for a purpose. And whenever it's been studied, there are no health consequences or nutritional consequences of GMO technology that we can detect, and people have looked pretty hard, because there's a group that is vehemently opposed to this, and also from the standpoint of the people growing the crops and working with the crops. So I mentioned that, you know, the the GMO free stuff, at least in North American grocery stores, is often found in the organic section or in the health food section, where people are concerned about the pesticides and insecticides and so on - which I am concerned about pesticides and insecticide use. But GMO crops sometimes allow the people who are actually working growing the crops actually to be using much less chemicals, and so we're spraying less out into the environment. It's less likely to hit non target organisms. The individual farm workers who are handling the chemicals and having to, you know, deploy them and mix them and so on, are also having much less exposure to it. And so I'm a strong proponent of GMOs.

Natalie von der Lehr 26:16
Do you get popular at parties with this opinion?

John Stinchcombe 26:18
I sometimes joke, if you know, people will bring, you know, you have a dinner party or something, and people bring stuff over to, you know, I don't know, prepare charcuterie or cheese and crackers or something, and they'll pull out a box of crackers that says, GMO free. I sometimes say this, no, this is a pro GMO house. We have a chuckle over that. At least for me, nuclear power and GMOs are things where I think a lot of scientists have a different set of views than you might typically expect, of, for instance, people who care a lot about the environment or conservation and so on, or global climate change, and that it's pretty common among scientists who have like, oh, I care a lot about conservation or preserving biodiversity or climate change and so on. It's much more common than among the scientists you meet who have those passions and interests for them to be pro GMO and pro nuclear, than if you meet someone who's not a scientist who has those same interests. You have to go and pack up your apartment. I do. I'm catching a flight tomorrow morning.

Natalie von der Lehr 27:28
So just a round off, how has your time been in this multi- and interdisciplinary research environment?

John Stinchcombe 27:35
It's been very interesting. So there are not many natural science fellows at SCAS. SCAS is mainly focused on the humanities and social sciences, though there is a natural sciences program, and it's super interesting in the context of seminars, lunches, etc, because you know, you'll be sitting and having a conversation with someone who's a specialist in literature and someone else who's an ancient Greek archeologist and someone's an economic historian and a linguist and a sociologist and so on. So that's been, it's been very educational. I've had, on and off, some exposure to the humanities and social sciences through academic life and colleagues and friends and so on. But this has been a little bit of an immersion in that. And on the whole, I've really enjoyed it.

Natalie von der Lehr 28:24
Great. We hope to see you back here.

John Stinchcombe 28:26
I hope to come back. I think it is - so we just chatted for a lot about the interaction of science and society as it relates to climate change, as it relates to GMOs. For scientists to be able to have conversations with experts outside their area is a key component of at least removing the scientific uncertainty or the scientific ignorance or the scientific misconceptions about these topics, and then you know what we should do as society. You know it sort of enters the realm of politics and ethics, but I do think it is useful for scientists to sort of both get practice at communicating outside their discipline, but also to see how science is understood by non scientists.

Natalie von der Lehr 29:16
Thank you very much for this very spontaneous on the spot interview.

John Stinchcombe 29:20
No problem. Thank you. This was fun.

Natalie von der Lehr 29:26
And thank you for listening to SCAS Talks, a podcast by the Swedish Collegium for Advanced Study. In this episode, I've talked to John Stinchcombe, Distinguished Professor of Ecological Genetics at the University of Toronto in Canada, and fellow at SCAS within the natural sciences program during the fall of 2023. And this was the third episode in our theme "The Anthropocene". And we have talked about his research on plant evolution, climate change and the potential of genetically engineered plants. In the previous episodes within this theme, we have heard Gíslí Pálsson, professor emeritus in Anthropology at the University of Iceland, about the discovery of extinction, and Aaron Allison, Senior Research Fellow Emeritus in Ecology at Harvard University, about decentering ourselves from the Anthropocene. And these are episodes 48 and 50 respectively. If you're interested in solar energy, you might also want to listen to our special episode SCAS Talks Spotlight on the Nobel Symposium NS 191 "Efficient light to electric power conversion for a renewable energy future". And in episode 32, Karsten Paerregard, professor emeritus of social anthropology at the University of Gothenburg, took us to the Andes and told us more about climate change, climate perception and water management in Peru. SCAS Talks features a broad variety of topics, which is a reflection of the multi and interdisciplinary research environment at the collegium. We are sure that there is something of interest for everyone. Tune in, find your favorite topic or surprise yourself with something new. And as always, we are very happy if you can recommend SCAS Talks to your colleagues and friends. Subscribe to us and you won't miss any new content. SCAS Talks is available on podbean, Apple podcast, Spotify and most podcast apps. I would like to thank John Stinchcombe once again for talking to me, and thanks to you for listening. Bye for now!

Transcribed by https://otter.ai