Ep 106: Long-term experimental evolution in the wild (with Katie Peichel and Andrew Hendry)
Can we predict evolutionary outcomes if we know starting conditions? Do the products of evolution in nature differ from those studied in well-controlled lab experiments?
On this episode, we talk to Katie Peichel, head of the Division of Evolutionary Ecology at the University of Bern, Switzerland, and Andrew Hendry, professor in the Department of Biology at McGill University, Canada. Katie and Andrew are part of a massive research team working on the evolution of threespine sticklebacks as they are reintroduced into lakes in Alaska. Sticklebacks have been a favorite species for evolutionary biologists since almost the origins of modern evolutionary theory. Traits like spine size and lateral plate armor evolve rapidly when populations colonize new habitats, leading populations to barely resemble one another. Unlike traditional evolutionary experiments, which try to infer what occurred in the past, the Alaska project is tracking in unparalleled detail changes in the phenotypes and genotypes of fish that went into each lake population.
We talk to Katie and Andrew about the origins of this incredible project, the pros and cons of different approaches to studying evolution, and the need for long-term experimental studies of evolution in the wild. This is the first of a series of episodes we will be doing on the Alaskan research project, so stay tuned!
Cover photo: Keating Shahmehri
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Art Woods 0:08
In the popular imagination, evolution can't be seen directly because it unfolds over geologic periods of time.
Marty Martin 0:15
But we now know from decades of work that some species evolve really fast if circumstances are right.
Art Woods 0:21
Bacteria and viruses can evolve significantly in days or weeks. Fruit flies in months to years and some fast living birds in a year or two.
Marty Martin 0:28
Biologists have observed rapid evolution in three primary kinds of studies. The first are what are called laboratory natural selection experiments. In these you hold captive populations in the lab under a set of defined conditions and then observe how they evolve.
Art Woods 0:42
Here's a famous example. Rich Lenski at Michigan State University started a long term experiment on E. Coli in 1988. The design was ingeniously simple, he set up 12 replicate populations of bacteria in flasks in a bacteria friendly growth medium, and then transferred 1% of each flask to a fresh flask every day.
Marty Martin 1:01
E. coli grow and divide so rapidly that they go through six to seven bacterial generations in just one day.
Art Woods 1:07
So he had bacteria living in novel conditions in the lab-
Marty Martin 1:10
recall that their natural habitat is the GI tracts and on the fingers of small children at playgrounds.
Art Woods 1:15
-at high population sizes with multiple generations per day conditions right for evolution. And indeed, he and his team observed that they adapted fast, especially during initial generations, and they came to perform much better in the lab environment than did the founding population.
Marty Martin 1:28
A result that could be seen directly because they froze samples of each population every 75 days. They could later revive the samples and measure the relative performance directly and at the same time.
Art Woods 1:38
Amazingly, this experiment is still running after 35 years and the bacteria are still evolving.
Marty Martin 1:44
Here's an important thing about that E. coli experiment. Using laboratory natural selection, researchers don't select directly on traits by examining phenotypes and sorting winners from losers. Rather, they put populations into new experimental environments and let them go.
Art Woods 1:57
But one could also select directly in effect becoming "the hand." No, not the hand of Queen Daenerys, but the hand of natural selection.
Marty Martin 2:05
Which turns out to be the second main way that biologists study evolution experimentally.
Art Woods 2:10
An example,
Marty Martin 2:11
in 2001, George Gilchrist and Ray Huey, then both at the University of Washington measured the response to selection on so called knockdown temperature of fruit flies. Over 32 generations, the team selected flies for their ability to withstand progressively higher temperatures,
Art Woods 2:26
by fractionating them as they fell out of a progressively heated column. In some of the lines, they kept flies that fell out last, and thus were the most resistant to high temperatures. In other lines,
Marty Martin 2:36
the control lines,
Art Woods 2:37
they kept flies that fell out right around 37 degrees.
Marty Martin 2:41
At the end of this study that knockdown temperature in line selected for higher temperatures evolved to be much higher than those in the control lines.
Art Woods 2:47
Given the fruit flies have generation times of 10 to 12 days, they were able to run the whole experiment in just a little over a year.
Marty Martin 2:54
Okay, that's a lot of details on lab experiments. But of course, scientists also study evolution in the wild, which after all, is what we really want to understand. You can probably come up with some examples.
Art Woods 3:04
Of which one of the most famous is Peter and Rosemary Grant's work on Darwin's finches on the Galapagos Islands. We talked to Peter and Rosemary about their work way back in Episode 28.
Marty Martin 3:13
Geez, Art, were we even out of diapers then?
Art Woods 3:15
Over several decades of careful observations, they witnessed multiple evolutionary shifts in the size and shape of the beaks in Finch populations,
Marty Martin 3:23
And they get deduced that those shifts resulted from very strong selection on beak traits.
Art Woods 3:27
Beaks are the all purpose tools by which birds interact with their environments, and when environments change in ways that alter the foods that are available-
Marty Martin 3:34
think big droughts or big rains-
Art Woods 3:36
Selection on winning and losing beak traits can be super intense.
Marty Martin 3:39
Sometimes leading to measurable evolutionary change. Thus, this third approach to studying evolution is what we might call observational-- you study populations over long periods of time and observe how they change with potentially other studies to identify what selective factors are at work, and perhaps what genetic and developmental processes change in parallel.
Art Woods 3:58
What such observational studies typically don't do is to manipulate populations or conditions directly in the wild, and then follow evolutionary trajectories in detail.
Marty Martin 4:07
Which brings us to today's guests, Katie Peichel, who is head of the division of evolutionary ecology at the University of Bern in Switzerland, and Andrew Hendry, a professor in the Department of Biology at McGill University in Canada.
Art Woods 4:18
Katie and Andrew are members of a large interdisciplinary team working on a grand experiment that was recently set up in lakes in Alaska.
Marty Martin 4:25
A few years ago, the team introduced another favorite species of evolutionary biologists small fish called three spined sticklebacks into nine lakes in Southeast Alaska. The lakes had recently been rendered fishless, in order to get rid of another invasive species and Alaska Fish and Game worked with the team to reintroduce new populations of sticklebacks, which are native to the area and lived in the lakes historically.
Art Woods 4:48
This experimental introduction of fish gave the team an unparalleled opportunity to do a powerful long term evolutionary experiment in the wild.
Marty Martin 4:55
First, the introduced fish are from known source populations, and the starting traits and genomes of those fish are being analyzed in detail, so the team knows what the starting points are.
Art Woods 5:04
Could be really important for understanding evolutionary trajectories.
Marty Martin 5:07
Second, they're in the middle of following each population for multiple years measuring a whole suite of life history, morphological and physiological traits, and then trying to link that variation to evolve changes in the genome.
Art Woods 5:19
This is obviously not the first experimental evolution ever done in the wild.
Marty Martin 5:22
For example, recall all the great work that's been done on guppies in Trinidad, some of it by our own Cam Ghalambor.
Art Woods 5:28
But it's one of the grandest and most complete.
Marty Martin 5:30
In our chat today we discuss the pros and cons of different approaches to studying evolution in the wild and the need for large scale experimental studies.
Art Woods 5:37
This episode is the first of several that we'll produce on the team's work. So stay tuned for more next year that will focus on some of the early results.
Marty Martin 5:44
I'm Marty Martin.
Marty Martin 5:45
And I'm Art Woods.
Marty Martin 5:46
And this is Big Biology.
Art Woods 5:59
Katie and Andrew, thanks so much for joining us on Big Biology. Thrilled to have you here. We also want to just give you our congratulations on getting funding from multiple sources for this massive project that you're working on in Alaska now on experimental evolution of sticklebacks, and we're gonna dig into a lot of the details of stickleback's natural history, some of the traits that are evolving that you guys are interested in, and things like the genetic underpinnings of some of those traits. But we want to start with maybe a broader overview of just thinking about different ways that people, different groups, have studied evolution in the lab and in the wild. And what's unusual and hard about long term experimental evolution in the wild. So maybe just for context, can you tell us like, what are the main ways that people study evolution? That's not what you're doing?
Andrew Hendry 6:48
I mean, I feel like I have been writing a grant right now where I've been trying to sort of outline the contrast between what we're trying to do and what is the typical thing. So I feel like I almost wrote this out in advance.
Art Woods 6:48
Oh great.
Andrew Hendry 6:51
I'll keep it short, though, of course. I mean, basically, if you go back far enough, people would criticize evolutionary biology as a strictly historical science. Basically, that is, it's not something you can study through experiments, you have to go back and look at the existing patterns or dig up fossils and try and make inferences about what might have happened. It's not a field that's amenable to experiments. But maybe 20 years ago or so roughly give or take and little bit longer before that people realized that if you have organisms with short enough lifespans, that in fact, you can actually do experimental evolution, because you, you do laboratory experiments, and you take your microbes or your flies or whatever, and you put them in different environments, and you see how they evolve into the future. So it does become an experimental science. And I should point out that it's actually much longer than 20 years ago, because people were doing experimental evolution on Drosophila starting maybe 100 years ago. But the stuff that brings it more into a natural setting, which is what I want to mention next, that came only about 20 years ago. Now, the problem with these lab experiments is that in my view, and view of many, they don't really reflect the real world. If you're interested in the evolution of microbes in the in the hospital, well, then you want to do that kind of setting, but if you want to ask about how from a more ecological conservation type perspective, things are evolving in the quotes "real world," then you kind of got to do experiments in nature. And those are much harder.
Art Woods 8:32
And so the concern here is that if you do these experiments in the lab, you're controlling everything, you're imposing some particular environmental change, then you see an evolutionary response to that. That's awesome. Except that, you know, you don't have the fully complex environment. And the worry is that in that fully complex world, the evolutionary trajectories are different in some way than they would be in these highly artificial lab settings. Is that it?
Andrew Hendry 8:56
Yeah, I mean, it's like, I jokingly call such experiments with my colleagues who do these experiments that they're elegantly irrelevant, right? Because they're beautiful. They're, you know, they're controlled, they have tons of replication, everything is standardized. And so it's really elegant, but they're kind of irrelevant, because the world is never like that, right? You never have exactly equal experimental replicates. And so, you know, those are great for underlying, like doing an experiment to detect some particular underlying cause of something. And it's kind of like proof of principle. Yeah, if I do this thing, then this standard set of organisms, with the standard genotypes, they will respond in this way. But you don't know if that will actually happen out in a natural setting. And so that's what experiments in nature are hoping to do is to see what signals emerge when you have your experiment layered on top of natural complexity.
Art Woods 9:51
Just from a theoretical point of view, like what would be different when you have the full complexity of the environment, what do you envision as being a different evolutionary trajectory in the wild versus in the lab?
Katie Peichel 10:03
I mean, one important component is just this multivariate nature of selection in the lab, you know, you might be saying like, you're under low glucose conditions, right. But in the field, you've got different predators, different food resources, different abiotic conditions, and organisms are having to adapt to all of these different things at the same time. And that's what you're really I think, missing in the lab temporal fluctuations, for example, you don't really see that in the lab as well. So I think that's one super important component.
Andrew Hendry 10:37
So I'd say that's one angle, basically, is this idea that you never have an isolated selective force, right? Evolution doesn't work that way, the environment doesn't work that way. The additional complication I think is important is that you have a context to the action of selection, and that context will vary from place to place. So let's say you have it's warmer in one location and cold in another, it's got a different competitor in one location than in another location. And yet, you're trying to understand, for instance, what's the effect of predation? Well, the effect of predation might depend on whether it's warm or cold, or whether there's a competitor present or absent. And so the average effect of the predator, when you remove all of that other variation might not be relevant to any one specific instance in nature. And it might not be predictive of how different populations will respond to a new predator, because it depends on whether that population was in warm or cold conditions or with a, you know, another species that's a competitor or not, or parasite or whatever.
Art Woods 11:36
Yeah, yeah. There's a maybe this is sort of another piece in the same set of things that you're talking about. But one thing I've worried about a lot in my own work, which is on, you know, insect, ecophysiology is the roles of condition and disease in the wild versus in the lab. And, you know, often we use animals in the lab that are, you know, they may be unhealthy in other ways, like because of the diet they eat, but they're typically not plagued by lots of diseases like many of the wild individuals are. And it always just felt to me like, that's a really important missing component of sort of eco phys is to use animals that are compromised in various ways, because that's how animals in the wild really are existing much of the time. And you can imagine that really changing selection pressures and sort of what matters physiologically and morphologically in the wild if things were sick versus not sick. What do you think about that?
Katie Peichel 12:27
I mean, I think that's definitely true. And I mean, that's one cool thing about our project is we'll have Dan Bolnick studying all the sort of parasites that are infecting these fish and looking at immune function and things like that. I think that's a missing component, I think, in a lot of evolutionary biology is thinking about sort of the immune function and how that might be impacting adaptation to different environments.
Andrew Hendry 12:53
I mean, people try to assess these kinds of interactions by going out in nature and measuring every possible thing they can on natural populations across all kinds of environmental gradients. And they try to draw correlations between these things. But when you then try to test whether that's like some sort of causal effect, rather than just correlations that are occurring in nature that aren't cause and effect, then you need experiments. So bringing the two things together is what we're trying to do.
Marty Martin 13:20
Yeah, I mean, it's the same kind of dilemma that I, you know, I've been working on house sparrow colonization for the longest time. And one of the difficulties of doing that work is that every invasion is its own thing. It's sort of like every colonization of a lake is its own thing. So, you know, your point, Andrew, about the power of experimental evolution is establishing causality. But if there's so much context dependency, and so many different forces of selection, how do you think about that? Where do you? How do you replicate nature? Like the many, many different ways that things could vary in temporal and spatial scales? You know, that's really tricky. We did, we didn't spend a whole lot of time on the first foray into evolution in nature, which is, you know, the descriptive studies. You alluded to the Darwin's finches, and many different things that have been tracked through time. That's neat, because it sort of tells us you could describe across lots of different contexts and get some generality. But when you guys are designing your experimental, natural evolution studies, how do you think about this ridiculous diversity of parasites and temperature? And all these different factors, how do you go for generality? Or is that something that you look for?
Andrew Hendry 13:35
So how do we think about this complexity of nature? I mean, for me, personally, I tried, in essence, not to try and fight it, right? It's there. It's real. And so I don't think you can really replicate natural environments very well. I mean, people talk about semi -natural settings like mesocosms or things like this. I jokingly refer to them as semi-unnatural because they're not real setting. So our goal really is to just I use real nature, experimentally. And I don't mean like going in and changing environments. I mean, when you have an opportunity to layer an experiment on top of natural variation, among locations, then that's the perfect experiment for me, because it tells you something new. It doesn't, it might not be the easiest way to figure out like, what's the exact causal effect of one specific thing, you can assess the effects of these different environmental forces in the context of real variation in the real world with all of these things. We've been talking about parasites, predators, competitors, microbes, everything is still there, people, like people walk across the landscape to if they're going to change evolution, then we want to know that, and we want to know it in the context of everything else that's going on.
Katie Peichel 15:46
I mean, I think what we're trying to do here versus sort of the traditional evolutionary experiments, where you're just looking at what you see now, and trying to infer what happens, you know, in the evolutionary past here, we at least know what went into those lakes in terms of phenotype and genotype. We know sort of what the baseline ecological conditions were, we're going to know how those change. And so what's interesting here is not whether things are this exactly the same and each of these replicates. But can we explain what's happening based on our knowledge of what went in, and how sort of ecological conditions and genetics and phenotypes changed over time? So we're sort of taking advantage of that variation, and asking, does it have predictive power, in sort of what we see? So if everything were the same, it would be sort of a boring experiment.
Marty Martin 16:53
Let's talk a little bit about these organisms that we mentioned a few times these stickleback, so they occupy both the ocean and adjacent freshwater systems, and for the longest time, we thought they were the same species. And it turns out they're not. It seems that freshwater sites have been repeatedly colonized by these oceanic forms, both in North America and Europe. And there's this really rapid evolution. We were talking about guppies, but rapid evolution in this taxa too, in these newly arrived freshwater populations. So tell us more about this. What were the sort of first studies about this rapid evolution? What were the traits that were being tracked? How did this whole study system start?
Katie Peichel 17:29
Well, I mean, sticklebacks have been studied for a really long time as behavioral model systems, particularly in Europe, but then it was worked by people like Tom Reimchen in on the Haida Gwaii in British Columbia, and Don McPhail and Mike Bell, who started noticing all of this amazing morphological variation in sticklebacks, and thinking about that from an evolutionary perspective and an ecological perspective. And so a lot of the initial studies were really focused on bony sort of external skeletal traits. So three spined sticklebacks have three spines on their back. They have spines on their belly. They have these big bony lateral plates along their side. And marine sticklebacks are really heavily armored. They've got big spines, big plates. But when the fish go into freshwater, they often lose that armor. And this is really seen consistently. And so you know, people have tried to understand sort of what are the selective forces that are acting on on these traits? You know, why do they evolve so rapidly?
Katie Peichel 18:32
One insight into why they've evolved so rapidly comes from actually studying the genetics of these traits. And so back in the early 2000s, David Kingsley and I started using sticklebacks as a model system to understand the genetic basis of this morphology of, morphological evolution in general, and we focused on these skeletal traits. And so it turns out that, for example, the repeated loss of bony plates in stickleback is due to mutations in this gene called EDA or Ectodysplasin, but what's crucial about this is that the freshwater variant, the freshwater allele is actually hanging out in at low frequencies in the marine population.
Art Woods 19:10
So it doesn't have to arise de novo.
Katie Peichel 19:12
Exactly. And so it's sort of this, I think, the general picture that it's emerging and stickleback is that there's a lot of these freshwater adaptive alleles that are sort of hiding in marine populations, oof standing variation, and then as soon as the fish move into freshwater, there's selection for these freshwater loci. And it's the biology of the stickleback that makes this happen. So the marine sticklebacks go into freshwater to breed, and they're there occasionally sort of hybridizing with freshwater residents, sticklebacks, sort of picking up these freshwater alleles and there's been and a lot of these alleles are old, they're eight to 10 million years old. So even though the modern freshwater populations we see are only their post glacial they're 15,000 years old, but there's been these repeated rounds of glaciation and deglaciation occurring over the past 20 million years. And so sticklebacks have been doing this for a long time, and sort of building this sort of set of freshwater adapted alleles.
Art Woods 20:15
Yeah, that's really cool. I wondered about the persistence of those freshwater alleles in marine environments, because it feels like if selection so strong... well, I guess we haven't we haven't established that. If evolution is so rapid when they go into freshwater that sort of implies very strong selection, but maybe very strong selection against freshwater alleles in marine environments, so why do they persist in marine environments? I don't know. That's a convoluted sort of set of logic. But I think you just answered that.
Katie Peichel 20:40
I think that these alleles, these freshwater alleles are mostly recessive. And so they can sort of hanging out in the marine environment. But to be honest, we know nothing about selection in marine sticklebacks, because they're really hard to study because they're tiny fish in a very large ocean,
Art Woods 20:56
Right, a needle in a haystack.
Katie Peichel 20:57
And we only study them when they come into freshwater to breed when we can sort of catch them.
Andrew Hendry 21:01
So I just have to interject here, Katie, because when we were in Alaska, this year after our experiments, a bunch of us went out on like a whale watching trip. And now we're seeing humpback whales and things like that. And with those humpback whales, I mean, they've got to be eating stickleback, Katie. So I mean, we were going to do a study on you know how whales select on stickleback.
Art Woods 21:26
Awesome.
Andrew Hendry 21:27
I mean, I'm just kidding. But somebody somebody is going to do an experiment on that or not experiment, but a study.
Marty Martin 21:32
So Andrew is the idea that this armor is to keep the fish from going through the baleen plates in the humpback whales.
Andrew Hendry 21:40
No, there was no idea whatsoever. I just thought I didn't go that far. Okay. Anything that eats anything that eats stickleback right is going to probably impose selection on them. So selection is basically nonrandom mortality or reproduction, that is in relation to some trait or genotype. Right. And so, you know, we know that like armor plates evolve from Katie's work, partly because of predation from predatory fishes or birds or things like that. But you know, what would be the selection from a whale eating marine stickleback? Right? I mean, it's not going to care about the spines as my guests are the lateral plates. But it could really influence behavior of stickleback, right? Because if they're foraging in the open water, and maybe there's ways in which they can sense the pressure from a whale coming and get out of the way, or more to the point maybe that doesn't have selection from whales whatsoever. But I just thought it was kind of a cool thought that these whales are eating fish in the environment where there's millions of stickleback, and who knows maybe there's strong selective factor on on stickleback, we need to start getting some whale stomach content.
Katie Peichel 22:46
I mean, also to say like, we still don't really understand why there's selection in freshwater for low plated stickleback. This is, you know, something that we despite lots of effort from lots of groups, including mine, we still don't really know why.
Art Woods 22:59
And so what's the best working hypothesis there?
Katie Peichel 23:02
So you know, for example, it could be that there's just these bones are sort of resource intensive, and that in freshwater, there's sort of low calcium or phosphorus, and you just get selection against building plates. My lab tried to test that idea. We grew fish with that we controlled the genotype of EDA. So really, that was the only thing that varied and looked at phosphorus. We grew the fish and low and high phosphorus and there was like, zero, like literally zero, zero. Differences in growth. So
Marty Martin 23:38
You do the work though, right? That's a good experiment it ain't bad.
Katie Peichel 23:41
That's what I told my devastated graduate student. Yeah. And you know, the other idea would be predation so that in freshwater, there was a difference in predation regime. And so one idea is that these spines and plates are sort of surfaces that macroinvertebrates can sort of grab on to and eat juveniles sticklebacks. The experimental evidence isn't isn't great for that. I really, I personally think it has to be something abiotic. The other thing about that, well, that the EDA locus actually encompasses that's under selection and encompasses two other genes, which are sort of immune related genes. So there could be some immune function, we still really don't know,
Marty Martin 24:23
Some kind of pleiotropy, then.
Katie Peichel 24:25
It could be pleiotropic, that there's, there's pleiotropy. And again, getting back to our earlier point, there doesn't just have to be a single form of selection acting on this locus. But it could be multivariate and there's pleiotropic effects of this locus.
Marty Martin 24:38
Well, I'm going to suggest that your next year's study, you go out and grab some of those humpbacks and introduce them into the lakes, and we'll see how that goes.
Andrew Hendry 24:45
Oh,yeah.
Art Woods 24:47
Wow now there's a fundable idea, Marty.
Andrew Hendry 24:49
So there's a technique I was thinking that there's a technique where you can get gut contents from animals without killing them and it's called gastric lavage, where you stick a, you know, like a syringe down their throat and squirt water and so they barf. So we could also do that with whales? I suppose.
Art Woods 25:08
It's a big syringe.
Katie Peichel 25:09
I'm gonna let Andrew do that one.
Andrew Hendry 25:12
Oh well, I just can't imagine the animal use protocols that would need to be able to do that kind of work. I also just wanted to mention a couple of really interesting historical anecdotes, and one of them is that Darwin talked about stickleback, and it was in his book on sexual selection. And I was trying to come up with a quote, and I realized that right sitting right in front of me, I have a cup, like a ceramic cup that my wife had painted, which has the quote on it, and I was searching for it online and it's standing right in front of me and the quote is, "The male salmon is as pugnacious as the little stickleback."- Darwin 1871. So Darwin was interested in behavior of stickleback and he was sort of talking about male aggression.
Andrew Hendry 25:56
And then interestingly, the other thing I wanted to mention is Niko Tinbergen, who won the Nobel Prize for Medicine along with Conrad Lorenz, and who was the...
Art Woods 26:07
Karl von Frisch
Andrew Hendry 26:08
Yes, so Niko Tinbergen won the Nobel Prize partly for his studies of stickleback, where famously he would have a stickleback in his aquarium by his window at his house in the UK, and a red milk truck or mail truck I can't remember which would go by, and it would like trigger this male stickleback who will start displaying like crazy, because he saw that he thought it was a red throated male stickleback that he had to interact with. So I just think it's kind of fun to think back. like, from the very origins of evolutionary biology, you had stickleback there providing some sort of contribution.
Marty Martin 26:47
So you know, one of the things that surprised me, is this focus on the bony plates. I mean, if the colonization of freshwater, you know, how does ion balance work? Has water balance work? Is this something that's been intensively investigated and found not to be all that surprising, or all that illuminating? Or what's going on in that front?
Katie Peichel 27:05
I think it's just the plates were sort of an easy focus, right? Because you can take the fish, you can stain them, and you can count them. But physiological traits are just as I mean, Art can tell us, are harder to measure. And I mean, there's of course been a lot of work on beautiful work on behavior as well in stickleback. But I think now, at least in my lab, and I think many people are, and Dan for example, are thinking about, you know, immunological traits, how parasites are differing between marine and freshwater, how physiological traits, because these are probably also really important targets of selection. And, for example, if you sequence the genomes of a bunch of marine and freshwater sticklebacks, you get, you know, 100 regions of the genome that are highly differentiated.
Andrew Hendry 27:52
Including physiological regions yeah.
Katie Peichel 27:54
Exactly. So there's clearly lots of other things that are going on. And we just don't, don't understand them very well.
Andrew Hendry 28:00
So I just it is true that some of the sort of the classic genomic work on linking genomics to ecology and stickleback was on these these plate morphs. But as Katie was also just pointing out, there's hundreds and hundreds of things that differ both between marine and freshwater and among freshwater populations. And really, people have focused on those lateral plates, partly because they're really obvious, you can see them you can count them. And because they're they fell really neatly into what you would call a Mendelian trait, basically, where there's, you know, three, two alleles and three genotypes, and those explain the massive amount of variation. So you could actually genotype, you know what genotype you're looking at, just by looking at the fish, because it corresponds so nicely to the EDA genotypes, give or take. And so, there is a lot of focus work on that, because it's kind of just really convenient to study and it works just really well. But there's tons and tons of work on these much more complicated traits, that is really the more typical situation for most of the traits that stickleback are showing.
Katie Peichel 29:04
I mean, people have also, for example, focused a lot on the trophic character, like the bony structures of the head that are important for eating different food resources. So I mean, these are crucially important. So like, for example, the gill rakers that fish used to sort of siphon their food, you know, fish that are eating large macroinvertebrates have fewer and larger gill rakers and fish that are eating zooplankton have more and longer gill rakers. And so, you know, from both the phenotypic perspective and also the genetic perspective, those have also been a subject of study. Those are unlike EDA, those are traits that have a much more complex genetic architecture, some more genes, genes have smaller effects, etc. And that's probably more typical of traits that are under selection in stickleback.
Art Woods 30:08
So I mean, you know, there's several other systems in which people are studying long term experimental evolution in the wild, you know, one that comes to mind that's, you know, at least semi-related to yours is all of the work on the guppies in Trinidad, also a fish system, also interesting movements of fish to create new populations that have experienced new sets of conditions and undergone very rapid evolution. Just overall, what have we learned from the guppy system? And you know, why do we need an additional set of experiments on sticklebacks on you know, somewhat similar things?
Katie Peichel 30:42
It's good that you didn't review our grants.
Art Woods 30:46
No, no, no. I'm very enthusiastic.
Katie Peichel 30:48
No, no, no, no, I'm teasing. I'm teasing. So we'll maybe Andrew you could talk about the, you know, the Guppy system way better than I do.
Andrew Hendry 30:55
Yeah, I can mention because I've worked on the guppy system as well, including experimental introductions. And so I have some experience with that. I mean, the way all of these experiments started was just to prove that evolution occurred rapidly. That was really the context for the first 20 of these types of experiments, right? Because nobody believed going back 25 years ago, the vast majority of people thought that evolution was so slow that you could never access it in nature with vertebrates, for example, in any sort of experimental way. And so people were relying on these massive environmental contrasts that normally occur in much older populations, and then just moving them between those contexts. And then measuring how fast things are changing and then confirming that it was indeed evolution. So the vast majority of what was shown by that earlier work was simply that, yes, evolution does occur really rapidly. And to some extent, it's predictable.
Andrew Hendry 31:52
For example, if you take guppies, and they're in a high predation environment, and then you put them in a place without the major predators, then they will evolve a suite of traits that tend to be expected in an environment that has fewer predators. Now, since then, people have been more focused on some experiments to try to get additional insight into the questions such as, how predictable is that evolution? How repeatable is that evolution? Then you need to do replicate experimental introductions with known sources. Now, I'm not sure I know what the answer is, I think I'm gonna defer to Katie, on saying what these experiments actually tell us about how parallel or how repeatable evolution is or is not.
Katie Peichel 32:38
I mean, I guess in terms of repeatability one thing from the guppy experiments as they started with the same starting population, right? And so then, you know, you have the same source of genetic variation going into these replicates. And so you might say that there's a bias there, because you've sort of started with the same, with the same starting population, and also limited genetic diversity because they started with a single population. So you could say, well, maybe there was some weird sort of genetic variants that were present here that sort of forced things down a particular pathway.
Katie Peichel 33:14
We got around that a little bit in our experiment by starting with, we pooled four different populations to make us a so-called benthic pool, so adapted to feeding on macroinvertebrates. And then we pulled another set of four populations that were limnetic-like adapted to feeding on zooplankton and so we sort of mapped to maximizing that of genetic diversity in our starting populations.
Katie Peichel 33:37
So that's one difference with the guppy experiments is sort of more populations went in. Also, we're sequencing the genomes of all of those fish. So in the guppy experiment, they don't have access to genome sequences from those fish. So they actually can't tell you what are the genetic variants that went into went into these replicates.
Art Woods 34:00
So you'll have a lot more detailed information on the starting genetics.
Katie Peichel 34:03
Absolutely. That's like a super cool component of what of what we're doing.
Art Woods 34:08
Totally
Andrew Hendry 34:09
That's funny that Katie and I didn't like consult in how we would ask these questions in advance. But as we were talking, I was writing down a couple of things that I specifically wanted to highlight and how our experiment contrasted with the ones previously. And Katie just said them both exactly.
Katie Peichel 34:23
Great!
Art Woods 34:24
You guys are meant to work together.
Katie Peichel 34:26
Andrew and I rarely agree, so
Art Woods 34:30
Noted. Remarkable moment.
Andrew Hendry 34:32
Yeah, but there's no genetic context, right? Because you don't have different genetic starting sources. There's no replication in quotations of the genetic population you're starting with. And so, as Katie was pointing out, that's what our experiments are doing. We were using multiple source populations, and they're replicated in multiple places. And we've created these mixtures of source populations, which is really not done in experimental evolution anywhere. And then yeah, the other exact thing is that we have, we will have vastly better information on the exact set of genotypes that went into these populations. Like, Katie just, I just think you should talk about the scope of the genotyping that's being done here? Because it just blows my mind.
Katie Peichel 35:17
Well, yeah. So I mean, literally, we had about 10,000 fish that went into these lakes. And we are doing whole genome sequencing of every single individual fish that that found that these populations, so it's a lot of sequencing. So you know, you write the grant, you're like, oh, this would be super cool. And then you're, you're faced with that, like, "Oh, my God, how are you gonna sequence the genomes?"
Art Woods 35:41
It's the oh, shit moment when you get the grant, right?
Katie Peichel 35:44
Totally! And just just just extracting the DNA. And we had these, I mean, these were live fish, right. So we had to take tiny, tiny fin clips, so that the fish would survive the transplants. And so it's extracting DNA from these tiny fin clips, and then doing the whole genome sequencing on those. So I'll just give a shout out to the folks that McGill, who are actually doing the sequencing for us,
Art Woods 36:08
How many are done right now?
Katie Peichel 36:09
Um, I'm not sure. Actually, probably I know we have DNA is from about half of the fish.
Art Woods 36:16
Still gotta like piece them all together, that kind of thing?
Katie Peichel 36:18
Exactly. So then it's sort of a big bioinformatics project
Art Woods 36:22
Sounds grand, sounds grand.
Marty Martin 36:25
The grant that you guys have is that is that a single NSF grant, or what's the funding mechanism, because we were confused, Katie, because you're in Switzerland now, and not sure how that worked.
Katie Peichel 36:35
I mean, maybe a little bit of the history first is that basically, we didn't have a grant for this project, just the opportunity came up. And so we all sort of threw in slush funds to make it happen and sent people. And then the idea was to get money later.
Marty Martin 36:53
Good.
Katie Peichel 36:54
One of the crucial things was to get whole genome sequencing of every individual that went into these lakes, which is, you know, 10,000 individuals. So that's a lot of money. And so because I'm in Switzerland, the opportunity to get large sums of money is a little bit larger than it is in Canada, or the US.
Katie Peichel 37:12
And so I applied for this grant, it's like the European Research Council grants, so these big grants in Europe. But Switzerland got kicked out of that system, and so they replaced it with their own system. And so I applied for that to get the money to do the whole genome sequencing. So it's been, I would say, just opportunistic that all of us are applying for money, where we think we can get it to fund the project.
Marty Martin 37:37
Gotcha.
Andrew Hendry 37:38
I think that the way people think that most science proceeds is that you have an idea, and then you search out money to get it. And then you go ahead and you compile the people to do the project, and you go out and you actually do the project.
Andrew Hendry 37:51
But this one proceeded quite differently, which meant that it was kind of had some opportunities and some constraints that weren't there otherwise. And basically, what happened is we heard about the opportunity to do this research at a meeting, a scientific meeting, and literally had the had to start the project within a year. And there's no way you can get funding on that kind of timeframe, or arrange students or anything like that.
Andrew Hendry 38:15
So instead, a bunch of the PI's got together and said, "Wow, this is an amazing opportunity. Let's just do it ourselves." And so we all sort of cobbled together money off of our research grants, which is our existing research grants, which is one of the cool things about sort of these semi untargeted research funds is that you can actually take advantage of opportunities like this. And then it was just kind of amazing. Because we, the first year, it was essentially all PI's in the field, there were no students actually, on the project, there were some students who were helping out, but they weren't actually on the project. And that never happens really, where you just get all the PI's doing the field work anymore.
Andrew Hendry 38:56
But I just think it was like kind of a cool way in which it started, which doesn't really happen anymore, where you just hear about something and then everybody just goes for it before you have everything all, you know, all funded and students in place and all of that it was kind of a unique experience.
Art Woods 39:13
It sounds like a semi ideal way to do science. I mean, it's a great way for you guys to sort of get together and crystallize everything, right?
Katie Peichel 39:20
I think the best science grows organically. And that maybe gets back to the question that Marty just ask us like we've all been, well, Andrew and Dan and Rowan and I have all been working together for ages. And we bring- we have complementary expertise. And we know we work really super well together. We have fun doing science together. And so I think when Andrew sort of learned about this project, he immediately started grabbing his friends to say: "Hey, this is super cool. Do you want to be involved with this?" And we were all like: "Yeah, absolutely. This is amazing."
Katie Peichel 39:52
So it wasn't like these top-down sort of things where someone says: "Oh, we need to fund research on this." And then you bring together people who've never worked together. This is really a grounds up sort of project that grew from people who knew they enjoyed working together. And we've brought in other people since then, to sort of complement the expertise that we don't have.
Marty Martin 39:52
Did you all come together because of a mutual love of sticklebacks? Or who was the stickleback starter? Who was the matchstick in that part of the relationship?
Katie Peichel 40:25
I would, I mean, Andrew, you could disagree with me, but I would say that our original collaboration was through Dan Bolnick. This was back in 2000s have been somewhere around there, that Dan had this idea to work on parallel evolution, so what drives sort of repeated evolution. And so he wanted to focus on these stickleback lakestream stickleback in British Columbia. And Andrew had worked on those systems. And Dan had worked on those systems. And then they wanted to do some genetic Dan wanted to bring in like the genetics and genomics, which was my expertise. And so we got together at the evolution meetings in Minnesota and started hashing out ideas. And then Andrew's family had Andrew went on sabbatical and Napa at his family's vineyard
Marty Martin 41:11
sounds rough,
Katie Peichel 41:12
And he made us, he twisted our arms and we all went to the vineyard. And we basically put together the first draft of the grant on that trip in between drinking wine.
Andrew Hendry 41:24
So Dan, and I had both been working on stickleback on Vancouver Island in British Columbia. And I published a paper in 2004. And Dan saw an article about our research in like the local newspaper, the Campbell River newspaper. And he's like, wait, what? There's people doing stickleback work in Campbell River, British Columbia that and it's not me, I'm doing work here. And so he contacted me and said: "Hey, man, we're setting the same lakes. We're working on stickleback, you know, we should talk." And then he likes to joke that I showed up at his at his field site or in his field camp next summer with my whole lab and insisted that we take over the place and stay there the whole time period. I don't remember it quite like that.
Art Woods 42:21
So I want to turn at this point to a few more details about your Alaska experiment. I know we've already touched on aspects of it. But I feel like we haven't like actually said in a nutshell, like what the overall experiment is, and, you know, how long it'll run that kind of thing.
Art Woods 42:36
Let's just sort of lay it out. So you got this long term experimental evolution experiment going on sticklebacks in Alaska, maybe just give us the overview of like, how many lakes are these fish going into? How do they get into them? And how long you're going to follow these populations? And just an overview of what you're going to measure.
Andrew Hendry 42:56
So I'll start with sort of the overall design. And then I'll let Katie talk more about like the genomic work and the genetic work that's following from the design. But I did want to say one really interesting thing is that we've all been talking about EDA and these lateral plates. And one thing this experiment does not involve is variation in that.
Art Woods 43:16
Oh, interesting.
Andrew Hendry 43:17
Because they're all freshwater populations. So they're low plated. So I think one thing that's really important to think about is like, why we have the opportunity to do an experiment in nature, we wouldn't advocate people just go out and start throwing things everywhere they want to do so they can study their evolution.
Art Woods 43:32
That's illegal in many, many places.
Andrew Hendry 43:33
Yeah, exactly. You have a very particular set of circumstances that enable this kind of experiment. And that starts with the fact that a lot of lakes throughout the world and freshwater bodies throughout the world, pretty much every environment everywhere, it gets invaded by things that don't belong there, meaning invasive species from some other place in the world, or geographically. And these invasive species often have really massive negative impacts on the environment.
Andrew Hendry 44:00
Now, the specific one that is of concern here is a fish called the northern pike, which is a voracious predator that is really good at killing other fish, small fish. And northern pike is native to North America, but it's only native to some regions of North America. And one region is not native to is the Kenai Peninsula in Alaska. But somebody presumably fishermen wanted to put these pike in lakes so they could fish for them. And these pike then start to spread to other locations. And they're such good predators that they essentially wipe out all the native fishes: any salmon or trout that are in these lakes and all the stickleback.
Andrew Hendry 44:37
So this is a big environmental degradation that the Alaska Department of Fish and Game needs to deal with. And the only way you can really be sure you get rid of this invasive species, remembering again that there's no other native fish in these lakes now, is to actually poison the lakes with a chemical called rotenone. It's a classic chemical used to kill all vertebrate life within a water body, and then you can start from scratch.
Andrew Hendry 45:03
And then the idea is you have to restore the lakes, you have to put the native things back in. And we sort of heard that this was going to occur and that they were going to throw stickleback back in these lakes. And it just seemed like a really wonderful opportunity for us to be able to do an experiment that would tell us basic conceptual and biological questions and evolutionary questions, but also have applied relevance in the context of what's the best way to restore a lake. So in a nutshell, you have, depends on how you count, but let's just say nine empty lakes. They vary in size, but none of them are massive. So what would be a good size?
Katie Peichel 45:41
Well, it took us what 10 minutes to canoe across it?
Andrew Hendry 45:45
Yeah. So you can have a lake that takes one minute, so some of them take one minute to canoe across, and other ones can take 10 minutes to canoe across.
Andrew Hendry 45:54
So we've got nine of these lakes. And we decided to try and understand not just how evolution would proceed within them, but how evolution will influence the lakes themselves. And so we leverage this variation in trophic morphology, that is some stickleback like the feed on the bottom, and they're called benthic, and other stickleback populations and species like the feed in the open water column, and they're called limnetic. And so we decided to put benthic stickleback into some of the lakes and limnetic stickleback into other lakes. So we could see how that would influence the rest of the lake ecosystem.
Andrew Hendry 46:28
And then the other thing we decided to do was to mix benthic populations. So we take we found four really benthic populations, mix them together, and then introduce that mixture into four lakes. And then we found for limnetic, really like sort of archetypal limnetic populations, mix them together and introduce that mixture into four lakes. And then into the ninth lake, we put all of the source population. So we have this mixture of benthic and genetic populations from eight different sources.
Andrew Hendry 47:00
And then the only other additional twist is that in one of these lakes, one of the lakes we put benthic stickleback into, for some reason it didn't succeed, they all died. The only one. We don't know why we have hypotheses, but we don't know why. So we redid that lake. And in that one, we also put a mixture of all the source populations we could get a hold of, which was seven of the eight. So you have four lakes that have limnetic mixtures, three lakes that have benthic mixtures, and two lakes that have mixtures of a bunch of these benthic and limnetic source population. So that's the experimental design.
Marty Martin 47:33
Andrew, how did you decide how many fish to put in each lake?
Andrew Hendry 47:37
I mean, it was a balance between how many would be reasonable to remove from the source lakes, how many we could reasonably handle, because as Katie pointed out, every single one had a fin clip taken and we had to do this in a short period of time. And then the only other thing was, we had long debates on email between Katie, Rowan, Barrett, Dan Bolnick, myself and others, about whether we should just put the exact same number of stickleback into each of the lakes that they're going to receive them, or whether we should somehow scale them, scale the amount put in by the size of the lake. And in the end, we were tipped in the final direction by Alaska Department of Fish and Game who was concerned with putting too few stickleback in the big lakes for them to take off quickly. At the same time, we didn't want to put like 10 billion stickleback into little tiny ones. So we ended up scaling them, not proportionally, but they're scaled by lake size.
Art Woods 48:32
Cool. And what year did all these fish go in
Katie Peichel 48:35
2019. Perfect timing.
Marty Martin 48:38
Great timing, nothing else going on around that period.
Katie Peichel 48:40
But we were super lucky in 2020 and 2021. Because of course, we want to collect fish every year. And one of our colleagues on the project Jesse Weber was a professor at University of Alaska, Anchorage. And so he and Kat Milligan-McClennan, were able to collect samples for us in 2020, and 2021. Cause those are really crucial years, like these early years, some, we think interesting things, are gonna happen in these early stages when selection is probably really strong. So we were super fortunate. And then we were able to sort of mount the big teams in 2022 and 2023.
Art Woods 49:21
How many years are you intending to follow these populations? You know, do you are already see evolution? And are you most interested in phenotypic evolution, genomic evolution, like the linkage between the two?
Katie Peichel 49:34
All of it?
Art Woods 49:36
Okay, great.
Katie Peichel 49:36
I mean at least, you know, I think from everyone's perspective, we're interested in how the sticklebacks are evolving. We're interested in what's the underlying genetic basis of that. We're interested in how the parasites are evolving in these sticklebacks, how that's feeding back onto the lake like ecosystems and so...
Art Woods 49:53
Co I'm understanding that while your team is so large.
Katie Peichel 49:56
Exactly, it's this is really a big collaborative interdisciplinary project. The timescale, you know, like, for example, my grant goes until end of 2027. So that'll be eight generations as one year as basically a generation and stickleback. In these Alaskan lakes, that might be two years. But essentially, we'll have several generations. And we think a lot of interesting things will happen then. But I mean, what we would love is that people continue to study these lakes for forever, as long as there are sticklebacks there. This is a long term experiment. And if people are interested in they have their own ideas about what might be cool about these lakes, you know, that we're sort of bringing people onto the onto the team to study them.
Art Woods 50:38
Okay, so here's one other this is one thing that Marty and I kept thinking about and discussing when we were prepping for this chat. And that's thinking about the roles of plasticity in shifts and traits that you see. And we just wondered, overall, how important is plasticity in shifting some of the traits when things move from marine to freshwater? And then the sort of more abstract version of that question is, you know, do the directions of plasticity, if they exist, do those aligned with the directions of evolution? Meaning, you know, is there a linkage between sort of pre-evolved pathways for plasticity, and what's possible in evolution?
Katie Peichel 51:16
I mean, we know that many of these traits in sticklebacks have a very large genetic component. So they're pretty heritable. If you grow them in the lab, you know, benthic sticklebacks still look benthic. After several generations in the lab limnetic still look limnetic, same with marine freshwater differences. So we know there is this strong genetic component, but there's also plasticity. Jesse Weber, who's involved in the project is actually doing common garden experiments on all of the populations that went into the introductions to actually get at this question of sort of how much plasticity is there? Is it sort of adaptive? Does it go in the direction that would be adaptive or not?
Andrew Hendry 51:56
In this particular experiment, we can actually disentangle those effects, because we can go in any generation, and we can genotype an individual fish and find out what its genotype is. So these are massive replicated common garden experiments, right? Because we can go back and get a pure fish from source lake one- 1, 2, 3, 4, 5, 6, 7, 8 years into the future, right. So we can, we can directly compare genetic and plastic effects in every single generation by individually genotyping fish that we capture from these lakes, and then measuring their phenotypes.
Art Woods 52:37
Yeah, super cool.
Marty Martin 52:38
So let's, if it's okay with you guys, we'll scale out even more and talk about the implications of your stickleback research in the broadest possible sense. So Katie, in your grant proposal, you really early on juxtapose two very cool ideas. And I want to hear what one or both of you think about this. You cast the work that you guys are doing sort of these comparisons between populations experiencing, evolving through time, asking about, I guess you call it parallel evolution. And in that same section, you were talking about convergent evolution, which, you know, you cast as, let's say, wings, of bats versus birds versus insects, functionally the same kinds of things but very different trajectories and genetic bases and all that. How do you think the stickleback work and parallel evolution generally relates to convergent evolution?
Katie Peichel 53:28
So I think what we have in this system is this ability to again to sort of test the factors that might contribute to whether we see repeated evolution or not. So again, I think it doesn't matter to me whether evolution is repeatable in these systems, what I want to know is, can we say, oh, in this lake, we had this genotype sort of take off. And that's why it sort of went in this direction. Or in this lake, there was this weird sort of abiotic variable that sort of went things in this way. And so that will tell us to what extent on this micro scale evolution is repeatable or predictable. And if the answer to that is no, we can't predict anything, then it's sort of hopeless to try and think about macro scale, right?
Marty Martin 54:19
Sure.
Katie Peichel 54:19
But if we can say, oh, in this experiment, what we find determines the trajectories of evolution that we see is really sort of the selective regime. And any sort of genetic changes can make these changes to genetics and is important. For example, that might tell us something about how to look at sort of these broader scale patterns and say, okay, when we see patterns of convergence at the phenotypic level, it probably is driven by the environment, for example, and maybe developmental or genetic constraints aren't so important. So I think there may be some ability to scale up, but this sort of gap between sort of micro evolutionary processes and macro evolutionary processes is a tough one, actually, in evolutionary biology. I think lots of people sort of struggle with how do we how do we sort of bridge these two levels of evolution?
Art Woods 55:14
And if you had to identify, like, a length of time that characterizes that distinction between micro and macro what is it?
Katie Peichel 55:23
That's a good, that's a good question. Andrew do you have? I mean...
Andrew Hendry 55:27
Well I mean, different people say it in different ways. I mean, I think the easiest way, at what appears to be the easiest way to sort of talk about these transitions from micro to macro is whether you have the origin of a new species, right? So if it's within the species, you call it micro and if it's between species, but stickleback, I think highlight how that could be considered a bit of a false dichotomy anyway, because what is it? What is the species in stickleback? I mean, you could, you could take, you know, the three spined stickleback complex and break it up into a whole bunch of different species, depending on what particular criteria you might use. And yet, if we threw them all together, they'd all breed together. Or would they? Because we are about to test that, right? Like, we're gonna know, do all these populations mate with each other? And are they happy to do so? So again, it's almost like a big experiment on testing whether these things are also different species.
Katie Peichel 56:22
Maybe that's maybe that's the micros they can mate with each other. Macros, they can't. How's that?
Art Woods 56:28
I like that. But I mean, okay, so if we just put aside this question of whether there's multiple or one species, like, you know, you're gonna have a short term experiment that looks at, you know, presumably, in the end five or ten years of data about evolution, and you're gonna decide whether it's predictable, what happens in the different lakes. But does that inform say, you know, how these things will look in a thousand years or ten thousand years? I mean, I guess I would still call that microevolution, but it's a much longer time scale, then you know, what any experiment can look at.
Katie Peichel 57:02
Well, I think then that would be really cool, then is to take what we learned from this experiment, because in our, and then compare it to our wild stickleback populations, which have been evolving for, you know, 10,000 years or actually longer, if you think about the sort of evolutionary history of them. And to what extent can we take what we learn in these, these experimental conditions, sort of apply it, and now can we explain what we see in our natural populations which have been evolving?
Andrew Hendry 57:30
I'm gonna bet that 100 years from now someone's doing a podcast on this experiment, right? Because, as Katie said earlier, it's permanent. We're not taking them out, these lakes aren't connected to external water bodies. And so to the extent that people are still interested in evolution, 100 or 1000 years from now, they'll probably still be studying these populations.
Marty Martin 57:51
Okay, so another question. And this is a bit of a selfish one that I'm trying to marry three spined stickleback world with house sparrow world. The work that we've been doing recently, we focus a lot on the individuals that are colonizing new places. And I know when you know, you do this mega experiment, so many different people evolve, and so many different things that you have to do. There's an unbelievable elegance to you know, the mixture of benthic populations and limnetic populations and the introduction to the different lakes. But when you did that, did you pay attention? Were you able to make measurements of any of the traits of the colonizers? Do you expect the pioneers in a natural system to have been different than presumably the, you know, the random grouping that you introduced to the different lakes? Is there something different there in nature where you know, whoever is going to colonize would necessarily be the random subsample that you're putting into the lakes? How have you thought about that?
Katie Peichel 58:47
Well, I was gonna say, I mean, at the population level, at least, you know, because we put in this mixture. We've already designed some, some SNP arrays to figure out the ancestry of the fish that are sort of swimming around now. And these lakes, and not all of the four founding populations have contributed equally. So why that is, of course we don't know. But it's not a 25% across the populations.
Andrew Hendry 59:15
Yeah. So I think, to transition from what Katie was saying, in principle, since we will have the whole genome at high coverage of every single individual that went in, and we took photographs of everyone so we can at least know their external morphology. In principle, we can link individual variation to success in subsequent generations.
Andrew Hendry 59:37
Now, in addition, I mentioned that one of the lake introductions didn't work, and so it was redone. And for that one, I have a student, her name is Alexis Heckley. She was looking at how individual variation and behavior will influence how they move through the lake and then potentially survive moving forward. So this is something that is of interest to us. It's just that when you have like you want detailed behavioral observations like you might do with birds that you're watching in nest boxes, that we can't do because these populations are gonna get so big, that we really can't track individuals very well unless from a genetic perspective, but even then, you're gonna have 10,000 fish in these lakes, right? So, don't worry, there's still a place for lots of this individual bird work that we just won't be able to answer.
Marty Martin 1:00:28
Do you have any expectations on what the Pioneer stickleback looks like? What are the individuals that go into these places?
Andrew Hendry 1:00:35
Yeah, I mean, it's funny, because we did actually have, we did have some debates among ourselves about which population, at the population level right, which populations would be most successful? None of us were right, I think. So for example, one of the hypotheses was that the lake that had the biggest females, the highest fecundity, right, so that lake might, just from a purely demographic perspective, basically produce the most kids and so take over. It did not.
Andrew Hendry 1:01:05
One of the other predictions was that the populations that sort of appear to be most best ecologically matched to the recipient lake would do the best. And we still have more work to do on that. But it's not like the benthic populations universally did best in benthic oriented lakes and limnetic populations in limnetic type lakes, it doesn't seem to map out quite like that. But actually, it makes partial sense, because in the first few generations, there's probably not the high competition, right? Because they haven't fully populated the lake. And so everybody can just eat what they want to eat, and it's not going to be depleted. And therefore, it's like this old argument about what people call hard versus soft selection, right? You know, and initially, there's just no density dependence, so everybody does, okay. And you might not see lots of evolution until, you know, I don't know, 10 generations from here.
Katie Peichel 1:01:56
Although now the densities in those lakes are super high. Yeah, it's incredible how many sticklebacks there are, so I would say now there's probably competition is probably really strong.
Marty Martin 1:02:08
Well, Katie, and Andrew, I mean, this is really been fun and dumb. I guess we should let the audience know that this might not be, probably won't be, the last time that we talk about stickleback evolution in your system. The hope is that next year, we'll do some version of this live together in Alaska. And if you can foreshadow a little bit what you think we're going to be talking about, Dan Bolnick, we mentioned him 45 times at this point, he wasn't able to join us, but I know that he and others are interested in the evolution of gene regulatory networks. And that's something that I'm really excited to hear about. But either maybe a little bit that you could say about that, or just in general, what do you expect us to be talking about in a year or so?
Katie Peichel 1:02:47
Andrew, you want us to make predictions, make a prediction,.
Andrew Hendry 1:02:51
The predictability of podcasts> I mean, we every year, there's a series of things that we do. And that includes a lot of the stuff that Dan Bolnick leads on parasites and gene expression and immunology and things like that. And so I imagine that we'll do a lot of discussion looking at individual parasites and how fish are responding to them. And like this massive, interesting can of worms in a good way. There's also like a whole ton of work trying to understand how the behavior of the sickle back is evolving. And that's a really cool thing to look at, because you can you know, get in your wetsuit and go take a look at, you know, the who's mating with who and how that's affecting anything. In addition to that, we've got a whole bunch of other sorts of experiments that we're mulling through right now as to what is the best next step in this project. And so I'm not going to predict exactly what will happen, apart from those first two things I mentioned.
Katie Peichel 1:03:48
But I do think in a year, we'll have some early results in terms of how the phenotypes are evolving at the morphological level, we might have a little bit more genetic data, sort of these patterns of sort of assortative mating, and maybe why certain populations are doing better. So I think I think we're going to start to have our first sort of sets of results that we could really talk about next year.
Art Woods 1:04:11
b Well, it's probably a good time to start wrapping up. Before we go, though, we always like to ask our guests one last question, which is whether there's anything else you would like to say that we haven't asked you about?
Andrew Hendry 1:04:23
I mean, for me, I think the important thing is that, you know, podcasts like this give the impression that there was like two people or three people who, you know, like, figured everything out and did all the work, and I think what's really important for me is to recognize that this is a team effort by a whole bunch of people, all with complementary levels of expertise, who were assembled, as Katie pointed out, because we all like each other and work well together and complement each other in what we're doing. And I think it is critical to recognize that those other people are equal partners in this. It's not the people you're talking to and that the audience is listening to, it's this massive set of people, of which we are just one divided by n of the contributions to this project.
Art Woods 1:05:08
Yeah, no great point. It's a impressively large and diverse team. And, you know, we expect to talk to different subsets of you in the future.
Katie Peichel 1:05:16
The other thing just to add to that, is I think we all feel like, this is sort of the opportunity of a lifetime. You know, I never imagined we would be doing, I'd be involved in such a cool project, and it's really just a lot of fun. And also, to emphasize that we really, we want this to remain just a collegial and fun group. And it's really important to us that our students and postdocs get credit and that we, at the end of it, that we're all still friends, and like each other. That it's cool science, and we want to just have fun doing it, so.
Andrew Hendry 1:05:51
Yeah, there's no experiment like this anywhere. It's just completely unique. And so the opportunities are just really like, through the roof and having a bunch of like, colleagues who've worked together in the past and are bringing in new people who we know will work well. And it's just, it is the funnest, it's you know, I feel like I could have retired Katie, after I did the introductions in 2019. I mean, I literally could have retired and my career would still be roaring for 100 years, I'm guessing, even if, you know, even if I'm not like on every paper, I just feel like the experiment. I've done the experiment of the life. Sorry, I don't mean, I mean, we've done the experiment of a lifetime now. And I mean, I don't intend to retire on that. But, you know, I feel like I could have and it's like the one thing that I was a big part of helping out that will never be there's nothing like this anywhere. And probably not for quite some time. Although I hope other people get inspired to do similar sorts of work. And maybe I almost hope will be obsolete in a few years because someone else will have done something bigger. Almost hope.
Art Woods 1:06:59
Well, super looking forward to talking it over next year.
Andrew Hendry 1:07:01
Great. Great. That was great. That was that was that's the funnest podcast I've been on.
Katie Peichel 1:07:06
Thank you both for the chance to chat about it. It was fun.
Art Woods 1:07:09
Yeah. Thank you
Marty Martin 1:07:21
Thanks for listening. If you like what you hear, let us know via X, Facebook, Instagram, or just leave a review where you get your podcasts and if you don't, we'd love to know that to write to us at info at bigbiology.org
Art Woods 1:07:32
Thanks to Steve Lane who manages the website and Ruth Demree for producing the episode.
Marty Martin 1:07:36
Thanks also to Dayna De La Cruz for her amazing social media work and Keating Shahmehri who produces our awesome cover art.
Art Woods 1:07:42
Thanks to the College of Public Health at the University of South Florida and the National Science Foundation for support.
Marty Martin 1:07:47
Music on the episode is from Poddington Bear and Tieren Costello.