Kevin Roberts

Saintsing:

Hi, you're tuned into 90.7 FM. KALX Berkeley, I'm Andrew Saintsing. And this is the graduates, the interview talk show where we speak to UC Berkeley graduate students about their work here on campus and around the world. Today I'm joined by Kevin Roberts from the department of integrative biology, open to the show Kevin.

Roberts:

Thanks for having me.

Saintsing:

It's great to have you here, we were kind of like almost lab mates, honestly, even at that point. Yeah. We know each other's stuff pretty well. So I know that you're a, a, you're a book guy, right?

Roberts:

Yeah. Yeah. I would say, oh, you know, it sounds a little weird, but yeah, I guess it's fair to call myself a bug guy.

Saintsing:

Why is it sound weird?

Roberts:

I guess you sort of are a picture comes to mind where it's kind of like Spiderman, but slightly, maybe six legs instead and less webs. But

Saintsing:

Yeah. I want to be like a weird bug guy. You're like a cool book guy.

Roberts:

That'd be like most bug guys would be pretty cool though. Cause yeah, bugs are cool.

Saintsing:

So you've always like insects.

Roberts:

Um, no, no. So I actually used to, uh, really like or dislike them and, well, no, I was neutral towards insects. I really disliked spiders and I still am lukewarm about spiders. Um, but I kinda got into them in college or like, I guess undergrad, we had to take an organismal biology class and it was in the peak recession times. So they like cut a lot of classes and they weren't, it wasn't a lot available. And my like advisor, counselor person, um, was the professor of the entomology class. And he was like, why don't you just take this? We could make it count for that. Um, and I had never considered it. I think I kind of wanted to work on like amphibians or something and I thought they were interesting and I took it and it, yeah, they're just crazy. They're just like little aliens. They breathe through holes in their body, like the side of their body and just do everything like turn into completely different forms.

Roberts:

Liquified their bodies fly. It says, yeah, it's all there. Cool.

Saintsing:

What did you study about bugs?

Roberts:

One of the other things I guess I should say that I find most interesting about insects really is how wide a range of environment they can tolerate. So like a lot of what I work on involves cold and one really cool thing that a lot of insects can do is tolerate, freezing and not die, which is, it's not like a unique to insect phenomenon, but there's like only a handful of vertebrates that can do that. And it just, yeah, it just seems so crazy to me. Cause like I grew up in California where like, you know, uh, 50 Fahrenheit seems cold and there's these beetles that are tolerating like zero.

Saintsing:

Just kind of like go into deep freeze and then just come back when it's they go like offline and then come back online when it warms back up. Yup.

Roberts:

Yeah. So I guess there's a few different approaches to kind of call that insects deal with. Well, like a big aspect of my research is mostly focused around seasonality. So there's these like seasonally prepared states that they can be in hibernation would be an example for mammals insects it's typically called dialogues or it could be quiescent. So basically they go into dormancy. So there's this long period of preparations. They can tolerate cold, but they're already inactive when they have the cold, like experienced the cold temperatures. So active insects can also, when they're exposed to cold, a lot of times they lose the ability to coordinate or I would like to still, I guess, maintain muscle function and they just kind of fall on their backs or like fall over and they just sit there and until they come back and its called "chill coma" and say are essentially in a coma from being cold.

Saintsing:

So there's a difference sometimes insects, all of a sudden, like if this were happening in a lab, they wouldn't really prep for being cold, but in the wild they kind of know seasonal cues. And so they kind of prepare for the cold. And is there a difference in that end experience for insects?

Roberts:

Yeah. Well, yeah. Yeah. So, I mean, I guess they can get a bit more complicated. So partially also what I work on is seasonal. Oh yeah. So I work on a winter, like how, what insects do in winter. And there is still acute cold exposures that can occur in winter. And I do partially work on that. Um, so there's still see seasonal preparedness and then cold that happens in that time that they deal with. And yeah, I guess the mechanisms are a little bit different just in terms of time that they have to maintain or a lot of what happens when they're in this chill coma, not seasonally induced cold is they lose like that. They're unable to maintain ion balances. So their nerves basically just don't function. So they can't like coordinate a lot of stuff and they just can't move, I'm really sure how you deal with that.

Roberts:

There's like subtle adjustments you can do to like fix your cellular membranes and stuff to prevent leakiness of the ions. But typically with the seasonal shifts that insects do, at least the ones that I work on, I'll speak specifically about the one I work on.

Saintsing:

What is that?

Roberts:

It is a Sierra Willow beetle. So it's just this little automobile that eats Willow in the Sierra Nevada as well. It is distributed across semester in the United States and yeah, it's, it's a high elevation in the Sierras and it just looks like a little lady bug, but reverse colors. Um, so this is black with red pattern a little bit. It's really cute for, for a bug, you know? And they, they don't really do anything particularly interesting in terms of what people normally think of. It's not like, um, pine beetles that are this large like pest, I guess they're just really interesting because they live in these really variable environment and the CRS because California is fairly drought, drought prone. So there's a lot of variation in snow that happens, which impacts like temperature and stuff like that too.

Saintsing:

And then, sorry, you were about a, what, uh, I'm gonna say in the context of your Willow beetles.

Roberts:

Yeah. So what these Beatles end up doing is they just put a bunch of like, oh they, so they specifically use glycerol, but basically they just pump a bunch of stuff into this open fluid that's floating around them to increase just how much stuff is in there. Cause that disrupts ice crystals from forming, or it controls the rate at which it does, but it disrupts it typically. And yeah, so they, they do that. I think there's a lot of equivalents of like frogs have a similar strategy. They can freeze, but they use sugar, they just put glucose all over themselves to prevent it. And some insects do that as well. But yeah, they pretty much just like decrease the water to stuff's ratio in their blood.

Saintsing:

So they just don't. So the ice doesn't kind of like, you know, like a situation at a soda can in the freezer, like the ice would kind of just pop their selves.

Roberts:

Yeah, yeah, exactly. Especially as on that scale, the ice crystals are like a lot more stabby kind of grow like little pyramids. Yeah. And so that's actually an interesting problem that I did mention earlier that some insects can freeze, um, and survive. But as to the ones that, that want to freeze and survive, don't want to suppress what temperature they cool or like what temperature they freeze that. So, um, if you get it too low by adding a bunch of these like Saul Utes and they're like glucose or glycerol, once the crystal formation starts, it like goes fast. So it like expands really rapidly. So typically what they try to do is initiate. And when I say they try and it's not like they're making the conscious decision, but they have this strategy of trying to initiate, freezing at higher temperatures so that they can control the rate of growth. So it doesn't like damage as much. Yeah. And that's, that's uh, my, the Beatles I work on do.

Saintsing:

Cool. So they're uh, the water in their cells is freezing above zero is what you're saying above zero degrees Celsius?

Roberts:

I think it's, it's typically the water outside of the cells person that it's freezing. I think it's, it's very problematic, problematic if it's inside the cell and it so usually like, I guess seawater has a lower freezing temperature than fresh water because there's a salt in there and stuff. Right. It's, it's a similar, I guess, phenomenon to what, what I was talking about inside the beetle. So just like most living organisms are going to have a freezing point below, I guess zero Celsius would be the freezing point of just water in a room. And the temperature you go below that is called your super cooling point. It's like the ability to cool below zero. And there's some insects that can, you know, uh, delay freezing until minus 20 Celsius. And then like beetles, I work on that, do control the ice freezing or dies crystal growth rate, uh, and survive, freezing do it about minus five degrees. And then they can tolerate down to minus 15 before they die. Yeah. So they're kind of like doing it. I say warmer temperatures, but it's still cold, relatively warm.

Saintsing:

And so these insects at some point, what, what kind of what's their life like? Are they like how much time did they actually spend as like active living things? I mean, you know, they're always living when they're alive, they're always living things, but you know, sort of life.

Roberts:

Yeah. So they live for one year, they have one full life cycle and then typically at least the Sierra populations that I work on spend about eight to nine months dormant. So two-thirds to three-quarters of their life, just, yeah. Dormant. There are a couple of populations of these beetles that live on the Mendocino and Sonoma coast. And I think they get a little bit more time because it's just less seasonal there. Well nicer or all year, but yeah, Sierras are pretty cold until they're not, you know, like usually June to like August or something, they're, they're pretty yeah. Trying to fit in, I guess, reproducing and growing and then preparing for winter. Yeah. It's pretty crazy. There's actually one, uh, there's a species of, oh, I'm probably gonna mess this up in some sort of caterpillar, like moth that lives in the Arctic. And I think the specific example I was reading about was in Greenland and it, it takes like seven years for it to become an adult. So it like molts and then spins winter and then comes like comes around again and then maybe molts again. Yeah. So it takes seven years to actually finally get there.

Saintsing:

And it's like for that caterpillar, I guess it would be like, it would have a time period of like a month or something. Just be a larva. It's a, I dunno know, is there fine grass to eat there?

Roberts:

Yeah. I mean there's like little shrubby things that they can eat. Yeah. Yeah. So they're probably living well, I guess if it is like a month of growing season, it's, uh, 11 and 12, so it kind of lives in dormant, you know? And then I, I mean most of the terrestrial habitat, well I guess most of the gestural habitat in the, world's not most a big portion of it is in the Northern hemisphere, a pretty high latitude too. I mean like Canada, Russia, these huge landmasses and they get really cold. So a lot of insects just have to deal with this. Um,

Saintsing:

It's just the reality for a lot of living things that you got to spend a lot of your life, not actually living it.

Roberts:

Yeah. Or I guess the other strategy of like being able to tolerate winter and what the insects I work on too, a lot of birds just kind of avoid winter and leave. And I guess there's a lot of insects that migrate as well. Right? Like this is just something we're kind of getting an idea of how much they do, but like monarchs are pretty classic example. Right. So you just have to either avoid it or tolerate it or not survive it.

Saintsing:

So you're, you're generally studying how these insects tolerate the winter. And so is there a kind of like a specific thing that you're studying in that? Like, is there a main question that you're interested in around how these insects are toleranting winter?

Roberts:

Yeah. Yeah. So I guess most of my dissertation work is really looking at the role that snow plays in how insects survive winter or what stresses they experience over winter, which I kind of alluded to a little bit, there's a lot of variability in snow, in the Sierras and these Beatles, that experience. But, um, yeah, so snow is a really good insulator that can buffer, I guess, everything, but let us know from the really cold air temperatures. So usually temperatures below snow don't really go below freezing much. Yeah, at least soil surface, if there's enough snow. So a lot of insects, a lot of organisms use this space to kind of survive winter, but there's increasing prevalence of drought and decreased winter snow cover in California, at least, or in the Sierras. So they're going to kind of be winters in the future may start to shift a little bit, less snowy and more cold. So as kind of climate or the world in general has increasing mean temperatures. There's actually an increasing cold that insects that rely on snow, but don't have it, but we're going to be experiencing. And there there's really cool paper, I think in 2003, that called it colder soils in a warmer world. Peter Grossman. That is, yeah. I think it's a really interesting like paradoxical thing, climate change. So yeah, I'm interested in like what that looks like across the mountain.

Saintsing:

So like, um, how it varies as you get higher up the mountain.

Roberts:

If you just think of a typical mountain or even like a cartoon caricature of a mountain, right. There's always snow at the peak. And then it goes away a little bit as you go down and temperature also changes across the elevation where highest elevations are cold. So kind of this like changing environment where there's increasing snow in colder temperatures as you go up. So the role that snow is going to play in kind of blocking the cold is going to depend on where you are on the mountain. So I'm trying to kind of tease apart what, what that means.

Saintsing:

So you've been going to the Sierras and kind of like checking out what's going on with these beetles.

Roberts:

Yeah. Yeah. So I work in the Eastern Sierra is right around Bishop between Bishop and Mammoth and there's populations of these beetles that have been monitored for a long time by, um, a couple of our collaborators, Nathan Rink and Elizabeth Doll Hoff. Yeah. So I have, I actually started working on this system around these beetles when I was in my undergrad since now, quite a while. And I actually started after I took that entomolgoy class that I mentioned earlier, like an yeah. Yeah. I mean, I, so yeah, I grew up in Fresno, which is like, you can see some mountains from it. Most days, you know, we would go up there sometimes like up to Yosemite when people come visit and stuff, but I'd never like gone back back in or gone in to the Eastern Sierra since I started working out there and it was, yeah, it was like experiencing it for the first time when I started doing that. So, uh, in a way it kind of was life changing. And then I guess the science part kind of was life changing as well. Yeah.

Saintsing:

Have you, uh, have you yourself, like experientially noticed changes in how much snow there's been out there over the time you've been going up to the Sierras?

Roberts:

Yeah, absolutely. Well, I guess the most obvious one, one or the most obvious change, I guess was 2012 to like 2000, maybe it's 2011 to 2014. There's like the biggest drought in California history. Um, that occurred in the time that I worked up there. So there's like this, this period of long minimal snow cover that occurred. And, um, I think one of the things that is most striking that it's noticed by going to these populations for a decade now is how many of them have just gone locally extinct. And like, there's, I remember my first year out working there, there's a site that we do a lot of like surveys where you just walk around counting needles for, for some time. And it was the first one that I ever, I think I counted like 310 minutes. And then, uh, this is 2009 was the first summer I worked out there and then 2020, there are no beetles at that site anymore. Like almost that entire mountain drainage is completely yeah. It's almost beetle free, which is, yeah. It's crazy to see change over. I mean, that's, that's a while, but like not really. So it has changed quite a bit since I started.

Saintsing:

Yeah. That's uh, you think, uh, that's step, or do you think that's a, um, kind of a product of like maybe short term variation to see so few beetles? Or do you think that's really like, I don't know, like, are they're not going to be those beetles there anymore?

Roberts:

Um, I think that this has happened before, maybe not to the same extent where, so they're, they're completely gone in that drainage except for one site, which I think they've constricted about the same amount before, um, in the late eighties, I believe, but, and they, they did come back. So I think as possible, but that's kind of relying on, I guess, something like a normal few normal years for them to be able to recover. And it doesn't seem, I mean, that's one of the biggest changes that have really been happening in the Sierra is, is that it just, it's extreme more often you see just extreme drought or extremely snowy ears. Yeah. So I think they could come back, but it's going to take a good few years of good weather, I guess. Yeah. Hopefully they come back.

Saintsing:

Okay. Well, so that's kind of a, a bummer, but, um, so

Roberts:

I'm going with that, but that's kind of why we try to study this stuff too. Right. If it's going to happen, you want to at least try to understand why it's happening so that you maybe, somebody can do something about it in the future or someplace else and yeah. Cause yeah, I mean, understanding what is happening is, is key and trying to help or mitigate it, I guess.

Saintsing:

So. Right. So then what are you doing to study it, to try to help or to help mitigate, um, what what's like actually doing, uh, experimental work to figure out more about this? Like, yeah. So

Roberts:

It's a pretty wide range of stuff. Like part of like part of what I do is collect beetles and then get them to enjoy dormancy and then simulate winter by, or like overwintering for them by burying them. And I, I try to do this or I do this in 2.2 areas, one that keeps snow off of it. Um, so they can like, there's a group of beetles experiencing a no snow winter. And then it is a separate group that is just out in the open. So it gets ambient snowfall. So, um, yeah, part of it is burying beetles alive and then coming back and checking on them. And then I try to do some aspect of like, like you can't do everything in the field. It's just not, it's difficult to get out there, especially when there is no. Um, so I do a lot of like mimicking conditions and lab incubators and like do some that's where I do like cold tolerance acids, which is, um, basically take a beetle, put it in a tube and then put it into a bath of ethylene glycol, some liquid that doesn't freeze until really low temperatures.

Roberts:

And it will just cool them down. You can kind of like precisely control what temperature they're experiencing. So yeah, that also doesn't yeah. The list of stuff I'm saying no burying beetles freezing beetles.

Saintsing:

It just sounds, it sounds weird to us because when you say three, a person frees the person that's, you know, it sounds like really bad for the person, but these, yeah. These are, this is part of their lives, right? Yeah,

Roberts:

Yeah, yeah. So they can, well, they can tolerate most of it. Like, I, I don't, it's not like seeking to, um, expose them to anything they wouldn't do their natural environment, but, um, I'm just trying to understand what events in the natural environment, how that impacts your survival. Yeah. So I, yeah, and not baring humans out there, but, um, and then I, I guess one of the other things that, that I think you and I have a lot of overlap in our interests then is, um, like energetic costs. And I'm really interested in energetic cost of winter. And what changing temperatures will mean because energy use rates in insects is determined, like temperature dependent. So changing temperature means you change, uh, energy use and, and overwintering organisms, can't just get up and just need, they're kind of operating off of like a limited amount of energy. So, um, and a lot of how I study this is by measuring respiration rates of beetles or, and this sounds, I think way cooler than it actually is in process, but like, I think you quantify CO2 production and beetles by using lasers. So sometimes I say like, I measure beetle breathes using lasers, which make this sound like a really cool, um, when really I just kind of inject some gas into a box and yeah. Um,

Saintsing:

Honestly injecting gas into a box sounds complicated too.

Roberts:

Okay. It can't be, it take, it took me awhile to figure out exactly how to do it. Right. But, um, yeah. Yeah. And that's, that's a big, big thing of what I've done is spent so long, just measuring respiration rates, which I think you can relate to that as well.

Saintsing:

Yeah. It's uh, you got, you got animals doing their thing and you got the machine doing, its the thing, you got you doing your thing and you know, occasionally, sometimes everything lines up and you get a good reading.

Roberts:

Yep. And at least with overwintering organisms, they don't have their own behaviors really. You know, they're kind of just like dormant. So it's, it's easier to work on them than it could be otherwise. Yeah. Which is helpful for a lot of stuff. And also it decreases the animal care you have to do because you kind of want to not disturb them when they're wintering. So yeah. So I guess this is like really like the main, main things of what I've done quantified I guess how much storage limit or in beetles as well, a big one that I've done to cause it, yeah,

Saintsing:

Because that's kind of what they use. They get, they store a bunch of fat when they're eating in the summer and then they use that during the winter. Yeah.

Roberts:

Yeah. And I think like you can get a pretty good idea of how much energy is currently being used by using respiration rates, but it really isn't, it's like acute what they're feeling at the moment or what the temperature is that they're in, where I'm looking at weather stores gives you kind of this summary of everything that I've experienced. So yeah, a lot of the work I've done kind of compares and tries to predict how much energy would be used based off of temperature and respiration rates. And then compare that to what we actually see with these lipid measurements.

Saintsing:

How's how, how have things gone? Have you, uh, found any like really cool results or uh, like w where are you at?

Roberts:

Yeah. Uh, so I guess the goal of trying to kind of predict what the energetic cost of winter is, goes back to this question of what snow does across elevation, like how it regulates that and regulates yeah. Stress, which in this case it's energy, stress or cold stress. And, um, yeah, so I I've, I've used weather or I guess micro climate data across elevation or Beatles over winter and kind of looked at energy use across elevation. And w what we see is that increasing well, as you go up in elevation and the energetic cost of winter is lower, which is weird because it's longer as well. But I think what a big thing of what people typically haven't thought about when they're thinking about snow cover is that it buffers not only from cold, but from warm as well. And these like spring warm temperatures, temperatures are also depleting energy source, um, before the deals are emerging. So at low elevation, we're having more of that, um, exposure to warmer temperatures. So that's kind of one of like sorta interesting findings.

Saintsing:

Yeah. And like, uh, oh, sorry. But just about that, you're kind of saying like, the Beatles might be going along well. And like, I got plenty, I got plenty of storage and then all of a sudden the warm weather, um, starts making them just go into overdrive then reserves plummet.

Roberts:

Yeah, exactly. Yeah. They're, I'm making, I'm so close to the finish line and then potentially that's where all of the cost is. So, um, I mean, just not make it, and I think that this is going to be particularly interesting. Oh. So if there's earlier snow melts and exposure to these warm temperatures, there's still like a spring has a lot of fluctuating, hot and cold too. So they're also been exposed to cold temperatures and warm temperatures. Um, so they get kind of the worst of both worlds with that too. And that is another thing with snow that is happening, I guess this is more like broad pattern, but snow melt is starting earlier and then onset of snowfall and starting later due. So this season just kind of shrinking. Yeah. So, yeah, that's an interesting finding for that reason. And then I, I didn't mention anything about the difference between when snow is, I mean in a snow year versus a dry year, but, um, in snow years, the energetic cost is just overall higher across the elevation.

Roberts:

So it's kind of what we had predicted. Um, but at high elevations, they seem to be this site where they it's just so similar. There's just always a little bit of snow. And I think this kind of says that, like this may be a good site that is resistant to decreasing still too. So they may be able to move up in elevation if conditions become difficult, otherwise, which is a pattern then we're seeing otherwise inactive seasons, um, a bit more so like ranges of butterflies and see them move up, um, you know, elevation and plants move up in elevation response to increasing warm temperatures, but there may be this benefit in winter as well.

Saintsing:

So you're going to see more and more things just kind of restricted to the top of the mountain.

Roberts:

Yep. And at some point you've run out a mountain and you can keep going up too. So there's kind of a limit this why mountains are interesting besides getting to go hike around mountains, um, as a job basically. But yeah, they're, they're interesting because there is so much change over such a short scale, and then they eventually just kind of stopped.

Saintsing:

Does uh, has doing fieldwork changed how you experience? I dunno, the outdoors when you're not doing field work. Yeah. Yeah.

Roberts:

Well, I, it's hard to tell, I guess, what is yield work and what it is like biology or being a scientist for me, I guess, um, because the kind of started at the same time basically. And, um, so yeah, like my initial answer was going to be, you know, going someplace, I like will always look on plants or bugs and like, I don't know, just kind of notice the environment, environmental conditions, just weird stuff like that, that I probably wouldn't have if I didn't do field work. And then also didn't study biology as well. So, um, yeah, I mean, I guess it kind of changes the way you see the world in general. Right. But I also don't know what changed from then, but also a lot of stuff has changed since I was pre science. So, um, who knows what's responsible for what?

Saintsing:

Well, this has been a lot of fun, but I think, uh, we are running out of time on the interview, but yeah. Do you have anything that you want to leave the audience with before we go?

Roberts:

We're faced with this existential crisis in terms of climate change. Right. And there's a lot of negative emotions, I think that are associated with that. And I, I think it's a, it's easy to get kind of get really far into that. And I guess what I'm trying to get at is is that, Hey, you don't have to be a PhD student to, to notice a bug in the environment or yeah. It's just, um, it all fits together in such a cool way. It's I think it's really important to kind of get out and go experience those environments and things are changing, but they still are how they are now.

Saintsing:

Yeah. Today I've been speaking to Kevin Roberts from the department of integrative biology. We've talked about his work on beetles and the Sierras and how they survive the winter. Thanks so much for being on the show, Kevin.

Roberts:

Yeah. Thanks for having me here. It's been great.

Saintsing:

Tune in, in two weeks for the next episode of the graduate.

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