31– The anthropause diet, with the iguana researching Dr. Susannah French

August 21, 2020 Utah State University Office of Research Episode 31
31– The anthropause diet, with the iguana researching Dr. Susannah French
31– The anthropause diet, with the iguana researching Dr. Susannah French
Aug 21, 2020 Episode 31
Utah State University Office of Research
Tourists love feeding the Northern Bahamian Rock Iguana. These herbivores are used to eating grapes and other human foods, instead of the local plants. But what happens when the tourists stop coming. 

Show Notes Transcript
Tourists love feeding the Northern Bahamian Rock Iguana. These herbivores are used to eating grapes and other human foods, instead of the local plants. But what happens when the tourists stop coming. 

Wyatt: [00:00:00] Oh, my gosh, eating healthy during this pandemic is the worst, right? I mean, working at home, like I'm just so close to my fridge, but for some organisms eating healthy, this pandemic has been their only option because they're iguanas and they live in The Bahamas and there aren't tourists showing up with fistfuls of sugary grapes for them to eat.

[00:00:29] So today on instead I'm interviewing a USU researcher who is studying what happens when the humans stop showing up. In this episode, you're going to hear from USU Dr. Susanna French. You'll learn how she catches and tags iguanas that can weigh up to 10 kilograms or 22 pounds, which is like a sack of sugar.

[00:00:51] Or a beagle, Dr. French will also tell us what this Guana poop should look like and what it does look like when there's too many tourists around I'm Wyatt Triber, and you could be putting a padlock on your fridge right now, but you are listening to this. Instead. Two things before we get started, number one is.

[00:01:16] Follow instead, podcast on Instagram and tell your friends about it. Number two is go back and listen to episode 13. If you haven't yet. I talked to a USU political science researcher, Damon Cannes. And he filled me in on why you taught turn to mail in voting long before this pandemic happened. That was episode 13.

[00:01:37] Now we're going on episode 31. 

[00:01:40] Susannah French: [00:01:40] Um, so I'm Susanna French. I I'm a professor of biology and the ecology center. Um, and I'm also the associate department head in biology as well. Recently 

[00:01:51] Wyatt: [00:01:51] you were featured in science magazine and a term they used in the article was anthro pause. Can you explain what that word means in how they're using it?

[00:02:01] Susannah French: [00:02:01] Um, in this case, it is basically the cessation or temporary removal of. Human impact in different areas. Um, so anthropogenic disturbance is something we study in our lab and, um, we do a lot of work on. And so this anthropology is basically the stopping of those anthropogenic or human induced impacts. 

[00:02:24] Wyatt: [00:02:24] Um, so obviously this has kind of been caused by COVID 19 people not participating or being.

[00:02:32] In those locations as much. Has this been an interesting moment for you to do your research or is it like ruined your research in ways? I guess? 

[00:02:44] Susannah French: [00:02:44] Well, it's ruined parts of it and opened up new opportunities. No. It's definitely unique, a unique time in history and especially for somebody who studies anthropogenic disturbance and how that affects wildlife.

[00:02:55] It's brought up some new challenges, but opened some new doors as well. You rarely in nature can actually. Control things enough to remove the disturbance that you're studying. And so this is really a new sort of natural experiments that we can, um, obviously it's a horrible, uh, travesty, but it's also a unique, scientific opportunity that we may never have again, to understand what impact, uh, humans are having on the wildlife.

[00:03:21] But with them not being 

[00:03:23] Wyatt: [00:03:23] there. I want to back up just a second, I guess, anthropogenic. So that's the same brute is anthropology and that's like study of humans. Tell me what anthropogenic means, but that word means in the context of your research. 

[00:03:36] Susannah French: [00:03:36] So we're looking, it's basically human changes or human effects.

[00:03:41] So on a very general level, and you can take that and look at different parts of it and different impacts, but yeah, on a very broad level, just think human induced . 

[00:03:52] Wyatt: [00:03:52] Okay, cool. Cool. So you're studying these iguanas and The Bahamas. What drew you to them as a research subject? 

[00:04:00] Susannah French: [00:04:00] So I've been working for many years, actually before The Bahamas, I was working in the Galapagos islands.

[00:04:06] Um, also looking at ecotourism impacts on iguanas there and was contacted by a researcher from Shedd aquarium. Who's been working for 20 years in The Bahamas and they have not just. I wouldn't call it ecotourism, but even greater sort of tourist interaction where people pay money to go visit these animals and just seeing them as, not enough, they want to feed them.

[00:04:28] So these animals are actually not just behaviourally conditioned, they're totally responding. And, um, you know, you hear the boat motors off in the distance coming from Nassau, and these iguanas will run out to the beach. So it's, it's changing the way they live is changing the way they behave. And it's also changing the way they interact with one another.

[00:04:47] Wyatt: [00:04:47] What are you able to learn from them? 

[00:04:50] Susannah French: [00:04:50] There's sort of two, two sides to this. Um, these animals are highly endangered species and, um, they're only found on a few islands. And so all of these pressures and things and, and, and current hurricanes, recent hurricanes, they have, they're really high concern. So conservation and maintaining healthy populations is really important.

[00:05:09] For, you know, promoting species diversity and for the islands themselves, they're the, the major vertebrate on the Island, responsible for moving seeds around and keeping the ecosystem going understanding and keeping them healthy as is really important for conservation. But it's also important for a sustainable tourism ministry for The Bahamas, which is their main livelihood.

[00:05:29] And we don't want to shut it down. We just want to understand. What it means and how we can keep it sustainable for them. Yeah. So that's, that's that's side one, I guess that's the conservation aspect of it, which is really important. The other side of it is sort of this unique natural experiment because we have these multiple populations on different islands that are really in close proximity.

[00:05:50] So the environment is the same. Everything is really similar. The differences this population sees people up to hundreds of people a day gets fed all these crazy. You know, non-native food items and the populations next door don't. And so it's the sort of natural experiment that's been going and increasing over time.

[00:06:10] And so we can understand how resource differences or increased competition because these animals congregate in these unnaturally high dense groups. Um, all of these factors are actually impacting wildlife, but we can do it in nature, um, where they act natural. I should say, you know, when you bring animals into the lab and.

[00:06:29] They don't, there's a lot of things that, um, you can control far and are great to do in a lab, but you don't get natural responses and physiology and behavior. 

[00:06:39] Wyatt: [00:06:39] Yeah. So before the pandemic, how were these two, um, populations of a guanos like behaving differently or participating differently in their environment?

[00:06:51] Susannah French: [00:06:51] Right. So I should say we're actually, we've been studying about eight populations over the whole region. It's interesting, because then we're getting these replicates. Of tourism and non tourism throughout the islands. So we can see an interesting things. We're seeing similar responses in both. So we really do believe that tourism is driving.

[00:07:08] We're seeing higher densities of animals, congregating. I think these islands, some of them are reaching their carrying capacity. Some of them are very small islands and there's way more animals than you should see there, which some people may say, well, that's a really good thing, but if you remove all that extra food, like it's happening now.

[00:07:25] What are they going to eat? So coming into this before I even started, we already knew from long-term monitoring from one of my collaborators at Earlham college, John Iverson, he showed that, um, over 40 years of sampling these populations and studying them that he saw reduced survival in these tourists populations relative to the adjacent Island.

[00:07:45] And we knew from the, my collaborator, Chuck Knapp at shed, that we had altered blood chemistry. So we knew things were going on. We knew they weren't behaving normally. I came into the story to add the physiology to say, okay, well let's what is causing these changes? You know, what's, what's happening behind the scenes.

[00:08:01] Wyatt: [00:08:01] Yeah. By reduced survival. Do you mean, um, individuals aren't living as long or the whole group isn't living as successfully? 

[00:08:10] Susannah French: [00:08:10] They're, they're not living as long overall at a, as a, at a population level. There's obviously variation within that. But yeah, overall, if you look at, uh, survival across different age groups, you're seeing not as many animals surviving as many years, and it's significant because this is a really long list.

[00:08:25] Species. We know that they can live at least 40 years and we know that they take a long time to reach maturity and reproduce. So it's important to know these things. Now we, you know, generations from now, we may not be able to catch up if there are, if there are negative impacts, 

[00:08:39] Wyatt: [00:08:39] but there are. More of them in these human fed groups 

[00:08:45] Susannah French: [00:08:45] currently, what I'm helping to look at.

[00:08:48] I mean, and part of what makes this study so interesting and valuable is this rich, um, ecology, demography, population monitoring that was already present that I came into. And then we're adding, um, metrics, looking at these animals immune system, looking at the reproductive system and trying to link what is actually going on behind the scenes.

[00:09:08] And so we're finding. We're finding like you would expect, um, altered, uh, blood glucose, these animals get grapes every day. It's a definitely a high sugar diet that's, um, leading to what we've actually shown would be called a diabetic response in humans. Um, So what that means in a lizard, I'm not going to, I'm not gonna go that far, but we're seeing changes in, um, the production or the pathways for the production of free radicals, which we know can affect survival and also cause tissue damage.

[00:09:40] We're seeing changes in these animals, uh, energy metabolites in their blood. Like you would expect the animals to get fed, have tons of them, but they also show differences in hormones that regulate those. So there's a bunch of different things going on at the same time. And. Now with this so-called anthropods we can look at what happens when that goes 

[00:09:59] Wyatt: [00:09:59] away.

[00:09:59] Like a guest, if they're kind of a Keystone species, what were they eating before? All of this human food and how have those species changed? Because. 

[00:10:09] Susannah French: [00:10:09] Okay, great. No, that's a great point. So that's something we've actually, we have this, this is a big collaborative group and we're looking at, um, there's actually a Dr.

[00:10:18] Charles quit at the university of Tennessee is helping to look at seed dispersal and there's potential also for effects on seed germination. So these animals are herbivores. They are there, they will occasionally eat like a little nesting seabird egg or something like that, but they're primarily herbivores and yeah.

[00:10:34] So naturally they'll go around. We'll eat a bunch of leaves. There are a fruiting plants on the Island, but it's not like a regular year round thing. Um, and so like, yeah, you'll see a normal Guana feces pellet. It actually looks, we call it says, say it looks like a Cuban cigar. Um, and then th then these tourists come in and feed them, uh, a bunch of grapes, a lot of fruit, it has changed.

[00:10:56] I will say it was actually gotten. Better. It used to be meat bread, although that does still show up sometimes. But with the help of some of my colleagues, they've really moved towards feeding, at least fruits and vegetables and a more varied diet, which is better, but it's still, usually they're getting a lot more fruit and things that they wouldn't naturally get regularly.

[00:11:15] So now we're seeing the equivalent of the Guana diarrhea everywhere, which is just. Wonderful. Oh, and so part of this, that's been really interesting as I'm collaborating with, um, Dr. Karen  in the biology department. And she's, she's helping us to look at these animals, gut, microbial community, and how that is feeding back and affecting their health as well.

[00:11:37] So there's so many parts to that, but I could also affect seed germination and the ability of these animals to deposit, you know, viable seeds that will keep the communities going. 

[00:11:47] Wyatt: [00:11:47] Yeah. So now that there isn't tourism and they're not getting that human cost food, have you been able to study what's happening with them or are you waiting until you can get down there?

[00:11:56] We're 

[00:11:56] Susannah French: [00:11:56] trying to get down there. We, um, we definitely have, um, we've been talking to local, local boaters and there, there are some people that inhabit local islands, so there are still some people that are visiting, but it's. Local date boaters. We're not getting these groups of hundreds of people descending every morning, like we normally do so, but no, we don't really, we don't have a really good understanding.

[00:12:18] So as soon as we can get there, you know, we're, we're, we're trying. 

[00:12:22] Wyatt: [00:12:22] Yeah. Do you have any. Hypothesis of what's happening to 

[00:12:26] Susannah French: [00:12:26] them. The two sort of sides to this one, let's just say there, the population is not way over, over. It's not way over populated. It's not too abundant. Then you would assume that they would revert back to more natural diet.

[00:12:41] And if that happens, he would. You would expect that their physiology, their gut microbial community would shift back to look more like those natural populations. Um, and especially given the long life of these animals, you know, you could see that shift back. Um, there could be some, you know, um, epigenetic effects that maybe will not go away.

[00:13:01] Um, so that, that would be really interesting to understand, um, especially in some of the younger animals. Um, however, if these animals have overpopulated these islands and there is not enough food available to sustain them, they're congregating in large groups, we would expect to see reduce body condition.

[00:13:19] And we could see actually the situation can go more from normal or in a totally different direction where there. Condition is being reduced. They're they're starving. They're they don't, you know, um, so different effects on their kids. 

[00:13:31] Wyatt: [00:13:31] Yeah. Yeah. I know that when my diet changes, like what I eat, like if I buy like a giant box of like Kashi cereal or something, like there's a lot of intestinal distress that happens, um, And I'm guessing as a mammal, like that might be easier for me to handle than a lizard.

[00:13:49] Would, do you think that they could, what kind of suffering or survivability problems that happen when you are forced to eat healthier? 

[00:13:59] Susannah French: [00:13:59] Well, it's a really, no, it's a really, really good question. Um, Yeah. I mean, that's something we're trying to understand better. And these animals, um, I mean, yeah, humans and mammals, they've documented how much diet can shift.

[00:14:10] And we've actually shown, we do know that the microbial communities are different according to the amount of tourism there. So that's something we definitely want to follow up on. And we know that a lot of these little, these little critters, these little microbes are linked to. Health and stress in humans, what that means in a Guana.

[00:14:29] And a lot of them actually, I should say are unidentified because it's, you know, we're talking about a huge, huge microbial community. Um, that's what we're trying to focus on more. And I should say the other part of this study that. Is, um, really important is we're actually doing, um, controlled lab studies using a non-injured, but not too distantly related iguana in the lab because it's hard in the field to test directionality.

[00:14:55] So those studies are ongoing as well. That will help us say, okay, well, is it the microbes? Is it the diet or is it the interaction of the two, you know, or other factors? I guess, 

[00:15:06] Wyatt: [00:15:06] like, you're probably waiting for a lot of things to be able to get down there, but like when you get down there, what are the first things that you're going to be doing or 

[00:15:13] Susannah French: [00:15:13] want to do?

[00:15:14] Hopefully it depends. If it's, if it's earlier in the fall, we avoid hurricanes that's step number one. And then step number two is, um, we're basically going to go survey and sample the islands, um, remeasure, all these animals we've got really, um, we've got a lot of marked individuals on these islands. We can compare, um, from previous sampling trips.

[00:15:35] We're going to re sample their blood and their microbial communities. Most of that, we may actually measure on the boat. We haven't decided yet. It depends on export situation, but we will. Um, yeah, we'll be, we'll be analyzing, um, a bunch of physiological measures that we've done before. And the great, great thing about these animals is especially at the tourist sites, they are so dense that, I mean, we'll go down in 10 days and we'll sample a thousand iguanas across all of these sites.

[00:16:02] And, um, And it's, you know? Um, yeah, so that, that's our main, our main goal and avoiding hurricane. 

[00:16:10] Wyatt: [00:16:10] Yeah. How do you catch one of these iguanas? Like, can you just like go sneak up on it and pick it up, or 

[00:16:16] Susannah French: [00:16:16] so just to explain the difference you go to one of the sites where people don't visit and the reason I should say the reason they're not visited is they don't have a nice, very beautiful Sandy landing beach.

[00:16:27] We have to jump from a moving boat onto craggy rocks, and then, uh, Get on the, get on the Island, but that means other people don't go there. And when you get on those islands, you don't see an animal. So it's really challenging. You have to sneak up on it. You have to, um, and we use what's called like a lasso on the end of a, on the end of a pole to just restrain it.

[00:16:47] And then somebody jumps on it carefully, but jumps on it and grabs it. And so we don't pick it up with the lasso, but you just restrain it. Or we have these big fishing nets that you use again, just to. Hold them in place until somebody can get on them and handle them carefully to get them up. Um, what size 

[00:17:04] Wyatt: [00:17:04] are these?

[00:17:04] Um, 

[00:17:06] Susannah French: [00:17:06] so, so the ones, and it depends the ones, uh, some of the Southern iguanas, um, on the tourist sites. I mean, they can, they can be huge. They can be 10 kilograms almost. And so, I mean their body for body to tail, they can be, you know, some of them I'm not comfortable restraining myself and usually I am, but yeah, I mean, they'll bust through our nets.

[00:17:26] And we have to be really careful and some of them require two or three people to hold them. Um, and you know, process them really quickly and get them back. So we're not stressing them out too much, but, um, yeah, but on the tour sites, these gigantic animals just walk up to you and you could literally just grab them and pick them up.

[00:17:41] So. That's the difference. However, some of the longest studied sites, um, they know us and they know that we're not tourists because we have like good sun protection. We're not, you know, drinking beer on a boat in a bikini. So they will, they will. Yeah. If we were doing that, they'd probably be less scared of us, but because we have like sun hats and sun shirts and stuff, they're like, yeah, we know you guys.

[00:18:06] We're 

[00:18:06] Wyatt: [00:18:06] not. So do they, are they like running for him or trying to evade you before then? Oh, that's funny. You might have to like, look like a tourist. At some point, 

[00:18:17] Susannah French: [00:18:17] well, sometimes because of how hot it is, you have to take a little break at noon and get in the water and then they come back out. Cause they, you start acting like tourists again.

[00:18:24] So it is actually a good strategy. Yeah. Wow. 

[00:18:27] Wyatt: [00:18:27] Wow. That's so crazy that they can. Remember you, um, how were they Mark? How do you Mark them? 

[00:18:34] Susannah French: [00:18:34] Like you would a dog or a cat. They have these little, um, passive, uh, transmitters that go, you just sort of inject under the skin with a sterile little sterile syringe.

[00:18:44] And, um, yeah, so they're scanned. So you, you have to catch them to know who they are because you have to be up close with the reader, but then we just scan them and we can pull up all the records and see who they are, see how they've grown and, you know, collect new data, moving forward. 

[00:18:57] Wyatt: [00:18:57] Are they named, are they just numbered?

[00:18:59] Like, 

[00:19:00] Susannah French: [00:19:00] um, it depends on the Island. There is, there is, for example, my collaborator, John has one female who he catches almost every year named Rosie, but for the majority of them, no, but that's because she just gets really pretty and red when she's yeah. When she's yoking up eggs. So 

[00:19:16] Wyatt: [00:19:16] cute, cute. Uh, like the anthropods thing happening down in The Bahamas.

[00:19:21] Is there anything here in Utah that might be seeing similar or different effects? I mean, there is a lot more outdoor recreation happening here right now, so we might be seeing the opposite, right?

[00:19:31] Susannah French: [00:19:31] No, I completely, yeah, no, I completely agree. I mean, I think. Some of those effects may have been seen earlier when people were not going out.

[00:19:39] You know, you think about St. George, you think about salt Lake city and some of these parks where you normally have large numbers of people recreating. I think some of these urban. Natural slash habitats. I think there, I mean, I guess I would have to know more about what the visitation is like now, but I'm sure early on you did see differences in terms of maybe animals being less, um, less wary.

[00:20:02] Um, one thing that does though happen in these urban settings, um, at least from we study lizards in St. George, Utah, these tiny little sidebar lizards. And they're habituated to seeing people regularly. So, you know, um, but it may change their behavior. And maybe when people come back, they get more, you know, more shy, what have you, or it may allow other animals that normally avoid people to be more active at times when people would normally be around, which it sounds like is happening with like wild boar in Europe and, you know, birds elsewhere.

[00:20:33] So I think, I think that's a very real policy. Uh, possibility here is, do we 

[00:20:37] Wyatt: [00:20:37] have any like feeding the animals problems here in Utah that you're aware of every 

[00:20:42] Susannah French: [00:20:42] national park I've ever been up? People feed the chipmunks. I'm sure I've seen it here. I've seen it, you know, our ground squirrels, um, it's bigger issue and you know, like Rocky mountain and in Yellowstone and Teton, there's more of them there, but.

[00:20:57] Yeah, that it happens. At least they're not endangered species, but you know, there's something about that interaction where there is some, it's a direct interaction. It's not just seeing them. And I don't know, apparently it resonates with a lot of people all over the world because people want to do it everywhere you go.

[00:21:13] I would ask people not to. There's pretty good. We'll sit there. And actually once they've been fed enough times, they're conditioned probably for the rest of their life. Anyways. So they'll still come out and you can see them. And even 

[00:21:23] Wyatt: [00:21:23] just like the one or two times I've been back East, just like seeing how less scared of people like the animals are, is weird to me.

[00:21:31] I'm like, what is this chick Munk doing? Like within five feet of me, this is not normal. It should be so much farther away. 

[00:21:36] Susannah French: [00:21:36] Yes, exactly. 

[00:21:38] Wyatt: [00:21:38] Exactly. Um, and then why is it important that we study these Guana? And 

[00:21:45] Susannah French: [00:21:45] that's a really important point. I mean, it's. They, um, there are some things that make actually understanding just basic animal physiology easier.

[00:21:53] And I will say they have the exact same hormones are very similar hormones. Do we have as people? So understanding the way that these. Physiological systems interact in a free-living animal is actually very, very important. Even for ourselves. The mouse models are great and you can isolate specific mechanisms, but we're not all identical.

[00:22:12] And, and we respond to different changes in our environment. And so there's a lot of insight you can get from natural wildlife. There's also the conservation aspect, you know, we're. We're doing enough to this planet right now, we should conserve what we can, which I'm really interested in. But yeah, from a basic science perspective, I mean, um, they have the same hormones.

[00:22:31] They have a lot of the similar immunological pathways and they also don't waste a whole bunch of energy on. Thermal regulation or at least internally producing, you know, their, their temperature through metabolism. And so it actually simplifies the sort of overall picture and makes them a really good model for physiology.

[00:22:49] Many of them are territorial. And so you can find them in the same locations throughout their entire life. And so that's really beneficial, whereas mammals, not that they aren't, but the way to catch them a lot of times is either through a trap or netting or something. And it takes a really long time to catch them.

[00:23:05] And. Get your samples. And for us, we get our samples within one to two minutes. So we can actually look at what the animal's physiology looks like before us handling it. Messes it up. 

[00:23:17] Wyatt: [00:23:17] How long do you think that there will be any lasting effects from this anthropods on these iguanas? Or do you think it will be like, Oh, they had a little timeout from humans, but everything's back to how it was 

[00:23:27] Susannah French: [00:23:27] before.

[00:23:28] Yeah, no, the good thing they have going for them as their metabolism is relatively slower than other organisms. So I think in some ways, It's going to be, they have a, like a better likelihood of recovering, but I think it could be a long-term impact, especially because tourism, um, is not going to be picking up there anytime soon.

[00:23:45] You know, there's bands right now while there's not bands, there's a lot of stipulations for people from the U S to go there and we're one of their primary sources of tourism. So, yeah. So yeah, I think it's possible. I think it will take a long time to recover and I think we could see depths and populations depending on if the.

[00:24:02] The food shortage is severe enough. We could see drop in actual population number for awhile. 

[00:24:09] Wyatt: [00:24:09] I think that older individuals will have an advantage because they will have more experience knowing where to get food. Or do you think that it will be a free for 

[00:24:19] Susannah French: [00:24:19] all? Yeah, they have higher energetic requirements too when they're old.

[00:24:22] So it's, or they get bigger, you know? And so once they get to a certain point versus these little guys, but, um, yeah. Maybe, but probably more that they'll, out-compete others for the few sources that are there. Um, yeah. And males are more aggressive than females on these sites. So, and that's the other thing.

[00:24:40] This anthropods happened right in the middle of their reproductive season. So we're going to be looking at recruitment. How are these females? I mean, they basically, they got their food cutoff, right? When they were trying to yoke up eggs, maybe they had enough. Internal energy stores. That they'll be fine, but it'll be really interesting to see how that's affecting nesting and reproductive success for this year.

[00:25:01] Wyatt: [00:25:01] I'm pulling for these iguanas and I'm excited for Suzannah to get down there and start understanding what's happening to them during their anthro pause, please subscribe to instead in your podcast feed and go follow at instead podcast on Instagram. And don't forget to listen to episode 13. About pioneering male in elections in Utah.

[00:25:25] Thank you for listening to this episode of instead, instead is produced by me, Wyatt and Nick Vasquez as part of our work in the office of research at Utah state university.