Episode 3: Extinction and its consequences
Dragonfly team members and instructors Ramana Callan, Kendra Cipollini, and Kevin Matteson discuss the following required readings for this discussion as well as their personal feelings about extinctions.
We start off discussing extinct and endangered species including American Chestnut (functionally extinct), the Passenger Pigeon, and the Thylacine (Tasmanian Wolf; see this video for footage of last known thylacine before it went extinct). Enjoy!
“I always love the name of the Metatron study (long-term fragmentation study) in France… of course, it makes me think of Transformers.” -Kevin
The title of this discussion was Extinction and its Consequences. The first two articles are really about Extinction and its Causes (Brook et al. 2008 and Haddad et al. 2015) and this last one is really about consequences (referring to Brashares et al. 2014 article about social conflict).” – Ramana
“Lag times totally freak me out…” -Kevin
“That was the perfect segue … speaking of bleak! We know all about all these things that are causing extinctions. We know the four big players … The “evil quartet.” (talking about Brook et al. article) – Kendra
“2+2 = 6” – Kendra (When referring to non-additive effects habitat loss, fragmentation, climate change and more)
“Acorns and beechnuts have taken over that ecological role (American Chestnut) but they don’t produce as consistent food so the wildlife is different because you had this constant massive crop of nuts every year. So, yeah, I would have liked to see mature, old-growth American Chestnut dominated forest.” Ramana (talking about functionally extinct American Chestnut)
- Brook, B. W., Sodhi, N. S., & Bradshaw, C. J. (2008). Synergies among extinction drivers under global change. Trends in Ecology & Evolution, 23(8), 453-460.
- Brashares, J. S., Abrahms, B., Fiorella, K. J., Golden, C. D., Hojnowski, C. E., Marsh, R. A., & … Withey, L. (2014). Wildlife decline and social conflict. Science, 345(6195), 376. doi:10.1126/science.1256734
- Haddad, N. M., Brudvig, L. A., Clobert, J., Davies, K. F., Gonzalez, A., Holt, R. D., … & Cook, W. M. (2015). Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances, 1(2), e1500052.
TRANSCRIPT OF AUDIO
Hello, folks. It’s Kevin Matteson again. Thanks so much for joining us for our third podcast about extinction and its consequences for the issues in biodiversity class. You know the drill at this point. We have three different instructors discussing the papers that were assigned for this discussion, and the goal here is to just reach you all wherever you are in a different format than the standard written word in the workshops. So this is a compliment to what you’re doing in the course sections. One of the cool things I think that’s really neat about this is that we have multiple sections of issues in biodiversity, as most of you know, with over 200 students currently in the class and about 10 instructors. So this podcast is a way that we can actually be connecting with the entire group. Even though in your actual sections you’re in, you’re just interacting with those students and that instructor. So we are reaching all the instructors for issues in biodiversity.
We have Shafkat and Katie Feilen will be joining next for discussion 4, and then Jeannie Miller Martin, and Ramana Callan will be joining for our final discussion of the fifth discussion in the course. So again, drop a note if you are enjoying this, or have comments, or going the content, or clarifications, or anything you want to say. We actually are going to start reading these comments at the end of the podcast for each episode, if you’re okay with that. [LAUGHTER] So feel free to email me at matteskc, M-A-T-T-E-S-K-C, @miamioh.edu, or you can give me a call and you can leave a voicemail on my office line. If you’re okay with it, we will go ahead and add that to the podcast for the future. So again, if you just have a thought that was spurred on, or how you’re listening to this, where you’re listening to this, we would love to hear your ideas. We know you’re all busy, but the feedback is fun and it helps us build community here. So you can give me a call at 513-529-0837 and leave a message or email me your thoughts and comments. All right. I think that’s it for now. Enjoy the discussion.
Beginning of Conversation
All right. Welcome. This is Kevin Matteson in our third podcast on discussion 3 for issues in biodiversity. We’re talking about extinctions and its consequences. This time we have Ramana Callan here, who’s one of our visiting Assistant Professors. You can say, hi, Rama. >> Hello. >> We also have Kendra Cipollini, who’s an Adjunct Professor, and actually lives here in Yellow Springs, Ohio, where I live as well. >> Hello. >> [LAUGHTER] All right. Cool.
So three of us are talking via Skype here, and I’m going to have a conversation about the three articles required readings for this particular discussion. But I thought we’d start off by sharing a little bit about a species that has gone extinct in relatively recent human history. So Rama, do you want to start off with yours? >> Yeah. So I’m Rama Callan and I teach a couple of sections of issues in biodiversity this semester. I definitely thought about animals first and then I settled on American chestnut would be something I’d really like to have seen. They’re not technically extinct. They’re functionally extinct. So you will find seedlings out in the forest, but they don’t grow to maturity because of the chestnut blight. So I think it’s really hard for us to imagine what these forests were like. There were four billion American chestnut from Southern Maine all the way to Mississippi, and they were the dominant tree species there. It could be 100 feet tall and 10 feet in diameter, and to have seen those mature forests, I would’ve loved to have been around during those times. When I go for a hike in the woods, I find the three-foot diameter weight pi and get really excited and these trees are just so massive. Then they produce so much food for wildlife and humans and consistent food crops every year. So acorns and beech nuts have taken over that ecological role, but they don’t produce consistent food. So I think the wildlife is probably a lot more abundant and different as well just because you have this constant massive crop of nuts every year. So yeah, I would have liked to have seen mature old growths American chestnut dominated forests. >> Cool. Well, cool and not cool, I guess I should say. [LAUGHTER] Motive for much of this discussion actually. But Kendra, I feel like you as botanist might know something about American chestnut or where to find it. Have you ever seen any mature trees in your life that you know of? >> I have seen some flowering trees. So the interesting thing about chestnut, is you find them in the field, that root-stock is there. So they died back from chestnut blight, but you still have the roots there. So they will sprout back and then the chestnut blight will kill them once they usually get to a certain diameter, and they don’t get past that. But sometimes some get through and you’ll see some flower. I don’t think that I’ve ever seen any fruit in the field, certainly, but we have seen some chestnut. My husband, who is a biologist too, looks for chestnut all the time. His brother, who’s also a biologist, actually does some work trying to breed in genes from Chinese chestnut into American chestnut that have resistance to chestnut blight. So for a long time, there was a stand of chestnut in Wisconsin, I believe, that did not have chestnut blight and that’s because it was a plantation that was planted and the disease did not spread there. That plantation has been wiped out. But it was an interesting anomaly. So people could still see chestnuts not quite in its natural habitat. But the other interesting thing about chestnuts too, is that they were a huge food source for a bunch of different animals. There were specialists moths and specialists things that fed on them. They’re huge food-based for the whole ecosystem and yet they’re gone now. So it’s mind-boggling. >> Yeah, definitely. >> That actually, it gets into the cascades and the extinction chains that are discussed in some of these articles, but Kendra, what was your species? >> So the species that I landed on was the passenger pigeon, partly because it’s an interesting story, but it also has some local connections. The very last passenger pigeon died in the Cincinnati’s zoo here, just about an hour from where we live, and there’s a little monument to her. Her name was Martha. She was lonely looking for a mate, and they couldn’t find its [OVERLAPPING] male mate to mate with her. She died alone in 1914 wishing for more eggs. But it’s an interesting story because the passenger pigeon was such a bird that was in huge abundance. The estimate, six billion birds, a lot of birds. The interesting thing about them was that they were nomadic. They were fruit feeders. They’re also really good fliers, interestingly. They could fly up to 60 miles an hour. So they were swift fliers, fruit feeders that went nomadically around from where trees were fruiting or plants were fruiting, they swoop in, eat all the fruit, hang out, and then move on to the next place. So there’d be days and days, a longtime, months, years where you wouldn’t see the passenger pigeon, and then all of a sudden, just one day it would come. Some of the early accounts of the species were, when these flocks come, they’re like 15 miles long and three miles wide, and they’re black in the sky and they were in such abundance. They’d land and roost at night. People would go and swing bats and swing them out of the trees and eat them and over harvest them. They were so abundant. It was one of these ones that people thought would never go extinct. In the 1800 sometime maybe, I don’t know, maybe about 1820, I don’t remember the exact date, but some people noticed, “Hey, maybe the passenger pigeons can’t really take all this hunting. Maybe the Ohio legislature should do something about it and provides the protection.” The lawmakers came back and they’re like, “No, there’s so many of them, we could never make them go extinct.” So they had some thought about protecting them, never did anything, and now they’re gone. So it’s amazing too. Again, just like the chestnut, these huge, dramatic species that was super abundant all of a sudden just went extinct. >> Yeah. I was actually thinking about passenger pigeons recently, [LAUGHTER] because I was talking to my son about extinct species on the way to school, and I had heard that they estimate, they made up like 25 percent of the abundance of all birds in North America at one point. So I used to wonder how could be possible that humans could hunt something out like that. The analogy that helped me understand that was thinking about Bison and how numerically abundant they were in North America until these trains moving out West with people that would just shoot from the trains partially to clear the lines to some degree, but also to perhaps erode the social cultural capital of Native Americans for whatever reasons. But if those Bison could be brought down to whatever it was, I think less than a 100 individuals left at one point, I guess, yeah, the passenger pigeons as well, and especially when these species are not adapted to humans as predators or humans as predators with guns in that case, seems we can be very damaging. [LAUGHTER] >> Yeah, and it comes down to too biology too of the organisms as well. So there’s various vulnerabilities. One vulnerability of the passenger pigeon is that it was very social and were in these huge flock. So they were very easily targeted and they were naive to predators as well, but just such large amounts you could easily get them all in one place. >> Yeah, it makes me think of monarchs too. Monarchs are one of the top 10 most abundant butterfly species in much of North America, which is surprising to people because they’re used to hearing about how monarchs are threatened. But they are threatened because they have these overwintering sites where they congregate that are facing a lot of habitat destruction in certain areas. So that tendency, even if you’re numerically abundant, to all go to one place and make you very vulnerable to those things can still keep you in a threatened state. Cool, not cool, I should say again. >> [LAUGHTER] Cool, not cool. >> Cool, not cool. The species also thinking about was the thylacine or the Tasmanian wolf, or sometimes called the Tasmanian tiger, which was a marsupial that lived in Australia and Tasmania, and was wiped out sometime in the 20th century, I think around the 1930s, they think the last individual died. It’s an interesting example of synergies of things affecting it, and may have been some disease due to introduced dogs, and may have also been overhunting and persecution by people who considered it a threat to their livestock. That might have been also over the course of thousands of years, not just over the last few 100 years, that they were declining due to that. So a few things going on with it, but I just think it would have been so amazing to see a marsupial predator of that size. I don’t think there’s any other examples that I can think of that fill that unique niche evolutionarily so. >> Have you seen the YouTube videos of it? >> No. I wanted to check that out. Is it old footage or is it? >> Yeah, it’s a footage from the early 1900s and it is in a zoo. The one cool thing about the thylacine is that it had some unusual anatomy and then it could open its mouth super wide. So there’s some video showing it open its mouth and it looks like something from a sci-fi movie. So it’s pretty fascinating. You’re like, “What, what the what?” [LAUGHTER] So it would have been really cool to actually see that or see more video of it. It’s just like some little pieces. But go on to YouTube and search thylacine, and there’s some old video, black and white from before it went extinct. >> Cool. Yeah, I’ll have to check that out for sure. I asked if it was recent because I know there’s still people that claim they’ve seen it, and every now and then grainy videos and such pop up on YouTube, but [OVERLAPPING]. [LAUGHTER] >> That’s the [OVERLAPPING]. >> This is or has already brought us to some of the themes in these papers. [LAUGHTER] But I think we could start off by talking about the Haddad et al article on habitat fragmentation, which I know Rama you’re going to take the lead on helping us, walking us through it and maybe any questions and things, and Kendra and I can jump in as we go through. But what did you think of this article? >> Yes. So I do quickly want to review the difference between habitat loss, habitat fragmentation, and habitat degradation. I think most of our students are pretty familiar with those concepts. But sometimes when we talk about habitat loss, we’re lumping fragmentation in there and not thinking about, so habitat loss is just like in a forest ecosystem where you lose a third of the global forests. That’s obviously going to reduce the overall area for biodiversity, but then the remaining habitat is fragmented. So you have these three main drivers within fragmentation which are lots of smaller areas, so a lot of the remaining forests are less than 10 hectors. Then isolation where species have a difficult time moving between these patches and then the impacts of edge, because we know edges are very different ecosystems where there’s different species there, there’s different amounts of light, different temperature and moisture levels. I thought that was useful just to start with that, and then the third being habitat degradation. So even when we have these remaining habitats, they have different disturbance regimes, they’re impacted by invasive species, lots of top predators, and changes to the community composition. So you might think the Southeast US is very forested, but it’s a lot of loblolly pine that’s managed for forestry and very low diversity. So I thought that was useful to start out with. Did you guys want to jump in on that? >> Yes, I think there’s a figure in one of the I don’t think it’s this article actually. Its a >> It’s my [OVERLAPPING] app. >> Yes it’s a just a bit >> Broke. >> Broke [OVERLAPPING] which has like. >> Broke, it’s all right, broke. >> Yes, it has that nice like, it’s like a circle and it’s like, “Oh, the green circle” or some thing’s like “This is contiguous habitat.” Then it has a cut and a half and it’s like, “This is habitat loss.” It’s been dropped down 50 percent, but the remaining 50 percent is all together. Then it shows a final figure which is where it’s been reduced 50 percent, but it’s totally fragmented little pieces, like a jigsaw puzzle that’s missing half the pieces. So I think your point there that it’s not just the loss of total amount of habitat, it’s when it’s all cut up and especially with roads, we see that occurring in many areas. So? >> Yes, I think that’s a great figure for visualizing this concept. So I was excited to talk about this paper because I think it’s really important for our students to read this paper for two reasons. One is just a great concise review of these large-scale long-term studies of impacts of habitat fragmentation on species persistence and species richness, and all these other factors associated with biodiversity loss. I remember this article didn’t exist when I was in graduate school. I remember trying to read 50 papers on this topic and synthesized them in my own mind for my comprehensive exams. [LAUGHTER] I think what you end up doing is focusing on the nuances and differences between these studies and see if you loose the forest river trees and thinking there really is a consensus here. So I think that’s why this paper is so important. Not only did they summarize the findings of these different studies, but they did a meta-analysis, which means that they took the data from all these different studies and reanalysed it, so they could show a consensus amongst all of these different studies of different ecosystems, in different timescales, and size scales so. [NOISE] >> Yes. >> That’s written this review paper, had you thought of it back then? [LAUGHTER]. >> I never wanted to pump in an idea, I would have been published in graduate school. [LAUGHTER] >> You needed 20 co-authors like they have though? >> Yes, that’s the problem that really well thought out. Well done review papers requires 20 individuals in the tops of their field would have been studying this for a decade. But I do think it’s something that our students can think about when they’re doing their synthesis papers and review papers. Not just to summarize what all of these researchers have done, but to think of the literature as something you can ask a new question of and maybe you don’t get to the point where you’re doing a total analysis of the data for many articles, but you can look at a different scale or just ask a new question that the original researchers were asking. >> Yes, this one I think it also highlights these great long-term research studies that have been going on for decades and they’re manipulative or experimental studies not just looking at existing forest fragments, but they actually like went in and manipulated these areas using lots of venture funding money, National Science Foundation and other groups. But that, that by doing that, by taking that experimental approach, they are able to control for all these other variables and for most scientists, come up with results that are a little considered more rigorous because you’ve actually just manipulated, cut all the trees and created these fragments of varying sizes that are replicated and then you’ve analyzed them for many years. I know, the seventh author on this paper, Thomas Lovejoy is actually going to be coming to Cincinnati Zoo and speakers [OVERLAPPING] narrows lecture [BACKGROUND]. So we’re going to we’re going to be streaming that and recording it for dragonfly students as well. So that’s very cool. There’s some other huge names in this field on this paper in terms of the authors. I know that Thomas Lovejoy, his particular project was conducted in Amazon and was the minimum critical size of ecosystems project, in the Brazilian Amazon. I looked this up and I found out that since it started in 1979, it’s resulted in 562 publications. >> Yes. >> Thing and a 143 dissertations and theses. >> Yeah, when I was a graduate school, I was really interested in biological dynamics and forest fragment study. Then, Hedad actually came and spoke at UGA. I think he’s a graduate of UTA. There are two talks that I went to in graduate school and I think that one by Hedad. Which is one of the two that, I mean, there are only two talks that I went to, sorry [OVERLAPPING]. They are the most influential. [LAUGHTER]. One of them was the Hedad, because I just left that talk thinking like, this is what science can be. If you have long-term funding and the opportunity and that you can actually answer these questions in ecology because so often we end up kind of nibbling around the edges of questions and we do observational studies where we can, have controls of replicates or baseline data and then we can’t control those confounding variables you are talking about. Then we just look at correlations and argue about how to interpret them. Or we can do really small-scale studies like looking at the community inside of a pitcher plant, which is really cool. But how does that scale help to the massive ecosystems that we live in as far as their complexity and size. So yes, I think as a graduate student knows, is like, you have funding, you can actually answer these questions. [LAUGHTER] >> Let’s see. So I mentioned they did a good job reviewing the history of these massive, large-scale, long-term studies. You already mentioned the early ones by [inaudible] and all that group, where they are looking at persistence and immigration between patches and really the consequences of fragmentation, and then the Savannah River Site stuff, which was a lot of [inaudible] in that group. We know this is a huge problem. Can we create corridors and improve connectivity? Is the size and shape of the corridor matter? So there is that whole phase of these studies and then more recently, they were looking at synergys with climate change and land use and invasive species. They mentioned the Mellotron study in France, which I’m not very familiar with. But apparently, they’re able to control temperature, and moisture, and all these other factors while also looking at fragmentation, which is pretty amazing. >> I always loved the name in the Mellotron [OVERLAPPING]it just sounds so, of course, it makes me think of transformers and things like that. I would imagine more of these are going to try and get into and it would be really expensive. But to find ways to manipulate CO2 and temperature and moisture regimes and things, perhaps using different enclosures and things. >> Right. >> I mean, one of the things I found most alarming about this paper was just their statistic about, what was it, 20 percent of, sorry, 70 percent of remaining forests is within one kilometer of the forest edge. >> Yeah. >> I think it was maybe 20 percent or so was within a 100 meters. Essentially, just getting at fragmentation through time and where it’s going to be happening the most little bit. >> That’s something I thought a lot about when I’m looking at giant panda habitat was that, if you look at a certain scale, there’s a certain amount of habitat. But then if you zoom in and look at the different patches, they’re so tiny. It’s really disturbing how each of those patches couldn’t really support one panda. >> I would think pandas would need an enormous home range. >> It’s not as big as you would think. Their home range is only, I don’t remember exactly. But it’s not as big as you would think. But this patches are actually smaller than that. I think because they’re not predators, the habitat, the home range isn’t as big as you would think compared to a black bear, or grizzly bear, or something. >> Yeah, herbivores are going to need smaller patches than omnivores or predators. So that makes sense. Did you see the good patch of bamboo. >> Yes, exactly. >> What I liked about this study that was fun, we’re talking about scales is just the variety of scales of these, from the moss fragmentation study, which was just really small all the way up to the Brazilian study, which was big. So that was really interesting to me. One thing that this paper made me do, is want to learn more about all the different projects. >> Yeah, definitely. >> What is this wag wag? I haven’t heard of the wag wag. >> I haven’t heard of wag wag either. >> So what is wag wag and who are the people behind it to? Because we know that who’s behind some of the Brazilian work. Whose behind a lot of the Kansas work? Do you guys know the scientists? >> I don’t. >> No. I’m not familiar with that one. >> When I first saw it, I thought it was maybe some of the work by Tillman, but he’s not in Kansas. But it looks just like his study. I was interested to find out sort of who started them, what they’re about, where they are. But I guess I might have to read 500 papers [LAUGHTER] or thesis but it would be really cool and maybe I haven’t looked in the literature. But to look at, is there like a review paper of here’s what we know from the biological dynamics Brazilian study on fragmentation, summarizing all of the stuff we know? There’s probably some technical reports out there but I’m wondering if there’s some reviews because that’s what I really wanted to know. >> I think they did a good one with biological dynamics one after 20 years in the late 90s, early 2000, there is a pretty good review paper. But then you’re right, there’s all these other studies but I don’t think have had necessarily review papers among them. >> Mellotron. >> The mellatron. >> The moss one just because I love moss and I love little patches of things [LAUGHTER] looking at my backyard, we’ve got these patches of moss and my wife was, we’re laying down wood chips in some areas and she’s like, do not cover this moss, [LAUGHTER] I was like, oh, I’m right there with you. I’m not touching that moss. I love it. But how different species react to different scales and there is a spider biologists I knew, who was basically like, a lot of spiders, they basically will have one meter radius little hunting territory. If they’re a wolf spider, some of the smaller species of wolf spiders that live in tropical areas, when you shine your headlight and you see all their glowing eyes looking back at you. When I first did that, I was just blown away. I had no idea there were that many spiders. This was in beliefs and he was like, they were all distributed. Each of them had their one meter. It was not random at all and you could just see how the ecosystem, for them, was operating on this totally different spatial scale. So anyway, that’s just an aside. But I mean, what a way to spend your life and your life’s work on these long term projects and learning about the effects of fragmentation and habitat loss. I think it’s pretty amazing. Rama, do you have anything else or Kendra on this article before we switch gears? >> I guess just to summarize. I mentioned that there’s a lot of noise in all this data but when they are able to look at a consensus to this meta-analysis, they show that habitat fragmentation reduces species persistence, species richness, nutrient retention, tropic dynamics and movement of species across the board. Consensus is very clear once you get rid of some of this noise and take the time because there are all these lag effects. So at first they would show a butterfly species actually increase for five years after you fragment something. But if you look at the long term, those patterns really solidify into loss of species. >> Lag times totally freak me out because [LAUGHTER] whenever I start feeling optimistic and I’m like, we still have black rhinos. Still got them, I mean there’s like 5500 left and their populations has actually been increasing slightly over the last few years. Then I’m like but in 500 years, what’s the likelihood they’re still here? When you’re down that low and your habitat’s been altered that much, it just seems like that longer term outlook is pretty bleak. >> I think that gets to your point about the passenger pigeon. How could you imagine it would ever go extinct? It’s something that can fly away. How could you kill every last single one of them? But they’re gone. >> Yeah. Actually, I’m guessing with passenger pigeons, it was a little bit of the alley effect, which maybe we’ll talk about with Kendra’s article because I think they talk about it a little bit. Let’s switch to that one, which is the burke et al., 2008 article on the synergies among extinction drivers under global change. Kendra, what do you have to say about this one? >> That was the perfect segue too. Speaking of bleak [LAUGHTER]. >> So this is a good review paper looking at extinction, what’s causing extinction. They’re saying okay, we know all this stuff is causing extinction. If we look at table 1 in here, we know all these things about what’s causing mass extinction, what humans are doing, all of these different things. These are what we know. We know the four big players. I never heard this term before. >> [inaudible] [OVERLAPPING] >> I wrote it down here. The evil quartet. >> Evil quartet. I haven’t heard that either. >> That Diamond came up with. The main four things that are causing extinction and some of the details about them. So that quartet is overexploitation, habitat destruction, and of course, the fragmentation that we just talked about sort of falls under there. Invasive species and chains of extinctions. That also relates to those trophic cascades, and what we talked about with the chestnut. That other things probably went extinct when the chestnut went extinct because of their reliance. So we know all these things about extinctions, but what we don’t know is how they interact. So what happens when you have all of them occurring or some of them occurring, and reality is that’s usually the case, what happens when they interact? So the fact is it’s not just additive. So you don’t have 10 percent extinction caused by this and 10 percent reduction by this. When you put them both together, it’s 50 percent reduction. It can act synergistically. I always tell my students it’s 2 plus 2 is 6. >> [inaudible]. >> Because we do tend to look at these things, we have all these multiple threats coming, but we focus on them one at a time instead of looking at them altogether more holistically, realizing they can interact synergistically, non-additively, and then to throw some more complexity and more of a bleak outlook, let’s overlay climate change on top of it all. Let’s look and see how that interacts with all of these. Because a lot of people haven’t looked at that as much as they looked at the other causes of extinction in the past. So I thought it was a good review, a little bit sort of bleak and a little bit overwhelming to think about all the different things but I thought they did a good job explaining what they were trying to explain. >> I guess it should be an evil quintet now with the climate change. >> Right. >> I guess you can quibble and be like why aren’t pathogens or disease? But I guess that can fit under introduced species usually but there’s other ways this can all be grouped. But yeah, the general idea that if you’ve got multiple stressors, you could have a few things. I mean, they say it could be additive and it could also be non-additive. It could be that climate change just makes it so the generalists, the wide ranging species, are persisting, and maybe those are the ones that would be persisting anyway due to habitat loss. >> [inaudible]. >> Partially additive, I guess they call it. >> I think they call it partially additive, so that’s like if climate change has the same effect as habitat destruction, they are both reducing the range in the same way than they’re not additive, it’s just going to reduce it a certain amount. >> Right. I’ve thought about like positive feedbacks which are not good. They’re not [LAUGHTER] positive I would say. >> They’re not cool. >> They’re not good at all, but positive in the sense that they create more of the issue or the problem. So if you have a species that is susceptible to climate change and so it’s maybe restricting it’s range and then the habitat within its range is fragmented. So it’s getting even more which I think that point is made here. Then with climate change, just looking at climate change alone, like people talk about the increase in temperatures can have a positive feedback loop on things like if you have melting of snow cover in the Arctic than more dark material showing like soil or rock substrate, which absorbs more heat, which causes more melt, and then you have release of methane. So all of those things are creating a cycle where there’s more and more impact on climate change. So all these things they can go the other way of a negative feedback loop like with climate change. One of the things that has been floated is the idea that with increased warming, perhaps there’ll be increased cloud cover and therefore less sunlight radiation in certain areas and actually cause a cooling effect. So it could potentially mitigate some elements of warming. So I guess I’m just [LAUGHTER] diverting a little bit off on a tangent there. But just the general idea that when you have multiple bad things happening, they can counteract each other or they can affect in different ways. [NOISE] What else? I mean that there is this MVP concept here that they have in the figure which is the minimum viable population size. They talk a bit about that. I don’t know if Kendra Yeti notes some of that. >> Not too much. I mean that’s the magic number that everyone tries to find. >> [LAUGHTER]. >> Of course beyond that you start to get into stochastic effects and extinction vortexes. That sounds pretty scary, where you sort of spiral down and extinction is accelerated once you hit that minimum viable population size. There’s a lot of issues with trying to find that magic number but they put it here as danger. Don’t cross that line. Once your population gets small enough, you get all kinds of things like the Allee effect and more susceptibility to stochastic events [NOISE] and genetic drift. All of those kinds of things happen with small population. So when you get to that point, it’s sort of the death knell for the species. So you’re trying to keep everything below that threshold. >> So we’ve talked about the Allee effect. I mean how do you guys think about that and as to what exactly it is. I feel like it’s in some ways it’s very simple and in some ways it’s kind of complex. [LAUGHTER] >> Yeah. So I mean, briefly, the Allee effect is you have to have a certain number of individuals. It again another threshold thing. If you have a certain number of individuals for some important thing to occur usually successful reproduction, survival, fitness level. If you get below that it might look like you’ve a lot of individuals, you’re like, “Shoot, there’s a lot of birds out there. There’s still 400.” But it turns out the birds need 500 out there to feel sexy and mate. If they see less than 500, they’ll just walk around and never get on Tinder and find each other. >> [LAUGHTER]. >> There’s this threshold. Leks are a good example in birds, where you have to have a certain number in a lek before everybody gets all excited and wants to mate with people. >> [LAUGHTER]. >> With each other. Do [OVERLAPPING] you guys know of any other examples? Those are kind of the ones that I teach in my class for Allee effect is sort of mating rituals. >> I don’t think of any offhand. Do you know Rama? Anything come to mind? >> It just makes me think of fishes that find each other through pheromones or something. It’s just, they’re so far apart. They never detect those pheromones in the environment to track each other down. >> I guess, like lonely George, one of the Galapagos tortoise subspecies that would be an extreme example of just getting down to that point where you actually do not have anyone else to mate with. So there is no way you can continue your fitness for the next generation is zero in that case. So I guess, if you think about like, if there’s two million individuals of a species and they drop down to one million, you may have a 50 percent reduction in the average, the number of individuals in the next generation. But then, when you get below that threshold you were talking about, Kendra, the decrease in the next generation output base precipitously drop off because of that critical need, where they just can’t find each other for mating or they don’t feel sexy enough, as you said, or whatever pheromones. I wonder, with the passenger pigeon, I imagine something like that must have happened. I feel like it would have been hard for him to drop off in that way without it. >> I don’t know it as well as I should, exactly. I just know it’s mostly over-harvesting that led to their decline, but I did read some stuff that they were very social. So probably there was a real effect because you usually see that more in some social systems communication. >> [OVERLAPPING] for this. >> Yeah. There was a couple interesting little things in here, little nuggets that I got that I didn’t know. The one being this dung beetle example, which is pretty interesting, where over-hunting of mammals led to less dung beetles. Dung beetles are super important ecosystem service providers, where they recycle nutrients and then also probably stop the spread of parasites by getting this dung away. So you’re not exposed to any worms in there, or anything. So I thought that example was pretty interesting where when you lose those, you lose the dung beetle and trees are affected. So that was a new one for me I hadn’t thought about. >> You made that point really well, and Rama’s example of the American chestnut, and how we think of it as the American chestnut becoming functionally extinct or largely disappearing from these forests. We think of it as one species, but really every extinction we can think of, I’m sure also for the thylacine and for the passenger pigeon, there was probably dozens of unknown extinctions that went along with that that we just haven’t fully understood whether it’s the parasites associated with those species or mutual lists in some way. >> For the passenger pigeon, they mentioned that perhaps a louse went extinct, [LAUGHTER] that specialized on the passenger pigeon. But good news, that lice did not go extinct, they found it in the [NOISE] [inaudible] or something on another species of pigeons. >> Interesting. >> You see is parasite and yet all these smaller organisms that you don’t even think about that went extinct with the bigger one because we tend to think of these charismatic species going extinct, but all the little critters, even the lowly louse might have gone extinct. So it’s pretty interesting to think about. >> They give that other example of the sharks, that large predatory sharks in top-down control their eating size, the elasmobranchs, which are the rays, skates and small sharks. Then I guess, when they’re gone, the rays, skates and small sharks increased to the levels that they eat up all the scallops. There’s tons of these examples, but I really like them. They’re just interesting when you think about the ecology, even though they’re sad. [NOISE] They also get a little bit into these large international agreements and things, right? Is it this one or actually maybe it’s the next one? >> Maybe I fell asleep during that part. I think it’s yours. >> Okay. Well, maybe we’ll jump into that. I feel like I saw some note here about them talking about one of the United Nations. Just the fact that it’s important to study all these different factors. Let’s switch gears into this other article, the Brashares et al, 2014. Wildlife decline and social conflict. So far, we’ve just been talking about like what causes extinction or endangerment and how it works together. Now this one really gets into how that affects humans. I think it takes a different approach and focus than we tend to think of. I tend to think of, species goes extinct and how it affects. It’s sad, we can’t see that species anymore. So there’s a loss of the intrinsic value of that species to the world. But this one really gets into focusing on the poorest people of the world who when they’re living in these areas of wildlife depletion, it necessitates them, sometimes leading into increasing exploitation of those species or creates another positive feedback that is negative. [LAUGHTER] They really talk about some very interesting examples from pirates in Somalia who justify their raiding of ships to protect the sovereignty over their offshore fishing grounds because other international ships come in to fish because they can’t get the fish quotas they need, so they come into Somalian waters, and then those people who were doing more local fishing also need income and so they end up in this pirating situation. They link it to the drug trade, and slavery, and crime syndicates. So it’s just a lot here of tying social welfare to wildlife loss that I thought was very unique to read about. What did you guys think of this article? >> I’m not a wildlife like human dimensions person, so I definitely got a lot out of it. It made me think of a lot of the studies looking at the relationship between climate change and conflict in the Middle East and Sub-Saharan Africa who can support themselves. Then climate change impacts their ability to do that and then they get recruited by these extremists. It’s very bad. >> Go ahead, Kendra. >> I thought this was pretty interesting. I’d never thought about the connections. I thought about like black market trade and who’s making the money from that, all the criminals, and you think about all the crime movies you’ve seen. I’d thought about that, but I’d never thought about, with fisheries collapsing, you’ve got to hire effort and so you get child slaves. I never would have thought of the connection between dwindling wildlife and increases in child slavery. But it makes sense. It’s just, you don’t often make those connections. >> They have that interesting figure there, which is like fish stock decreases. So the fishermen have to increase their catch [NOISE] unit, the catch per unit effort somehow, so they can actually find cheap labor demand will increase, just like you just said. This whole cycle that leads to food insecurity and poverty increases and all these things and violence increases. In fact, there’s this quote by a Senegalese fishermen in this article that says, “In 10 years time, people will go fishing with guns. We will fight for fish at sea. If we cannot eat, what do you expect us to do?” Which I think is a great voice to have included in this article. I know people and a lot of Dragonfly students and instructors feel very against poaching and very against hunting of endangered species, but [LAUGHTER] when you’re starving and you don’t have much choices, it’s way more complex than simply being a bad thing. I just read this article about rhinos and talking about black rhinos earlier discussing 5,500 now. Namibia, as a country, has considered allowing just five of their growing population of rhinos to be hunted a year for $400,000 each. So that would generate two million dollars US and would fit within what they see as their projected growth rate. It could be maintained with that level of harvest. It would have these huge profits that could really benefit conservation in the area. So controversial issue [LAUGHTER], but I just wanted to mention that. >> I think there’s so much potential for putting a management of resources back into the hands of the people who are closest to it. But then I also think there’s so much room for that to go wrong. >> It really needs to be [NOISE] a concerted, collective effort maintained over the long term. Because you can put management back into the hands of the people closest to that resource, and if they are feeling desperate then they’re going to go move back towards overharvesting. >> Yeah, I thought that was a great point of this article, that they were really arguing for putting the control back in the people’s hands. I think that, I was just looking for this term and it’s something like eco-colonialism, but [LAUGHTER] I don’t think that’s quite what I’m thinking of. But it’s this term that basically gets at the idea of all these international agreements including the International Union for the Conservation of Nature, some of their guidelines and rules and different treaties which conservationists tend to think of as a very good thing. But they have also essentially exerted control over other countries resources. When it comes down to it, I think this article starts to make that point that that may not be the best strategy. They give the example also of Namibia, of these community conservatories that exist in Namibia where the people living there want the ability to harvest within reason, some of these species that currently they are not allowed to harvest or sell products from. So again, it’s an issue to think about, but yeah, I think there’s a lot there to consider. Kendra, did you have anything else on this article? >> No, not really. >> I think we’ve covered them all, [LAUGHTER] a lot of different issues. So I think we’ll wrap it up. Any final overarching thoughts you guys want to jump in and share, takeaways you would consider? >> Maybe this is too much of a discussion, but how do these three papers fit together? [LAUGHTER] I think the first two do, but I’m wondering why the third? It has to do with declining species, and I liked it. It was interesting, but it was coming out of left field. What do you think, why was this chosen? >> Yeah, I felt that too. It reads so differently. The other two fit within, they feel very academic. They’re research articles, and in this one, it’s published in a journal that is not typically on my radar as somewhere to read. It’s like a magazine article. It has this picture of this child. But I think it’s an important connection to not just think about it in a more academic sense that the other two articles, it feels problematic, certainly, what they’re talking about. But this one for me just made it hit home in a different way, how this all effects the world, and humans in particular. >> The title of this discussion, I think it was extinction and its consequences. The first two articles are more like extinction and its causes. [LAUGHTER] So I guess you could think of consequences as the extinction for taxes and how extinctions cause more and more extinctions. But from a human perspective, this last one [NOISE] actually talks about consequences for humans. >> Yeah, I liked it. It just felt different even though I thought, why did they pick that? >> Yeah, you wouldn’t typically hear a discussion of crime syndicates and these groups in Africa, like Janjaweed, Lord’s Resistance Army, and Boko Haram. Those headlines are almost always focused exclusively on human issues. I think this is one of those crosscutting articles that hits a couple of different disciplines and areas of thought. But it’s a great question because it’s something that sometimes is missing, I feel like from the pure ecological literature in my opinion. >> Yeah, I think students will have some good conversations around this too. So I think it was a good choice. >> Yeah. >> Thank you both for joining and talking about this, and thanks for those of you listening in. We hope this is useful to you to complement the written asynchronous discussions. We hope you’re enjoying these conversations and we’ll look forward to doing this again soon. Take care. >> Bye-bye.
Conclusion and Feedback
It’s Kevin Matteson again. I hope you enjoyed that discussion. As promised, I did want to share some of the feedback we’ve been getting on these podcasts just so you know how your fellow students are reacting. I just have two comments to read, and these are quite positive. [LAUGHTER] But again, we’re open to all sorts of feedback. So feel free to let us know where you’re listening, what you found interesting, any unique things about invasive species or extinction or whatever it may be that you’re thinking about. You can send those to me again at matteskc, M-A-T-T-E-S-K-C@MiamiOH.edu, or at my phone number, 513-529-0837.
The first comment is from Natalie and she just said, “Hello, I just want to provide some positive feedback about the IBD podcast. I found the first discussion very helpful to my comprehension of the articles, and I look forward to hearing more throughout the semester.” So thanks, Natalie, that’s awesome. This is all about universal design, which is a term in education and pedagogy that basically involves reaching out to people in various formats, because we all learn in different ways. So it’s nice to hear that this is aiding in your comprehension of the articles.
Then we’ve got another email from Kerry who said, “I just want to drop you a line, that you know that I am loving the podcasts. I’ve never really listened to any before. Too many choices, not enough time, so this was new to me. First and foremost, I really appreciate being able to hear the instructors interpretations and discussion of the articles. Sometimes I’ll gloss over something I think may not be important or miss something completely, but it’s brought up and discussed in detail, giving me a more thorough understanding. Second, it’s really convenient. I found that I can’t do anything else while listening because I don’t want to miss any part of the conversation. But to be able to listen on my phone, computer, or in the car is wonderful. Last, it’s really great to hear everyone’s voices to match up with their photos. It shouldn’t matter, but somehow it does. Hearing the instructors tones and inflections really gives the listener a better sense of intention and provides a greater impact to the meaning of their words. I’ll leave it at that, but let everyone know that their work is appreciated and that they have a fan in me.” So thank you so much Kerry. That is wonderful to hear.
We really appreciate the positive feedback. We keep exploring different things. Dragonfly is really unique in that we have so many wonderful students all over the country and the world, and we want to find unique ways through technology to reach out in a personal and convenient manner. So thanks again, and we’ll look forward to hearing from others down the line if you have the time to let us know. Have a great day everyone. Bye.