In 2017, the museum opened the second Expedition Alaska show, one of an ongoing series of exhibits that highlights contemporary museum collections research. This show took a look at the work of the Mammals Collection and specifically, museum research into Hoary Marmots. Here, Link Olson, University of Alaska Fairbanks professor and Curator of the UAMN Mammals Collection talks about the research that led to that exhibit, ongoing research into marmot habitat, melanism, and predation, and how collecting practices have expanded and advanced over recent decades.
The More You Look is a production of the UA Museum of the North, on the campus of the University of Alaska Fairbanks and the ancestral lands of the Dena people of the lower Tanana River. UAMN illuminates the natural history and cultural heritage of Alaska and the North through collections, research, education, and partnerships, and by creating a singular museum experience that honors diverse knowledge and respect for the land and its peoples.
In 2017, the museum opened the second Expedition Alaska show, one of an ongoing series of exhibits that highlights contemporary museum collections research. This show took a look at the work of the Mammals Collection and specifically, museum research into Hoary Marmots. Here, Link Olson, University of Alaska Fairbanks professor and Curator of the UAMN Mammals Collection talks about the research that led to that exhibit, ongoing research into marmot habitat, melanism, and predation, and how collecting practices have expanded and advanced over recent decades.
The More You Look is a production of the UA Museum of the North, on the campus of the University of Alaska Fairbanks and the ancestral lands of the Dena people of the lower Tanana River. UAMN illuminates the natural history and cultural heritage of Alaska and the North through collections, research, education, and partnerships, and by creating a singular museum experience that honors diverse knowledge and respect for the land and its peoples.
One of the reasons we've been interested in alpine small mammals is that alpine ecosystems are very similar to island ecosystems in that they are isolated habitat patches separated by non alpine seas of boreal forest or shrub vegetation. And that creates opportunities for evolutionary diversification between different islands or alpine areas. And that can be at multiple different spatial scales. So we can look at different mountain ranges, all the way down to different peaks in the same mountain range. Each one of those provides a window into the evolutionary processes that generate biodiversity. So, people like me who are trained in evolutionary biology, who are interested in these natural systems that provide lots of different replicates that we can access in the field, even though Alaska is relatively inaccessible. We have just so much alpine habitat here that with sufficient support ( in the terms of funding for fieldwork), we can actually build these impressive sample sizes in terms of both specimens, but also the localities from which those specimens are collected.
Roger Topp:Hello, and welcome to The More You Look, your behind the scenes journey into museum collections, research, exhibition, and public programming from Fairbanks, Alaska. I'm Roger Topp, Director of Exhibits Design and Digital Media at the UA Museum of the North and host for today's episode. In 2017, the museum opened the second Expedition Alaska show, one of an ongoing series of exhibits that highlights contemporary museum collections research. This one took a look at the work of the Mammals collection, and specifically museum research into Alaska's marmots. The exhibit closed last year to make room for a new exhibition on the work of the Museum Herbarium. But before it left, I sat with Link Olson, University of Alaska Fairbanks professor and Curator of the UAMN Mammals Collection. In this episode of The More You Look, Dr. Olson talks about the research that led to the exhibit and the research that has continued after.
Link Olson:As with most of the research that happens in a museum, our research is based on specimens and their associated data that we go out and collect from the field. And the data that we're able to associate with the specimens in what's approaching the mid-21st century are vastly richer than the data we could collect even 30 or 40 years ago, because we know what to do with the material. So, what we're collecting in the field now takes far longer to prepare, because to go back to the origin of mammal preparations, when people first started collecting mammal specimens in the field, they would bring back the entire animal or just dissect out the skull and the pelt and turn them into study skins. And so the standard mammal museum prep for most small mammals consisted of a skull and a skin. And fast forward nowadays, we refer to the extended specimen as not just those original parts in the case of mammals, but everything imaginable that can be saved from which we can learn something about that animal, either its ecology, or its evolutionary history, and everything in between. So our current sampling protocol in the field for Hoary Marmots is to collect as much data from their environment in terms of basic spatial data. Where were we? The coordinates, the time, the weather that day, photographs, and possibly even samples of the vegetation nearby. When we have the specimens in hand that we collect in a number of different ways. We're usually immediately collecting information that is time sensitive. We bring them back to the lab, sometimes we freeze them whole and then over the winter, when we've got more time and more staff to work with these. we start doing dissections and saving representative tissue types. We've started saving eyeballs from small mammals because the lens in a mammal's eye is the only tissue that continues to grow at a constant rate over the lifetime of the animal. So by dissecting out the eye lens and weighing it, we can get a good approximation for the animal's age. because otherwise there's there are very few ways to reliably age a mammal. Eye lens weight tends to be the most accurate. You can also section teeth. So that gives us a window into the demographics, some of the population parameters. Sex is relatively easy to determine, age is not. So by combining a couple of different methodologies, we end up with demographic parameters that allow us to actually ask some ecological questions and even behavioral questions, which people don't think of when they think of dead specimens, but we get windows into the behavior of organisms through physical attributes on their bodies. So we've been visiting alpine regions throughout the state, and more recently have concentrated in Southeast Alaska because of its topographic and geological complexity, and also its complex history with respect to the retreat of the glaciers. One thing we know is that most of the range occupied by Hoary Marmots today was under ice several times during the ice ages of the Pleistocene, and with the retreat of the last glacial expanse between 18 and 20,000 years ago, and today, there's been a northward increase and expansion of the Hoary Marmot range to where we now have them in Interior Alaska and up into extreme Northwestern Canada. That should leave a predictable genetic signature that we can then follow through and test and see if it conforms to our predictions. And just about every time we look into those patterns--that's called phylogeography, the history of genetic variation within a species. So between populations--and every time, it seems that we do genetic research expecting to find a simple answer, the answer ends up being far more complex. And that's what really gets us excited is why do we see patterns that we didn't anticipate, and with the Hoary Marmots, we've detected this pattern of two different expansions northward following the retreat of the glaciers. One of those seem to start in what is currently Montana, and it came up this interior Rocky Mountain corridor. The other expansion originated somewhere in or around western Washington State and followed the coastal corridor. And it seems like those two expansions were independent, and were not exchanging genes until they met again, somewhere in Interior Alaska. And where they meet is where people who are interested in the questions were interested in, will try to see if they are able to reproduce again. And we've confirmed by being able to sample one locality where we know those two, previously isolated genetic lineages came back into contact, that they do freely interbreed, and so speciation hasn't yet occurred. The other thing we're trying to track by developing the kind of baseline data that we collect when we're out in the field is the extent to which Hoary Marmot habitats are being pushed upslope, which we would predict based on historic climate change that was happening far more slowly than it is today. And of course, more rapid climate change that we've observed over the past century and a half. And we're sort of at the before stage now. And it will take people doing what we're doing 10, 50, 100, 200 years from now to develop the after picture, to see what happens to Hoary Marmots isolated in these mountain ranges or on these individual peaks after multiple decades of continued climate change, and we anticipate that they will become more isolated from one another, that some populations will likely become locally extinct. And as those isolated islands become smaller and smaller and separated from one another by greater and greater distances as the ocean of boreal forest and shrub habitat rises. That may not bode well for Hoary Marmots, and we expect that to happen faster in the more southern parts of their range, and are in fact seeing that with respect to the alpine habitat in the lower parts of montane North America, the more southern parts. We have known--we collectively, scientists have known==that there is a population of Hoary Marmots in southeast Alaska in and around Glacier Bay in which some individuals appear to be jet black. And certainly there are lots of mammals that are black--maybe not lots, there are some mammal species that we're all familiar with that are black, either throughout the entire species. or will often have black individuals such as both jaguars and leopards, we occasionally see black individuals. But for a diurnal mammal that's not terribly advantageous, because you can see a black animal from much farther away than you can see a mottled gray and brown animal against a mottled gray and brown background. So it doesn't make much sense that we would see the persistence of this black color type. And we went down to see if there were still melanistic--that's the technical term for dark, uniformly dark, colored animals--to see if there were melanistic marmots still in southeast Alaska, because no one had looked for them and over a century, and to see if we could figure out what's causing this melanism and why it might be persisting. And the answer to the first question is definitely, there are still lots of melanistic Hoary Marmots that seem to be isolated in that part of southeast Alaska, Glacier Bay and the neighboring Chilkat Mountains. And we don't see them anywhere else. And thanks to the work done by one of my PhD students, Kendall Mills, we know which gene in which variant of that gene causes some marmots, who have one or two copies of this to be entirely black. Whether or not it serves any adaptive function remains to be seen. The fact that we don't see melanistic marmots outside of that area suggests that there might be something preventing its spread, but that may not have anything to do with the gene itself, they might just be geographically isolated. Our own observations of melanistic versus the normal or what we would call wild-type individuals side by side in the same colony don't suggest any behavioral differences between them. In fact, we were surprised to see some melanistic marmots as conspicuous as their wild-type brethren, because you would think they wouldn't want to draw attention to themselves. So we immediately start to think of predators. We know from our own experience that we can see these from as far away as a mile or more, they really stand out. And if we can see them from that far away, then any predator relying on vision to find prey is going to see them from that far away. But the predominant predator of Hoary Marmots throughout most of their range is Golden Eagles. And golden eagles do migrate through Southeast Alaska on their way to more northern localities, but they don't stick around. So if you spend much time in southeast Alaska, you'll notice a lot of Bald Eagles, which tend to prey mostly on dead fish, but no golden eagles. And it might be that this very visually conspicuous morphotype is able to persist down there because no one's going after Hoary Marmots. We have never seen a predator go after a Hoary Marmot in Southeast Alaska. And it may just be an accident of geography that melanism has been allowed to persist down there. There are ways of experimentally testing that which...which would be fairly straightforward. We could create models and stick them out in golden eagle country and see if golden eagles go after black marmot models more than they do gray marmot models now it'd be a fun project for someone to do. Check check check. Theres a Hoary Marmot on a rock about 30 meters from us and we're about to fly an eagle kite to see if we can elicit a response. Marmot is definitely aware of us but these are a pretty habituated group of marmots so it hasn't alarmed. My PhD student who has been working on this has uncovered a really rich literature on the advantages and disadvantages of having dark colored hairs. And a case can be made for and against having dark colored hair. And that's probably happening in nature. So there are probably tradeoffs. Marmots, even the wild type marmots are pretty conspicuous. If they're out moving, they're big enough that you're going to see them, which means they're vulnerable to predation. And if you're a marmot like most other animals, you live to reproduce. And in order to reproduce successfully, you got to stay alive and be healthy and attract mates and--most importantly for marmots--survive hibernation. So there's a trade off in being outside and eating but vulnerable to predation versus being in a burrow, relatively safe from predation, but not eating. When you're out in the sun and you're warm-blooded mammal, you're expending less energy to stay warm the more solar radiation you're soaking up. And the darker colored you are the more solar radiation you're soaking up, and it's warming you. And so you're saving that energy that you're then able to redirect (not consciously, of course), to reproduction. So it might be that there are some evolutionarily selective pressures to retain this gene, or this variant of the gene that causes melanism in the population. But at the same time, there are pressures against that variant taking over the entire population because they're more subject to predation. We also think that darker-colored hairs are less susceptible to microbial degradation. In fact, that's been shown in birds with black feathers that black feathers don't suffer the same microbial digestion as nonblack feathers, and no one's showed that for mammal fur yet--we're trying to. There is also research suggesting that higher concentrations of melanin, which is the protein that causes pigment--including hair and skin--to look dark, are correlated with immunosuppression. So there might actually be immunological advantages to having dark-colored [fur]. As with any biological phenomenon, there are just umpteen different ways you can think about it and study it and ultimately conclude that nature is very complicated. Since we're continuing to collect specimens and methods for making use of biological samples continue to evolve, we're thinking more and more about what can be done with the parts of a specimen that historically would have been discarded. That includes stomach contents and even feces. So right now we are preserving all of the stomach contents and all of the feces to be sent to a commercial lab that will use a DNA meta barcoding approach to genetically identify all of the food items in a marmot's stomach. And you can do the same thing with their feces. And the expectation or the hope at least would be that those analyses would give you the same answer that if you looked at their feces versus their stomach contents, either way, you're going to get a pretty good idea of what they have eaten,. But we don't know that yetm so that might be an interesting thing to do since we have a pretty big sample size of these all from the same area. With a couple of important variables. Some are collected at sea level. We call these beach marmots. It's not where people think of marmots being but in Alaska and Northwestern British coastal British Columbia, Hoary Marmots, this classic alpine species seem to do very well at sea level. And that begs many questions. Are they down there because there's a longer growing season? Because there might be different food resources? Are they staying there year round? We've answered some of these questions. We know now that there are colonies at sea level that stay at sea level and reproduce and stay down there. Are they ever exchanging genes by recolonizing the alpine or vice versa? And we think we know the answer to that. Are they perhaps deriving salt, which is usually a very limiting or limited mineral? To a lot of animals. Most people who hunt are aware that there are naturally occurring salt licks where large-bodied mammals will congregate because they can't get enough salt from their diet, or at least not as much as they would like. Ranchers put salt licks out for cattle to try and attract them to areas that the cattle wouldn't normally go. So it might be that Hoary Marmots are using intertidal habitats to feed on kelp and seaweed and also derive some more salt. So, these are all things that we can get at through both direct observations but also through specimen based investigation. Since we developed this exhibit, we have continued to collect more specimens and to pay more attention to what we can do with some of the parts that have traditionally been overlooked. One of those is saving the eye lenses is so that we can get a proxy for age. And what would be nice is if we had a series of known age specimens to calibrate that against, but we don't. The best we can do is confidently identify marmots that have overwintered once. So if a marmot--marmots are born in June and July in Alaska, they go down and hibernate for six to eight months and then come back out again in their second summer--that's about the oldest that we can confidently age a marmot. Beyond that, they all start to look the same. So we don't have any known age specimens that are older than either pups that were born that season, or yearlings that were born in the season before. So we can plot a very simple line of eye lens weight against age in pups, or yearlings, but that's not going to tell us much about marmots that are much older. And we do know from long term tagging studies done by other colleagues that Hoary Marmots in the wild can live in excess of 11 or 12 years. Do they live longer than that? We don't know. Another common method of aging mammals that also requires known age individuals to calibrate is the more traditional cementum analysis where you section one of the molars or pre molars, and literally count the rings, but one ring doesn't necessarily equate to one year. So here's asecond proxy, and we compare eye lens weight to cementum analysis. There's a third technique that a former undergraduate actually helped us develop, where you look at the degree of fusion of the bones in the skull. So when mammals are developing in the womb, and well into their early years, the bones in their skulls haven't completely grown together and fused. And in human babies, you can feel this on the top of the skull--our bones are still not completely grown together when we're born. And depending on the species of mammal, that can take days to weeks to months, or possibly even longer. Once they fuse, or once they start fusing, they fuse directionally. So depending on the two bones that are coming together, they might fuse from back to front or front to back. And if you can measure the extent to which that fusion has occurred, say 20% of that suture is fused 40%, what have you, then that's another proxy for age and I had a student look at 17, different sutures, places where different bones and the skulls come together. And she developed a metric like that she would say whether it was 20, or 40, or 60, or 80, or 100% fused, and combine all those for 17 different measures, and come up with a third proxy for how old these are. And that's a study yet to be done. On all the specimens from which we have collected eye lenses and teeth is to see how tightly those three correlate. And if all three of them or even two of them correlate tightly enough, two of those the teeth and the cranial sutures can be assessed on historic specimens, which would mean instead of being limited to the relatively small number of specimens that we've collected just in the past five or six years, we would be able to apply this to the more than 1,000 specimens that have been collected over the last 120 years. Which means that we could look at changes in demographic parameters. There are predictions based on climate change and its effects on things like growing season that can be made about relative age. We might think that marmots are living longer now, because they're surviving the first few years where young marmots are most susceptible to dying during hibernation, and they die during hibernation because they're unable to accumulate the fat reserves necessary to survive hibernation. With climate change, the growing season for most plants has increased, which means the active season for marmots which need live plant material has also increased, which should mean--I think--that they're more able to survive hibernation, which then would suggest that the average age of a marmot today should be greater than it was 50 or 100 years ago. Now, there are lots of other potentially confounding variables that could throw all of that off, but it's at least possible, in theory, to go back and add all these historic samples. But that work has yet to be done.
Roger Topp:Thank you to UA Museum ofthe North curator Link Olson for the insights into the Mammal Collection's ongoing work throughout Alaska. The museum could not conduct this work without public and private sector partnerships, and without state and national funding through agencies such as the Park Service and the National Science Foundation. Explore the museum's website for more information about recent and forthcoming projects, and perhaps even ways to get involved. Before we go, a reminder that the museum maintains a free mobile app for iOS and Android devices. Take an audio tour of any of our galleries from the comfort of where you are now. Look for the UA Museum of the North Mobile App. The More You Look is a production of the UA Museum of the North on the campus of the University of Alaska Fairbanks and the ancestral lands of the Dene people of the Lower Tanana River. UAMN illuminates the natural history and cultural heritage of Alaska and the North through collections, research, education, and partnerships, and by creating a singular museum experience that honors diverse knowledge and respect for the land and its peoples. Thank you for listening. Please subscribe, share, and rate the program. This helps other listeners discover more about not only the work of this museum, but quite possibly other museums in their neighborhoods. The more you look, the more you find.