Virtual Science Café: Mapping Mammals, Avian Wingmen, and Life Through Mass Extinctions
Aired May 13, 2021
Naimah Muhammad:
Hello everyone. Hello and welcome to today's Virtual Science Café program, presented by Smithsonian's National Museum of Natural History. My name is Naimah Muhammad, and I am one of the public program coordinators at NMNH.
Meaghan Cuddy:
And I'm Meaghan Cuddy, an ocean education specialist at Natural History, and together we will be your hosts for this event. Whether this is your first time joining us or you've attended before, we are so glad to have you here. And although we can't see you, we do want to feel your energy. So please let us know in that Q&A box where you're tuning in from, and you can send your questions throughout the program in that same box located at the top or bottom of your screen so we can get to your questions during our Q&A.
Naimah Muhammad:
Yes. Awesome. So of course, we want to acknowledge the folks who made this program possible. This series was developed with science communication resources generously provided by Smithsonian Regent and former museum board member John Fahey and his wife Heidi Fahey, with support from the Selig-Krichbaum Endowment.
Meaghan Cuddy:
And our sincere thanks go out to them for making this possible as well as everyone else who supports our museum's mission and outreach.
Naimah Muhammad:
Yes, thank you so much. Very, very much. And we also want to thank our D.C. restaurant collaborator, Busboys and Poets, who were the restaurant collaborator for this winter spring season. So we want to thank them and we hope you were able to take advantage of the discount code if you are local and place an order or got to enjoy some of the specialty themed drinks for the season. So again, thank you to Busboys. And audience, if you had a chance to order or you're sipping on one of those drinks, please let us know in the Q&A box as well.
Meaghan Cuddy:
Oh man, that sounds delicious. So before we turn it over to our guests for tonight, there's just a couple of housekeeping notes to go over. So we have three awesome speakers who will be presenting back-to-back lightning style talks, and then we'll be answering your questions in the second half of the program. So that Q&A time does go by really quickly, so in order to help us get to as many questions as we can, you can submit your questions as you have them during or right after each talk. And again, you can post those questions in the Q&A box, which is located in the bottom center of your Zoom screen.
Naimah Muhammad:
Awesome. All right, so let's go ahead and get started. Our first speaker is Ingrid Rochon. Ingrid, do you want to come here and join me? Hello. So excited to have you as part of the series and to kick things off. So Ingrid Rochon is a museum technician in the Department of Mammals at the National Museum of Natural History, where she keeps track of the who, what, when, and where for every one of its 600,000 specimens stored behind the scenes. By pulling together field notes, historic maps and handwritten tags, specimen locality data helps scientists understand the distribution of life on Earth and how ecosystems have changed over time. She has over a decade of experience working in vertebrate collections, and tonight she'll tell us more about her project mapping mammals and how by understanding the extent of our collections at NMNH, scientists can pinpoint the places we have yet to explore. So please join me in welcoming Ingrid and I will let you take it away.
Ingrid Rochon:
All right. Let me start sharing the screen. Let's go here. Let's get that up. There we go. All right, so greetings everybody and welcome to the museum tonight. My name is Ingrid Rochon and I'm a museum technician and data manager in the Division of Mammals. Unlike the other speakers you may have seen in this series and my colleagues that will follow me, I'm not exactly a research scientist. My job is, as Naimah said, to care for the 600,000 specimens in my department that our staff scientists to use. And the closest analogy to my job is that of a reference librarian for the world's largest dead zoo. And if you've ever used the services of a reference librarian, you know that we're a fount of knowledge and that we always have exactly that one rare or obscure little tidbit of information you're looking for.
And a little like our research scientists, it's my job too to synthesize sense out of a messy world. When you visit the museum, what you see on display is our clean modern exhibit. You see our lions and tigers and bears, and you learn their names and some cool facts about them and how they fit into this narrative about evolution and the history of life on Earth. But what you don't see is what I'm working with behind the scenes, and that's thousands upon thousands of specimens crammed into drawers and vials and jars. And for the elephant skulls, of course, we have open shelving. It's a little hard to fit an elephant into a jar. And each one of these specimens is dangling one or more handwritten tags. And each of those tags is cross referenced to 100-year-old notebooks, archives full of illustrations, the loose leaf musings of curators, long deceased, punch cards and printouts from the dawn of computerized information systems and even vintage vinyl of mammal vocalizations.
What I've found that the exhibit doesn't really tell you is that every specimen was collected by a particular person at a particular time, at a particular place on planet Earth. And it's all of that associated data just as much as the object itself that makes our collection so valuable. So let me show you what I mean and show you just a little bit of what I might do on a typical day at work. Let's say for the sake of example, I have a researcher interested in Southeast Asian squirrels. At the bare minimum, I can take you to our squirrel room. Yes, we have a room for squirrels. I can open the Borneo drawer and I can pull out the skin of a cream colored giant squirrel, which is catalog number 151762. I'm a bit of a details person.
But I can do one better than that. The tag tells me that it was collected by a man named William Lewis Abbott on the 2nd of January 1908, and I can go to our archive room and pull out his handwritten notebook to tell you that it was collected at a place called Sigam on the island of Sebuku off the southern coast of Borneo. But when I Google a 100-year-old anglicized place name, I get zero hits. So I can do better than that. I go to our map room, in the age of COVID, I go to our digitized version of it and I pull out our 100-year-old maps and I become an expert for the day in Dutch and Malay and God-awful English cursive script written a century ago, and with a bunch of background knowledge and a little bit of luck, I can tell you that that squirrel came from here. I mean specifically here, red arrow marks the spot.
And if that's not good enough for you, I can cross reference the map to satellite imagery. I can throw an arrow radius on my estimate and I can give you a literal set of latitude and longitude coordinates to tell you that that squirrel came from here. And did I mention that I can play this exact same game of treasure hunt with any of our 600,000 specimens? It's a lot of work, so why do I do it and what use is it? What can we learn from mapping our mammals? And why is it important for me to keep all of these physical things after I'm done distilling them down to a data point? Well, museum collections tell us where mammals are.
Have you ever opened up a field guide and seen a range map like this? And have you ever wondered how they're made? If there are any bird watchers or birders, I know your lingo, in the audience, you know that we draw these maps of where we expect birds to be based on your observation. But mammals are not quite like birds. They're not flashy, they're not loud, they're typically not willing to visit your backyard when the sun is up and shining. Mammals like this deermouse are small, sneaky, and typically only observable when we catch them in the hand to put them in a museum collection.
So drawing up a range map necessitates a species identification from that physical specimen, our field notes describing its preferred habitat to draw our initial boundaries on the map of where this species might be and a final refinement of that map based on where we actually found them. So when you see the term expert drawn range maps, those expert drawn maps for mammals would not exist without the work I do.
We can use mammal collections to tell us where species have lived in the past. So you remember that squirrel collected by William Lewis Abbott in 1908? Well, here's the man himself and here are some of the mammals he observed on the trip he took that year up the Kendawangan River in Borneo. He writes about civets, muntjacs, and gibbons he sees in this, quote, "Uninhabited district covered with secondary jungle and long grass," and he remarks upon new settlements that are springing up along the Bornean coast. At the time Abbott visited the island of Borneo, it's estimated population was only two million people, and today it is 16 million people and almost 10% of the island has been deforested and converted to oil palm plantations. When I identified the exact spot on Earth that these specimens in our collection originated from, I could literally see the grid lines of the plantation roads and the unnaturally regular patterns of tree cover that tell me that the rainforest here has been fragmented and destroyed.
A century of collecting that's built up our library of specimens from 1908 to the present day can show us how mammals have responded to human-induced environmental change over time. So if I traveled to the Kendawangan River today, would I still see the same mammals? Our 21st-century range maps tell me that I would still see those civets and muntjacs at the Kendawangan site, which is indicated here by the red arrow. But I would no longer find gibbons. And we know from field notes of researchers that the gibbons need diverse forests with a tall canopy layer in which to live. They can no longer survive in the sort of environment that I find along the Kendawangan River today. And without that history stored in museum collections, we might not know that they ever lived there at all.
And finally, because every library needs a good mystery section, using our collection and its associated data to map Earth's mammals lets us know what we don't know. So the entomologists may have me beat when it comes to the smallest organisms. And Stewart may tell you later tonight that it's harder to find a clam the size of a fingernail somewhere on the ocean floor. But there are mammal species so rare that we only have a few hundred of them in museum collections worldwide. There are species like this pied bat pictured on the lower right that are so rare that we've seen fewer than 10 of them ever. And when I see a range map like this, one of the smokey white-toothed shrew, so few of them have ever been photographed that I had to substitute a picture of its closest relative to give you any idea of what it looked like.
When I see those scattered little patches of orange over such a huge swath of land, I know that there are missing pieces of information that our scientists have yet to find to fill in those gaps. What habitats have been lost to throw up barriers between those different populations? Maybe have there been human assisted introductions of this species to places where it didn't previously live? Or the most likely explanation when we have so few data points to work with, what places on Earth have our museum scientists not yet fully explored?
So this is a map I put together of not just every mammal, but every specimen in the entire museum with an associated set of geocoordinates. And you'll see all of the dots on North America, where we're located. This is for our museum, and museums worldwide have maps that would show you different coverage, but all of them together are still incomplete. I am continuously adding to this map as I draw connections between our existing specimens and data, and I help our researchers add to it every time we work together to find answers to their scientific questions, whether that's in the rainforest and Borneo or South America or right here in West Virginia where you might find me with a deermouse in hand.
Each gray area on that map is a place that Smithsonian scientists have yet to explore in our quest to discover new species and better understand the story of life on planet Earth. So with 200 years of institutional history and one of the world's largest ever-growing resources of scientific information at my fingertips, I know that we will be busy for centuries to come. Thank you so much for tuning in tonight, and I will turn it over to Stewart, who'll tell you about wonderful clams.
Meaghan Cuddy:
Thank you so much, Ingrid. That was so cool. But I'm not going to lie, the idea of a squirrel room will be haunting my dreams for the rest of the week. But that was such a wonderful talk. Thank you so much. Next we're going to be turning it over to Stewart Edie. Stewart is a new paleobiology curator at the National Museum of National History. And in his work, he likes to think about why the flora and fauna of places like Maryland and Virginia looks so different from that of places like California or for that matter, Hawaii, New Caledonia or Kamchatka. He also asks questions like why were mass extinctions so devastating to past life? And how did biodiversity then recover? He mostly goes about answering these questions using marine bivalves, which you may know as clams and mussels and more. And tonight he'll be showing us how these unassuming, but important organisms are actually spectacularly diverse and provide some insights into how biodiversity response to things like climate change and mass extinction. So with that, I'll turn it over to you, Stewart.
Stewart Edie:
Thank you, Meaghan. All right, so first thing, I have a lot of unstable Internet with me right now, so I'm actually going to pop off the video to preserve as much bandwidth as possible, so I apologize for that. But we'll get started right now.
All right, so thanks everyone for tuning in and thanks so much to Ingrid because this talk is built on that extremely detailed and valuable collection study. So now I'd like to share two stories, one about how biodiversity changes across the globe today and then through time. And you'll see a surprise, something that my team and I didn't expect to find, something that we still don't fully understand. But before we get there, we've got to dig into a little bit about what I mean by the term biodiversity.
If you're like me, you may imagine teams of scientists trudging through a forest or swimming over a coral reef, counting the numbers of species of birds and beetles and trees and ferns. Or if you're in the ocean it could be corals and fish and crustaceans and molluscs. Biodiversity is truly remarkable. But it turns out the biodiversity is so much more than just the numbers of species. In fact, it has many components. Chief among them is that aforementioned genealogical unit that we can all just picture it in our heads, and that is the species.
But species quite often have unique forms or shapes. They could be circular, oblong, spiky or smooth. Nature can take on some rather inventive geometries. And by this point, you've likely noticed that I'm showing images of just a certain type of animal. As Meaghan mentioned, these are the shells of bivalves. And if you've been out to the beach, you've probably seen thousands of these exoskeletons washed up on shore. And if you've ever picked any of them up and noticed how they're different, then you're picking up on that third component of biodiversity, that's their mode of life. Or we also call that their ecological function. And it turns out that bivalves have a remarkable diversity of life modes or ways of making a living if you prefer, because for example, oysters somehow manage to cement themselves to the sea floor while being underwater, and scallops can swim and mussels have these super strong silken threads that they can attach themselves to rocks so they don't get washed away by waves.
And what's really incredible, at least to me, is that bivalves can even be predatory. So this is the bivalve equivalent to the T. rex. It swallows up these unsuspecting copepods that wander along the sea floor. It's not bad for an animal that doesn't really have a head, but before you forgo ever going into the ocean never again because there are carnivorous bivalves, take note that this little guy is about the size of the tip of your pinky finger, and it typically lives in very deep parts of the ocean, so it's still safe to go swimming.
But back to the point because when we study all of these components of biodiversity at once, we get a much clearer picture of how biodiversity grows and it declines and it perseveres on the planet today. But as you're going to see, it can also lead to new questions about how biodiversity may respond to catastrophic changes in Earth's climate and environments both now and in the geologic past.
So first I'm going to start by asking how do these components vary in space? And by space I don't really mean across the solar system, I mean geographically from place to place on this planet. So as species decline from one place to another, does the diversity of ecologies and forms also decline? Or can some of the components decouple and show different types of change or no change at all?
So to find out, let's zoom in first to the eastern coast of the U.S. that we're probably familiar with and focus on two key areas, the subtropical Florida Keys and the high temperate Gulf of Maine. This is just north of Cape Cod. And thanks again to the museum collections from around the world and are managed in these extremely valuable and detailed ways that Ingrid has shared with us, we're able to identify some 355 species in the Florida Keys. That's pretty impressive and probably a larger variety of seashells than most of us are used to finding on the beaches around D.C. But if you'd like to really be blown away, I'd advise taking a trip out to the West Pacific where we can find upwards of 1,000 species.
Anyways, I digress a little because in the Gulf of Maine it's much less impressive only around 90 or so species. And this matches patterns that we see in other major animal groups too, including birds, plants, insects, really you can name it and they'll have this latitudinal diversity gradient. But what about ecology? The ways that these animals are making a living. Species diversity drops by 75%, but does ecology do the same? In the Keys we find 37 distinct modes of life. But now if you focus on the diorama, because in the Gulf of Maine that drops to 28, it's not nearly as steep as the species richness gradient. But in the end, both species diversity and the number of modes of life change with latitude, so surely shape is doing the same thing. At least that's what I expect.
And in the Keys we have these large spiked shells, but plenty of small smooth shells. In the Gulf of Maine, we're only finding relatively small plain shells. And this is what we would call a decrease in variance of shape with latitude. It's not really directional like we saw with the species diversity in the ecology. It's more a winnowing of forms as we go to higher latitudes. But in total, what we've got are three decreases in these components across space, which is okay because that's more or less what we expected.
Declines in all three of these components tell us that climate is a very important regulator of biodiversity today. In the Keys, there's relatively little difference between summer and winter conditions, and this corresponds with a remarkable stability and resources that bivalves need to live, that is their food, and that stability begets diversity. But in the Gulf of Maine, there's a much larger difference between summer and winter, and this makes resources more variable, and thus the region supports slower biodiversity. And there are many wonderful little things that go on along this longitudinal diversity gradient such as this delicate dance between predators and prey. But it's this difference in climate that's arguably the most important factor.
But of course, being a paleontologist, my team and I knew that there were other major drops in species diversity throughout Earth's history that is drops through time. So we asked, do those drops in species diversity also show drops in the diversity of ecologies? As a side note, we're still working on shape. It's hard enough to measure that variable in the modern ocean, let alone in the ocean 200 million years ago. But nevertheless, our fossil finding ways led us to two key moments in Earth's history.
The first was at the end of the Permian, some 251 million years ago, and we almost lost multicellular life together at this mass extinction. And I'll let that sink in for a second. This was some 80 to 90% of species extinction. The second interval that we looked at was the end-Cretaceous. This is where a rock fell out of the sky and took out the dinosaurs, that is the asteroid. And we lost some 70% of species at this extinction. Now, you've probably noticed that both of these are comparable in magnitude to the types of species loss we saw across the gradient and latitude today. So we had to go back in time and look at the ecologies at these two different mass extinctions events. And we found 17 modes of life in the end-Permian before the mass extinction and 30 before the in end-Cretaceous. And based on what we saw in the spatial gradient, we absolutely expected catastrophic losses in functional diversity too. But that's of course, not what we saw. In fact, virtually every mode of life survived both of these mass extinctions despite that enormous loss in diversity.
And just to remind you, I'm not talking about these modes of life re-evolving after the extinction. I'm talking about genetic continuity from before to after. So some poor oysters cemented to a rock halfway around the world from the north shore of Mexico where the asteroid hit survived, and they carried with them that remarkable ability to lay down cement underwater. And the same goes for swimming scallops and for those mussels that make those silken threads. We're still figuring out exactly how and why this happened. But we think it has something to do with whether these ecologies were spread across the globe or if they were restricted to very specific places on the planet because being widespread tends to help with survival in times of crisis.
So to recap, we were utterly shocked to see the persistence of ecological diversity across mass extinctions. We were certain it was going to follow the same pattern that we saw with latitude today. And we're itching to find out exactly what's going on with form. And spoiler, it seems to be persistence, just like what we see with ecology. But even as we continue to work on that, we're left with a pretty tough question to try and answer right now, one that deserves a little bit of urgency. And that's what will the nature of future biodiversity loss look like? Will if decouple and resemble the persistence of modes of life like across those past mass extinctions? Or will it resemble the couple declines in biodiversity dimensions that we saw with latitude in today's oceans?
The pressures that species are experiencing right now are similar to what they've encountered in the geologic past, but those pressures are coming at them much faster and more intensely than ever before. And so it's unclear whether entire ecological groups are going to survive this pace of change or not, but this is something we absolutely need to figure out sooner rather than later. Thank you all for listening. And with that I'd like to turn it over to Peri for a wonderful talk on cooperation.
Naimah Muhammad:
Thank you, Stewart. Thank you so much. I love the surprising nature of the findings of your work, but also thinking of these bivalves of these little T. rex spirits in the deep ocean. But glad that they won't be there when I'm swimming around. But okay, let's keep it moving. And just one more reminder to the audience, keep the questions rolling. Go ahead and use the Q&A box so we can try to sort through and get through as many as possible.
So I want to bring on our third and final speaker, Peri Bolton, and Peri you can go ahead join me here. Hello. Peri Bolton is a visiting fellow in the Vertebrate Zoology department at the National Museum of Natural History. Her current work is in collaboration with Chris Balakrishnan's lab at East Carolina University, and the Manakin Research Coordination Network, where her broad interest and use of genetic methods addresses questions in evolution and behavioral ecology and conservation. In her own words, she has a penchant for colorful critters, so it's no surprise that she's exploring the gene expression in the brains of the colorful manakin birds. And she'll tell us more about that tonight. So Peri, take it away.
Peri Bolton:
Hello everyone. Thanks Naimah, and thanks Stewart and Ingrid. Today I'm going to follow on from these two talks and tell you about how tissues that are often housed alongside museum specimens can tell us about the physiology and genetics of an organism and how this can then tell us about how the animal lives its life. So I'm going to take you on a journey of our groundbreaking research using tissue samples to uncover what physiology and genetics makes an avian wingman.
At some time or another, I'm sure we've all felt it can be difficult making an impression in the dating world. And it turns out birds feel the same way, and many species have evolved making displays to try and make an impression on the opposite sex. For example, birds of paradise have so many weird and wonderful blue plumage ornaments and dances to try and attract female attention. And the birds I study are manakins, and these jungle birds have evolved bright colors and acrobatic feats that are unrivaled in the bird world. But they do this all in the hopes that the girls will swipe right.
All of these males in all of these birds do these displays alone and compete with one another to attract female attention. But sometimes dancing alone is just insufficient to catch her eye. The wire-tailed manakin of the Western Amazon dances cooperatively. A territory-holding male will dance alongside a subordinate non-territory holding male called a floater. This cooperative relationship is mutually beneficial to the males as territory holding males that do cooperative dances farther more offspring, and floaters who dance cooperatively are more likely to gain a territory later in life.
So like some humans, these manakins actually recruit wingmen to help them attract female attention. And this sort of cooperative behavior is extremely rare among birds. No more than 20 species in over 10,000 species of birds exhibit any kind of cooperation or coordination among males in their mating displays. So on the right here, I'm showing you the manakin tree of life, the birds that I study, and circled are two species of manakin that dance cooperatively. And it is absolutely remarkable that this rare behavior has actually evolved multiple times in this family of birds, given that it's so rare amongst all birds universally. So many scientists are fascinated about why this cooperated behavior has evolved at all. And other scientists are interested in how they cooperate, and I'm one of those scientists.
So what do I mean when I say I'm interested in looking at how these birds cooperate? Well, when a female turns up at a territory, what happens inside the manakin that helps him to decide to display and whether to display with a wingman? In particular, this means looking at the amounts of different hormones in the animals and hormones also influence what genes are turned on and off, which can connect the hormone to other functions such as seeing the female and the decision to dance. And a lot of this happens in the brain, and we also know that particular regions of the brain have different roles to play such as vision or executing the dance.
So I'm interested in how genes in the brain are influenced by hormones and in turn how that influences behavior. And it turns out that little work has been done on this type of behavior. And so we needed to figure out where to start our research. One hormone of particular interest was testosterone. This hormone is famous for its role in influencing male sexual behaviors and male aggression, but this hormone is far more complex and subtle than it is often given credit for. For example, in the golden-collared manakin, we know that sensitivity to testosterone is part of how these males produce athletic feats in their mating display. So our team thought that if testosterone is important in manakin dancing and in male competition, it might be involved in this in the wire-tailed manakin cooperative dance.
So our team, led by a Brandt Ryder from the Smithsonian Migratory Bird Center went into the jungle and studied the hormones of the wire-tailed manakin and found that testosterone influences the cooperative tendencies of wire-tailed manakins in an unusual way. Team found that in territory-holding males, as the amount of testosterone in the body increases, territory-holding males become less cooperative or less willing to dance with other males. In contrast, with floater males, those without territories, they tend to do more cooperative dances as the amount of testosterone increases in the body. So this relationship is really unusual and we don't really know why this relationship exists, and so part of my research is trying to get at the genes and brain regions underlying unusual relationship.
So to dig deeper into our questions of how they cooperate, we measure gene expression in 10 different brain regions as well as the pituitary and testes. And we picked these tissues because we know that they respond to testosterone. So not only are we asking questions about a really unusual behavior, but no one has ever explored the mechanisms of this behavior in such detail in a wild animal.
So I said we're measuring gene expression. What is that? So genes are tied up in our DNA, and a molecule called messenger RNA is used to copy that information stored in the DNA. Then the information that from that gene that's encoded in the RNA is then translated into enzymes in the structural proteins that make up our bodies. So then gene expression describes the quantity of messenger RNA in a cell or a tissue. And by measuring that, we can get an idea of what enzymes and proteins are doing in that particular tissue.
So you might also recognize the word messenger RNA or RNA as a key component in the Moderna and Pfizer a COVID vaccine. You may also remember the discussion about how these vaccines need to be stored at extremely cold temperatures in order to preserve the RNA. Our team faced the same challenge in the wire-tailed manakin. Achieving the cold temperatures necessary to preserve RNA and then measuring expression is very difficult when the bird you study lives in the Amazon rainforest.
So how did our field team overcome the challenges of the rainforest and collect tissues to preserve the RNA? Well, they had to work really quickly and tirelessly in the hot jungle to catch these birds and sample their tissues, and the quickness was so that the tissues didn't degrade. And then the tissues were then stored immediately in cooler boxes full of dry ice, which keeps the tissues at a temperature of minus 109 degrees Fahrenheit, which is sufficient to preserve the RNA. They were then stored in special dry shipper containers, which maintains these temperatures for up to 21 days. Now, all of this was done without electricity, which is important when your birds again live in the rainforest. And then this allowed the time for the samples to be shipped to the U.S., where I would then measure the gene expression.
So once the tissue samples were back in the lab, our team dissected each of the brain regions and then took the mRNA from them and measured the sequence of nucleotides, that being the building blocks of DNA and RNA, and then using high performance computers, we can compare the mRNA sequences to genes and count how many messenger RNA molecules there are associated with a given gene. So in this example, this individual has higher expression of gene and this individual.
So across all 10 brain regions, we measured most of the active genes, which represents over 16,000 genes. That's a lot of information about what's going on in the brain brains of these birds. So now we can use this information to start to build a picture of how gene expression varies across the brain and other tissues in the wire-tailed manakin. So one way we're building that picture is looking at gene expression in males with high testosterone relative to males with low testosterone, remembering that testosterone influences how cooperative a male is. And we find that gene expression levels across our thousands of genes differ depending on whether you're looking at genes in the testes or in different parts of the brain.
So all of these patterns are really complicated, so for brevity, I'm just going to focus on one particular brain region for today, a small part of the hypothalamus. This particular region is showing us some really interesting genes like androgen receptor that have high expression in males with high testosterone. Androgen receptor is really important because it binds to testosterone and then acts on other genes to turn them on and off. So what this result means is that as testosterone increases, so does the body's ability to respond to that signal. And then the action of this gene on other genes may then at least partially explain the overall gene expression patterns we see in the hypothalamus. So androgen receptor is influencing multiple genes in that brain region or more broadly across the bird.
So after all that, what makes an avian wingman or how do wire-tailed manakin males cooperate? Well, it's complicated, but using tissues from a behavioral study on wild birds, we show that this cooperative behavior is influenced by testosterone, which is echoed in patterns of gene expression across thousands of genes in the brains of these birds. But we are only just starting to scratch the surface on reading what's going on in the minds of these birds. But the hard work of our team has enabled for the first time a glimpse into the complexity of bird brains, and we are just starting to unravel the puzzle of this unusual behavior. Thank you everyone for listening.
Naimah Muhammad:
Thank you, Peri. Thank you Peri, Stewart, Ingrid. I'm going to go ahead and invite everyone back on and the co-host Meaghan, and we will dive into some questions. Awesome. So before we get started with audience questions, we all had a chance to get together before the program and hear a version of the talks, and I happen to know that there are some looming questions, so maybe before we open it up to the audience, Stewart, do you want to get us started with the question that you had for Peri?
Stewart Edie:
Yeah, absolutely, if I can. So Peri, that was fantastic. Super fun. So you mentioned that there's this particular kind of cooperation that's rare in birds, but how about other types of cooperation? Penguin pairs come to mind. Would you say that birds in general, are a cooperative type of animal?
Peri Bolton:
Yeah. So Stewart's asking, in case the audio dropped out, it did a little bit for me, about the prevalence of cooperation across birds. So birds are quite famous for males and females cooperating to raise young together, and that's a form of cooperative behavior and that is done to mutually ensure their genes go into the next generation. So what's really unusual about this behavior is that these males are unrelated, so by dancing with another male, you're not ensuring your genes get into the next generation.
Stewart Edie:
Thanks. That's really cool because I immediately thought that this was going to be another altruism situation or kin selection like with prairie dogs or ants, close relatives helping to propagate the population. Yeah, that's really cool. Thank you for sharing.
Naimah Muhammad:
And I just want to share a comment here that says, "Yeah, avian wingman talk." So we love it. Meaghan, do you want to take over the next question?
Meaghan Cuddy:
Yeah. All three of these talks were so wonderful, So thank you all so much. I have a question for Ingrid. So Ingrid, both Peri and Stewart talked a little bit about some of the more surprising findings in their research, and so I'm wondering if you've ever had any surprises in your mapping activities, in your mapping work?
Ingrid Rochon:
The most wonderful part of my job is that every day is different because when you have 600,000 specimens, there's no way I could lay eyes on all of them in a lifetime if I went and opened up a drawer every 10 seconds. So I'm constantly finding, I'll open a drawer and say I'm looking at deermice today, and I'll find something that was collected by Teddy Roosevelt and be like, "I'm delighted to add this data point to my set today." So just the history that pops out every time I work in the collection is continually surprising and wonderful to me.
Naimah Muhammad:
That's amazing. Stewart, a question for you. So at the end of the talk you cracked a door open on the next steps in your work, specifically alluding to the fact that form is following a similar pattern and persisting across extinction events. So could you expand a bit on this and the next steps in your work?
Stewart Edie:
Right. So we only have preliminary evidence for this because we're micro CT scanning a lot of fossils from these extinction events. So we can actually replicate what we did from say the Florida Keys to the Gulf of Maine, but this time from before the extinction to after. And getting CT scans of fossils is way more difficult than modern shells, partly because they're in rocks for the most part and it takes some computer trickery to extract them, but we can do it, it just takes more time. But what we do know so far is that we do see a persistence in the variety of forms across the extinction events based on what we've been able to measure so far. So it's entirely different from the latitudinal gradient.
Meaghan Cuddy:
That is so incredible. It's a life finds a way type of moment, for sure.
Stewart Edie:
That's right.
Meaghan Cuddy:
Peri, I have a question from Rosalyn who would like to know what do these manakins eat? What are they chowing down on?
Peri Bolton:
So manakins mostly eat fruits, different fruits that live in the jungle, which is unusual. Their closest relatives are mostly insectivorous, and so we have a whole bunch of questions revolving around what's so special about frugivory? Has that enabled them to become so colorful and dance like they do? So they eat fruit.
Naimah Muhammad:
Okay, and pivoting over to Peri to you. Oh no, sorry, here's a question for Ingrid from Advait. And the question is it seems unlikely that animals are uniformly distributed within their ranges as depicted by range maps. So do we have a better way of depicting where species are actually found?
Ingrid Rochon:
Leave it to Advait to ask me the hard questions.
Naimah Muhammad:
Besides, he's from NMNH.
Ingrid Rochon:
Yeah. Of course, mammals are not uniformly distributed in that patch of orange on the map. I simplified things a bit because range maps like the ones you saw are effectively a hypothesis. Mammals move in space, distributions change seasonally, environments change over time. Point data is point data. That is what it is. But everything else is us generating a hypothesis to lay over this map.
And if you want to see really good range mapping, I recommend you check out eBird, which is a project out of Cornell University, I believe. And they provide just incredibly granular range maps that are drawing on thousands upon thousands of observations, so just loads of point data. They're drawing in environmental information from satellite imagery and there's a lot of statistical modeling that goes on to generate a probability heat map that you can lay over a landscape to give you a better and more accurate idea of where you will find organisms on Earth rather than just these blobs of orange. But we all know these blobs of orange because we see them in the field guide.
Naimah Muhammad:
Ingrid, if you send me over the link, we can send that out to the audience.
Ingrid Rochon:
Sure. Yeah.
Naimah Muhammad:
For the detail-oriented people.
Meaghan Cuddy:
Our next question is for Stewart. Stewart, Diane is wondering what caused the Permian mass extinction event that you spoke about?
Stewart Edie:
Yeah. That's a great question because the end-Cretaceous is so easy in a sense, that the asteroid hit. But the end-Permian is thought to have been this perfect storm of stressors from increased temperatures, to CO2 concentrations, ocean acidification, ocean anoxia. It was a truly horrible time. And while this is still an area of active research, it's thought in part to have happened because of very large volcanic eruptions, which are what we now know as the Siberian Traps.
Naimah Muhammad:
Okay. So next up we have a question here. This one is for Peri, to you, and that is have the floaters ever tried to overpower the territorial males? Oh, you're still muted. There we go.
Peri Bolton:
That is a good question. I wouldn't be surprised, but I don't know. I haven't been in the field observing the birds myself, so I can't answer that question with any authority I'm afraid.
Naimah Muhammad:
Well, let us know what you find out if there's an uprising and they take over in your research as you've learned more.
Meaghan Cuddy:
All right, Ingrid, we've got a question for you. Pretty specific one. What kind of mammal was on the first slide of your presentation?
Ingrid Rochon:
Tree shrews. They are not shrews, nor do all of them live in trees. But they're kind of closely related to primates. But the closest visual comparison I guess would be a squirrel. Tree shrews. I love them.
Meaghan Cuddy:
Poorly named.
Naimah Muhammad:
All right, let's keep it rolling. There's a lot of questions. Thank you all. We're trying to get through as many as possible. Okay, so our next question here is Stewart, for you, do you know if there has been any work done looking at changes in the different ecological strategies in response to pulse perturbations like the Deepwater Horizon oil spill?
Stewart Edie:
Yes, actually there have been.
Naimah Muhammad:
And maybe you can explain the Deepwater Horizon oil spill as part of that question too.
Stewart Edie:
Right. So the Deepwater Horizon oil spill was a massive release of crude petroleum from a drilling rig in the Gulf of Mexico. I forgot how many years ago now, maybe within the last decade or so. And there were definitely very acute short-term mortality that came about because of this event. But we're also now seeing a return, although very much incomplete still to a pre-spill state. We've yet to know if and when we'll get all the way back. There's still oil down there from what I've learned, and it's becoming more dispersed. But we know from other catastrophes like this that we don't necessarily return to the previous state in terms of the way the animals are making a living. So we're going to need to continue to do very careful monitoring over the next couple of years to see exactly how we're progressing.
Meaghan Cuddy:
That is really interesting. Peri, next question is for you. Someone would like to know, do the testosterone levels in the birds correlate with their ages? So for example, are lower testosterone birds usually older than higher testosterone birds?
Peri Bolton:
That's a good question. And based on what we know, that is roughly true, that there is a correlation between testosterone and age. So the territorial birds tend to be older and they tend to have higher testosterone than the younger birds, which are the floater birds. So yes, there is this age effect there on testosterone.
Naimah Muhammad:
Awesome. So I think we have time for a few more as we are nearing the close. A question here, let's see. Stewart, another one for you here from Rosalyn who's wondering about the size dependency of mass extinctions, even with the taxon of relatively small organisms like bivalves, are the larger species more likely to go extinct?
Stewart Edie:
Right. This is a great question. I wish I had more time to talk about it because we actually did look at this in bivalves, so I can talk about it in that context. And what we found was that there was no size activity with bivalves. We would've absolutely expected that the really small low energy animals would've been the ones that snuck across. They didn't require all the food or resources to get through, but it didn't turn out to be the case. So that tells us something about metabolism may not be the driver that we think it is through some of these extinctions, at least with respect to bivalves. I can't quite say what's going on with mammals or fish or any of the other clades, at least not right now. But great question.
Meaghan Cuddy:
Yeah, that is a really interesting question and answer. Peri, we've got one more question for you, kind of related to something that Stewart actually alluded to in his question. Are these cooperating males in manakins closely related to each other or related in some way?
Peri Bolton:
So these manakin males are not related. So we know this by taking genetic samples, and we can then look at the different genetic variance in our genetic samples and say, "Well, these ones share these variants and these ones don't," and that can tell us about whether they're related or not. So we've used that to infer that these guys that are cooperating tend not to be related. And it seems to be the case with the blue manakins as well, from my understanding.
Naimah Muhammad:
Okay. So I have our final question, I think here, which is a question to all, so we have a bit of time to get to it. And the question is, it's really to inspire our audiences here and our younger audiences who might be in college or young professional audiences. And the question is, how did you all get interested in this field? What kind of classes or steps would you recommend to a young person if they wanted to follow in your footsteps? And Ingrid, I'll pass that to you first, and then Stewart and Peri, you can close us out.
Ingrid Rochon:
I was a biology undergrad and there was a Natural History Museum affiliated with my university on campus. And I had to get a student job to pay my way through college. And I was like, "I'm going to work there." And I liked it so much more than anything else I did that I just kept doing it. And I went on to get a master's in museum studies and have been working in collections continuously pretty much since the day I stepped foot in one for my first student job.
Stewart Edie:
Yeah. That's a great question. I've been curious for most of my life, I think about why there are so many different types of rocks and fossils. It's just been a passion or a curiosity since I was pretty young. So when I got to high school and college, I started taking classes in environmental science and in geology and I became hooked, not only because they were answering the questions I had ever since I was six, but because it required studying and using so many different types of science, like chemistry and biology and physics all at once. And I just absolutely loved that interdisciplinary nature to this particular discipline. So I guess I would just say go to museums, take classes that you want to take to try to answer the questions that you have. You can absolutely make a career out of it.
Peri Bolton:
I think I'm in a similar boat to Stewart. I've always been a bit of a nerd. I think from a young age I always wanted to be an ologist of some description, and so I guess it was almost inevitable that I ended up here. In terms of specific tips on how to get there is don't lose your enthusiasm, don't let the study get you down because the world is amazing. And depending on your age and where your career level is at, in undergrad, you can work with researchers and do volunteering and get a feel of how to do the research and what it's actually like. And then I guess if you really want to do it and go ahead, you go and do a master's and maybe your PhD and it's a lot of fun.
Naimah Muhammad:
Well, thank you all so much. And I think all of your stories have reflected that not only is the research in the field important, but also the research that happens behind the scenes with the collections and just the vast amount of information and these pieces of the puzzles that you're all putting together in different areas in different expertise. So the audience is here, I see a lot of thank yous for sharing the work you're all doing. So I do want to thank the three of you for this excellent talk and to the audience for joining us tonight.
And we also of course want to give a big thank you to Busboys and Poets, our amazing restaurant collaborator, and to our behind the scenes team who helped us sort through all the questions and help things run smoothly. And to our donors, volunteers and viewers like you, the audience. And finally, to all our partners who help us reach, educate and empower millions of people around the world and help inspire the next generation of scientists around the world today and every day, we thank you.
Meaghan Cuddy:
Yes. And while this is the last Science Café of this season, we do hope that you'll join us for our other programs over the summer. We'll put a link in the Q&A where you can find some more information about our upcoming programs and how to sign up for our weekly eNewsletter, which is the best way to stay informed for all of our upcoming programs, and to learn a little bit more about our museum's research and our exhibits.
Naimah Muhammad:
Yes. And after this webinar, and you will see a survey pop up on screen asking for some feedback about the program, and we would love if you could take a moment to respond to this because we do go through them and learn more about what you enjoyed, what you learned, and how we could improve. So thank you in advance for providing this input. And again, thank you to our participants, to the speakers, to the audience, to the team, and we look forward to seeing you soon.
Meaghan Cuddy:
Bye.
Naimah Muhammad:
Thanks everyone.
Meaghan Cuddy:
Thank you.
Naimah Muhammad:
Bye.
