JOHN FITZPATRICK: Good evening everybody. Thank you for coming out on this beautiful rainy October evening. Welcome to the third annual Paul C. Mundinger lecture-- distinguished lecture series. We are absolutely thrilled to have Ellen Ketterson with us this evening. I'll tell you about Ellen in a minute.
I just want to mention that I'm John Fitzpatrick. I'm director of the Cornell Lab of Ornithology. We are streaming this worldwide, so I wanted to mention to anybody who doesn't know this already that the Cornell Lab of Ornithology is a global hub for the study, and appreciation, and conservation of birds, located in beautiful Ithaca, New York, affiliated with Cornell University. We are on the Cornell campus tonight.
We're very grateful to the Mundinger family for establishing this lectureship series three years ago in honor of the late Paul Mundinger, who received his PhD here at Cornell in 1968, and then after some postdoc time went on to establish a lustrous career at Queens College studying animal behavior with particular emphasis on birdsong and the role of genetics in animal behavior. This lectureship was established to give us a chance once a year to bring in a distinguished colleague who is world renowned for studies in avian evolution, ecology, and especially animal behavior, birdsong, and in our case tonight, a combination of all of these things with a little physiology thrown in.
Ellen Ketterson received her undergraduate and graduate training at Indiana University and she did some time out on the West Coast, or near the West Coast, with the great Jim King, came back to Bowling Green State for a bit, and then returned to Indiana University where she continues to be today, now as a distinguished professor. And she's also the co-founder of the Environmental Resilience Institute at IU and as well as the Center for Integrative Study of Animal Behavior.
Dr. Ketterson is also affiliated with the neuroscience program at IU, the cognitive science program at the Kinsey Institute. She is also an affiliate professor in gender studies at Indiana University. She is an archetypal interdisciplinary biologist. She studies bird behavior and biology at a number of different scales, from the physiology to the whole organism life history theory. She is equally comfortable in the lab and in the field, studying birds in remote parts of their natural landscapes as well as in the cities of the US.
She has won a whole panel of awards. I'll read the birdie related ones most and in sequence. The Elliott Coues Award by the then American Ornithologists Union, now the AOS-- American Ornithological Society-- 1996. In 1998, she won the-- she was awarded the Margaret Morse Nice medal, which I'm sure felt especially gratifying for Ellen, Margaret Morse Nice being the great leader of the women in ornithology in the mid 20th century. She was awarded the Alden Miller Award by the Cooper Ornithological Society in 2014, the Career Award for Animal Behavior Society in 2018.
She is also a Fellow of the American Association of Arts and Sciences and of the American Association for the Advancement of Science. She is indeed a distinguished biologist-- a world renowned biologist. One of the most amazing features of her recent career is the production in 2013 of a movie associated, I think, with an NSF Award that she and her lab received. And this movie succeeded in making extraordinary the ordinary junco. And I'm quite confident that we'll be hearing a fair amount about that bird and how extraordinarily it is tonight. So please welcome Ellen Ketterson. Thank you.
ELLEN KETTERSON: Thank you. Thank you very much, John. That was lovely, Fitz. I think of him as John, even though I know that's not what people say. But in any case, thank you in both your names. And I wanted to say a word about Paul C Mundinger. I was an animal behavior bird student in 1972, I guess, and I was studying for my prelims. And I was studying bird song at that time.
And as it turned out, carrying around those heavy speakers and those heavy tape recorders of the day sent me off in another direction. But I did get to read about the American goldfinch, and the fact that the male and female American goldfinch, when they formed a pair in the spring, they had a swoopy little song and flight thing they did like that. And their calls converged, so that they sounded more like one another after they formed a pair than they had before.
And that memory of vocal behavior has stuck with me ever since. So when I heard that I'd have an opportunity to speak for this lecture, the goldfinch came to mind. And I never met Paul Mundinger, but he's in my head. So I'm proud to have an opportunity to speak in his name.
So I'd like to talk to you about juncos tonight. That's the bird that I study. But I'd like to put it in the context of environmental change. Many of us are seeing and looking for ways to relate the research we do to-- you can call it the climate crisis, you can call it global warming, you can call it environmental change. There's a lot going on. It's going on very, very fast.
And also, because I know I'm at Cornell, I am not the only person that heard that we have three billion fewer birds in the world than we did in 1970, when I was a graduate student. So those 50 years have seen a loss of nearly three billion birds, with no reason to think that it's going to stop unless we do something. So that's the last 50 years. Be very, very concerned about the next 50 years.
So many of the people I know who study birds, and other organisms, and ecosystems, and communities are much more cognizant of the potential connection between what they do, partly because, why did that bird just do that? I'm curious. But also because knowing why that bird just did that might give us an opportunity to help preserve birds. And that would be a marvelous thing, to think that you'd been on earth for a while and had a role to play in that.
So the environment is changing. And animal populations really don't have a lot of choices, right? They can stay in place, they can move to new places, they can change the way they behave, they can modify their behavior, or-- not much of a choice-- they can go extinct. So moving, behavior-- those are the options that are available. And I've long been interested in migratory behavior in birds. So there's a connection there that makes me want to help.
So the question is, can they do it fast enough? So as I'll show you, animals, birds, have been changing their distributions-- their geographic distributions-- over time for a long time. But the rate of environmental change is so great that we really don't know, except we have this clue for the three billion birds. We really don't know what mechanisms birds have and what opportunities are available to them to try to respond to environmental change. So we need to understand both the past history of avian populations and their distribution, where they've been in years prior to now.
And then my shtick is that if we understand the mechanisms of responding to environmental change, then we're in a much better position to try to predict what will happen next. And those predictions, I think, are very important to us. So the way populations move, the way they diverge from one another, has underlying behavioral and physiological mechanisms. And again, the more we know, perhaps, the better predictions we can make.
So my other stick is the dark-eyed junco. I started studying this bird when I was a graduate student. And it has kept my attention. Maybe I have a narrow attention range. But in any case, I love this bird. And you're looking at it here and see how beautiful it is, then perhaps you can get a feel for why it has held my attention, or other people's attention, for so long.
So junco's like your kind of quintessential north temperate songbird. I study them at Mountain Lake Biological Station in Virginia. So the landscape here is mountain tops in Appalachia with understory, because the bird is a bird of the understory. So males show up in the spring. And they establish a territory, and they sing. And the goal of the song is to attract a female.
And they'll do it a lot. You know, sort of six times an hour or whatever-- I'm sorry, a minute, until they finally find a female. But with good fortune, a female arrives on the scene. And then juncos, like so many other birds, will have a specific courtship way of approaching a potential mate. So they don't just do that long range song that I just played for you. But I'll do this again, because I think it really is kind of fascinating.
So they puff up their body. They spread their tail. They hunker down a little bit. And they do this thing that we call short range song, which is very complex and low amplitude. I'm not playing it at a low amplitude for you here, because I want you to be able to hear it. But it's kind of whispered, and maybe to be less likely to be detected in the forest by another male bird. That isn't something we've really pursued.
But it is certainly true that the song is long. It's quite complex, and it's particular to courtship. However, there are more than one female in the forest. And males have this tendency to court multiple females. But of course, that has consequences. So male male competition and female choice are key aspects of how pair formation takes place in the spring. And different attributes of different individuals can make predictions about what's likely to happen in the future. This guy gets-- you know, maybe it wasn't too late.
So here's the things I'd like to tell you. I'm going to tell you a little bit about the junco's scientific history. They all came from somewhere, and junco's been studied by people before me, for sure. A little bit about the junco's taxonomic and phylogenetic history. Some of the drivers of divergence. Juncos, for those of you who know them, know that they look really different from place to place. So something's going on, and why is it that they look so different?
One reason may be the mate choice that we just had a chance to observe. And another possibility may be when they reproduce, or whether they migrate. And then if I get that far, then I'll finish up with some recent work on how juncos and other species are occupying urban environments, which is one of the forms of environmental change that some are able-- some bird species are able to adjust to and others are not.
So rich scientific history on the part of juncos. One is a taxonomic history. This is a man named Alden Miller. He was the director of the Museum of Vertebrate Zoology at Berkeley. And he was a serious collector of birds for his museum, including 10,000 juncos over the time. We see Alden Miller here with his gun-- his collecting gun-- and his basket-- you know, sorry-- here beside him.
And he wrote a monograph on the junco called Speciation in the Avian Genus Junco. He didn't live all that long, unfortunately. Died of 59. Much, much respected man. Made huge contributions to environmental and evolutionary biology.
So Ernst Mayr was maybe the premier evolutionary biologist of the last century. Certainly when it comes to birds, he would have been the premier evolutionary biologist. And when Alden Miller died, Ernst Mayr wrote an obituary for him. And this sentence comes from the obituary. So Mayr wrote, "Miller proved conclusively that geographic races in the junco--" that we're about to meet-- "are incipient species--" as in, species under formation-- "and show indeed such a perfect transition from local race to full species that to this date, 1972, there is not yet unanimity among ornithologists as to which group of populations should be considered species and which should could be should be considered subspecies."
And I'm here to tell you that this is 2019 and there's still not unanimity among ornithologists in terms of what groups of populations should be considered subspecies or species. So that's intriguing. And that part of what ties me to the junco is to be intrigued about this by this question.
But another important historical figure in the study of seasonal timing and organismal biology also studied the junco. And this is a photograph of William Rowan. And William Rowan came from Switzerland and emigrated to Canada. He was at the University of Alberta. And he was interested in the physiology and in migration and what tells a bird when to migrate. And the thought at the time was that birds pay attention to whether it's cold in the fall, so you migrate south, or it's warm in the spring, so you migrate north.
And he suspected that that wasn't really the right answer for how a bird knew what to do when. So he had this suspicion that in fact it had to do with how long the days were, because that's the other thing that changes over the course of the year, of course-- that the days get longer in the spring. And so to this appointment of his chairman, he went ahead and studied this question in juncos. The chairman thinking, you should be doing something biomedical. You should not be doing something that has to do with birds and field and not very important.
So he took the juncos that he caught in Canada into his backyard and had a garage like situation. And had one set of juncos that went through the normal increase in day length as the spring progressed, and another group of juncos that had a light bulb. So starting in December, there was a light bulb in their room. And then he compared the two. And being a man of the time, after he compared to two and found that the ones that had the longer light because of the light bulb were singing far sooner than the others, and he let them go, and they left. And he pulled out a subset, and they had larger gonads.
So the day length is what the cue had been for the juncos to decide when. And then, that's not just juncos, of course. Day length and photo period are very, very important cues in timing events of the annual cycle for all kinds of birds. But for me, [INAUDIBLE] the junco was the first bird in which photoperiodism was demonstrated. So juncos are and have responded to environmental change. And I'd like to tell you a little bit about that.
This is the current distribution, thanks to the breeding bird survey data. Each of those dots is a breeding bird survey result. And what you can see is that there are juncos down the Appalachians, in North Eastern North America, across the [INAUDIBLE], down the West Coast, and up into Alaska. So currently, this is the breeding distribution of juncos. They're breeding in boreal forest-like situations-- high altitude or high latitude.
But that wasn't always the case, because we know that we had glaciers. We know that there was a period of time when much of North America was covered with ice. And in fact, the last glacial maximum was about 14,000 years ago. And I live in Indiana. And the ice got almost to Bloomington, Indiana where I live at that latest time.
So if you do something called niche modeling or species distribution modeling and take the present day climatic requirements or attributes of a species, and say where were those climatic conditions 14,000 years ago. And if we're willing to think that the bird itself hasn't changed in the meantime, then if it was around, that's where it should have been. And so this slide shows us on the right that during the last glacial maximum, juncos were along the Gulf Coast. So they were down into Mexico and up along the West Coast, as well.
So what we can conclude from that, of course, is that they are now all over where I showed you the breeding bird survey data, but they weren't there then. So in the last 14,000 years, these birds have moved north and repopulated areas that were uninhabitable at the time. Juncos are cool. One reason they're cool is because they look so different from place to place.
So there are juncos down in Costa Rica. This thing probably is not visible. I'm going to tell you about the juncos that are up here, where we live, all right? Here in New York, they're in the Adirondacks. You would find the one on the far right, slate color juncos would be nesting. These are the maps are showing the breeding distributions of present day juncos.
In South Dakota in the Black Hills, you'd find white winged jungles. They look very much like the slate colored, but they have little white stripes on their wings. Down on the east side of the Rockies, you might see red back juncos, or gray headed jungles, or pink sided junkers. And then on the west side of the Rockies, there are these Oregon juncos that, as you can see, have black heads and orangey sides.
So those birds look different enough from one another that you might think you were looking at six or 12 species. I mean, that's-- when we look in a field guide, we don't usually see-- we can see things that look a lot more similar to one another than this, and not be told they're the same species. But juncos hybridize where these breeding ranges abutt. So if your definition of a species is the biological species concept of birds that hybridize with one another, birds that breed with one another, can't-- have to be the same species.
And juncos do that where they encounter one another. So they have distinct breeding distributions. But they don't have barriers to gene flow that are strong enough to prevent them crossing with one another. So six forms, but one species, if we use the biological species concept. But those forms are all genetically distinct, even if they hybridize.
So if you just want to say, well, can I tell them apart? Genetically, are they sufficiently distinct to be a lineage that's recognizable? Then the answer is yes. So for these lovely little colors-- and let me say quickly, this is work done by Borja Mila, who is a evolutionary phylogenetic person that we've worked with over the years. So the top one is this light color, and then the white wing, and then the Oregon, and then the pink sided, and on down.
So these bars across are portraying genetic continuity within the bar. And the little division lines indicate when they separated from one another in historical time. The point to carry away is that only have juncos reoccupied the eastern and continental US since the last glacial maximum, but they've also diverged from one another in that same amount of time. So they are very recently diverged.
And these striking plumage differences, they're similar enough to still interbreed where they meet up with one another. But you can look at single nucleotide polymorphisms and tell one group from another. So that's part of the mystery. How did they get to be so different from one another, looks so different from one another, so rapidly? Maybe it was all about the plumage change. Maybe the mate choice that we saw early in my little talk here gave rise to the opportunity to see this separation in the different types.
So imagine them coming back up after the last glacial maximum, and the ice is retreating, and they're in mountains or areas that are distinct from one another. And then these plumage differences arise, and females show a preference that becomes ingrained in one breeding population or another. And that would be the pretty much standard story. And in fact, Borja Mila, my colleague, says that's it, Ellen. There's really nothing else to add. That's the answer how they came to be looking so different from another in such a short period of time.
But because I'm interested in migration, I have stuck with the idea that maybe we should consider alternate explanations, as well. So perhaps the rapid change in the environment that occurred over those 14,000 years gave rise to a situation where some were migrating and some weren't, and some were breeding at one time of the year and others were not, and that natural selection played a role in giving rise to the differences between these groups. Or when I get to the end, I'm going to say maybe both. We can see.
So this slide is about the feather differences between the Oregon junco, which is the far west one, and the slate color junco, which is on the far east. And I'm showing you what the feathers look like under a microscope. And then I'm showing you the pigment that determines how the feathers differ in color. And then I'm going to conclude by telling you that the genes that give rise to these pigments that account for the color really don't differ in essential ways between the Oregon junco and the slate colored junco. They simply differ and which ones are turned on in which feathers and which ones are turned off so.
These pigments are getting kind of shuffled among feather tracts without actually having an underlying genetic source of variation. So I don't know for sure, really, how well you all can see in here. If you look in the upper two squares, the one on the right is the slate colored. The one on the left is the Oregon. And the firm part, the center of the feather, is called the rachis. And the things that come off the side of the feather are called the barbs. And then, the little things that come together from the barbs are called the bar barbules.
And the point I want to make about the upper two feathers is that in the case of the slate colored junco, the barb is white. So the rachis is black and the barbules are black where they meet each other. But the barb itself is white. So melanin is being produced in the rachis and in the barbules, but there's no melanin being produced in the barbs.
That's not true of the black headed Oregon junco. So you've got a feather here where part of it is lacking melanin. And the collective effect of it is that you look at it and you see gray in one case and you see black in the other case. For the back, and the flank, and the ventral, there's similar sorts of things. Both have white bellies, so there's just no melanin being made at all in the belly feathers. And then, for the Oregon and the slate color, they differ in whether or not they've got the brown pigment, called a pheomelanin. And that's much more present in the Oregon junco than it is in the slate colored junco.
So you can get a gray head or a black head simply by leaving melanin out of just a portion of the feather, but not whole feathers. And importantly, when you pluck those growing feathers and you pull out the little pulp, and then the feather grows back, and take the tissue in the base of the feather, and check on it for what the genes are being expressed, then you find that there's variation in gene expression for the enzymes that have to do with melanin production, but not in the gene sequences, as I told you.
So the variation is really just skin deep when it comes to color, even though it looks so different to us. And maybe that's the basis for mate choice. We don't have the information on that. So we know kind of sequence-wise and expression-wise why they look different from place to place, but we don't know that that's what has driven the variation in the different subspecies.
So we're going to switch to seasonal variation and migration. So we know that as the year goes around, trees lose their leaves, turn color, whatever, and that the same is true of birds. So in the spring, the gonads grow. In the summer, males and females form a pair, and they raise their offspring. In the autumn, they change their feathers, they molt, and they migrate south after they put on a little fat. Make it through the winter and start the whole cycle again.
So those are the events of the annual cycle, but the timing of the annual cycle is obviously important, as well. And we know there's geographic variation among species in when various things happen. So here's a couple of bald eagles. And the one on the top is in Florida. And it's building its nest and being parental in December. And the one on the bottom, you can just see the head. That's the head of the eagle coming with the snow all over her back.
And so in March, in Pennsylvania, if you decide to be parental and build your nest, you may have to encounter harsher conditions. So environmental change is advancing timing of events of the annual cycle. I saw a paper today with almost all of the species that had been looked at were laying their eggs earlier in the year. And in birds, then, we are also seeing earlier breeding and some loss of migration. So species that were formerly migrating have settled down to be residents and are not moving around to the same degree.
So reproductive timing can influence the opportunity for gene flow. We're trying to understand how juncos could get to be so different from one another so rapidly. So the differences in timing and reproduction among populations has a word for it, has a name. It's called allochrony. And that can serve as a barrier to gene flow. There are examples of allochrony or timing differences that give rise to new species.
And so apple maggot flies, the fruits that they lay their eggs on mature at different times. So even though they're living in the same place, they aren't crossing with one another. And so you can get speciation in a backyard. Flowers that bloom at different times, you may be in the same field, so you're all in the same place. But some may be blooming early and some may be blooming later. And so the pollinators don't really transfer pollen from one to another.
Cicadas are similar. Storm petrels, since we're in a bird thing, will arrive at an island to breed, but one arrives in the spring and one arrives in the fall. So they don't encounter one another. And we're seeing speciation as a function of differences in timing. So a little bit more on how migration can serve as a barrier to gene flow.
I want to talk about sympatric-- populations that live together. That's what sympatric means. Allopatric-- populations that live apart. And we're using an indigo bunting here as an example. And just as an insert, I saw today that we have many fewer indigo buntings than we did 50 years ago. Numbers are declining. It's a beautiful bird, of course. And if you know the bird, then you know that it turns bright blue for the summer months, but it's kind of a drab brown in between.
So the winter populations in this hypothetical of indigo buntings are brown and living together. The spring comes, and one is migratory and one isn't. So the column on the left is the migratory group, and the column on the right is the resident group. So you can see that the resident has turned bright blue, but the migrant is still brown, because it hasn't taken off yet. And then, reproductive and migratory timing can create barriers. So the fact that the migrant is slower to be prepared to reproduce means that that's a barrier to gene flow.
And the fact that the migrants migrate means that, then, later in their different places, so they're not mating with each other. However, let's speculate that migration ceases, as we know is happening in some situations. And in that case, the migrants and the residence may begin to breed with one another. And then they'll get hybrids and then selection. We'll see whether that's good for the hybrids or not.
In those cases, then, if the migrants stop migrating and start breeding earlier, then a situation that formerly prevented gene flow or breeding between the migrants and the residents has now disappeared. So they're exchanging genes because of the change in timing that goes along with the change in migratory behavior.
So this situation of being seen sympatric in the winter and allopatric when breeding, living together, and then living apart after the migratory group leaves is characteristic of juncos. And we've been taking advantage, I guess, of that situation that in the spring, the migrants and residents are living together. They're eating together, they're flocking together, they're hearing each other. But one hasn't left, and the other is proceeding to reproduce.
And that happens both in the Appalachians, where there's a migrant and a resonant group. It happens in Colorado, where there are different subspecies, where they winter together-- pink sided, gray heads, white winged juncos, Oregon juncos, slate color juncos all wintering together. I'll show you in a second. And then in Southern California, we have situations where birds are ceasing to migrate and, again, overlapping with other species.
So this slide is some juncos feeding on the ground in Denver, Colorado in the winter. And I hope the lights are good in here so you can see that they look quite different from one another. And so in the same flock, eating the same food, altogether here is the gray headed junco. Here's a slate color junco. Here's an Oregon junco. And here's a pink side junco. Are those colors showing up for you all? Are they-- OK. Looking from the slide, I can't tell. Sorry. I just want-- they're not. OK.
Point being, these are a group of subspecies that are sympatric in the winter, but they're going different places. So we've been studying this in Virginia, in the Appalachians, where there's a resident subspecies called the Carolina junco and a migratory species, the slate colored jungle. And in the spring, we'll go and we'll sample them both in the field, and then bring them into captivity. And the question is, how different are they fixed in their differences of whether they migrate and whether they're not and their timing of reproduction?
So if you catch them in the winter, and take a blood sample, and say, who's got more testosterone than who else, then testosterone being a reflection of the gonads growing, the red is the residents and the blue is the migrants. So same date, same location, same day length, same food, but one group is elevating its testosterone and the other one is not. Maybe not likely gene flow in that situation.
We ask whether those differences are fixed and flexible. And the way to see if they're fixed or flexible is to bring them into what's called a common garden, or letting them be in the same place, and pursue what happens in the spring. So we capture them in Virginia. We bring them to Indiana. We put them in cages that are next to each other, and we let the day length increase naturally. And then we compare them to each other.
And the cloacal protuberance is a little structure on the cloaca of a bird that grows when its gonads are growing. So the gonads inside are producing the testosterone and producing the sperm. And then there's this outside structure, where the sperm gets stored before the event of copulation takes place. You don't have a big cloacal protuberance if you don't have a big gonad, and this is comparing cloacal protuberance of residents in the red and migrants in the blue in birds that were held in side by side cages indoors-- same day length, same food-- responding very differently as the day is increased in length over the spring.
On the other hand, the migrants-- same birds, same cages, whatever-- they were putting on fat. So fat is a predatory thing for migration. And when we look at the migrants, they're all blue and full of fat. And when we look at the residents, they have just much lower levels of fat. So we conclude, then, that these differences are relatively fixed and in a common garden. Now, we'd really like to know how fixed is fixed. Is that underlying genetic, or could that possibly be something that's developmentally induced by what the day length is where baby birds grow up?
So thus far, this common garden result would be what people usually say-- this is genetic divergence. And it relates to seasonal timing, and it has an impact for-- implication for who breeds with whom. But this coming spring, we're going to be taking the juncos that grow up at high latitudes in hot long days and putting them-- rearing them under shorter days, and taking the juncos that are ordinarily reared under shorter days and rearing them under longer days, and then see what they do the next year.
So it's possible, and there's some rodent studies to suggest. And that would have a big implication. So it's the science and we're interested in what it does. But if it really is a genetic divergence kind of a thing and it is quite fixed, then it's not going to change very rapidly. On the other hand, if it's developmentally determined by what your early exposure to a day length is, then it could change fairly rapidly. So that's why we think that mechanisms are important to understand if we're going to make good predictions about what's going to happen in the future.
This is our other cool result. I don't think it's the only cool result, but I think it is a cool result, which is what's being plotted here. The blue is, again, the migrants and the red is the residents. And the y-axis is how big a gonad a bird had in the late spring. So the bigger the gonad, the closer they are to reproduction. The thing that's novel that I haven't said before is what's on the x-axis.
And the x-axis as plotted here is stable isotopes-- water stable isotopes. Stable isotopes are hydrogen isotopes that reflect what the hydrogen ratio is in water that a bird is drinking when it grows its feathers. And hydrogen isotope ratios vary with latitude. So if you're growing your feather at a higher latitude, you're going to have a lighter feather. If you're growing your feather at a lower latitude, you're going to have a heavier feather.
And what you can see here in these data is the birds that came from the farther north, we only know them from their cages, but we pluck their feathers and look at their isotope ratio. And if it's really low, that says it's a high latitude bird. And if it's bigger-- not so light, if it's heavier-- then it's a bird that came from a higher latitude.
So what does this slide say? So what is says is, here I am in this cage and I have a long way to go in my migration. And so I am only going to have my gonad be really pretty small at this time, whereas if I am going to a place that's a little closer-- and I know it's closer, because I've got this kind of feather that says that the isotope ratio was heavier-- then I'm going to grow them sooner. And if I'm a resident, then I'm going to grow them soonest of all.
So the origin-- the latitude of origin-- of a bird reflects or plays a role in determining when it prepares to reproduce the following spring, even though it's not there yet, right? It's down there at a day length that is the wintering place. But it's adjusting its reproductive development to its destination. And it doesn't make any heavy gonad any sooner than it needs it.
OK. This has all been males. So let me tell you a little bit about females. These are some comparisons of the ovary mass of female residents and female migrants in Virginia. So the red, again, is residents and the blue is migrants. And what you see is when these birds were taken on the same day, the residents had a bigger ovary. And with respect to the stable isotope thing among the migrants, the females that had the biggest ovary were the ones that had come from nearby. And the ones that had the smallest ovary had the farthest to go.
So males and females are gauging their reproductive development to match when it's likely to become suitable to breed at the place that they're heading back to. So this sounds like seasonal timing could make a difference. And if you don't even get ready to breed, you're not likely to be exchanging genes with somebody else. But it doesn't suggest a categorical difference, like residents are this way and migrants are that way in an area that's [INAUDIBLE]
It seems like you could disperse a little farther north or disperse a little farther south and not really be breeding with someone that was not a suitable mate. So it doesn't really suggest to me that seasonal timing is the first step. Or it may be a first step, but it's certainly not a reflection currently of speciation in action. But we can go a little bit back to the mate choice question.
And the same person who was looking at the females and looking at the ovaries was also saying, well, is there any more choice going on here? And this was Abby [? Kimit ?] and she was a graduate student. So she presented male juncos in Virginia with female migrants and female residents and asked whether they could tell the difference. And this little video is of a male-- not the cartoon that I showed you earlier, but a male who is in film. If I can find the thing. Yeah, here we go. Well, I think I can.
Can you see how close I am but not making it? There's his little short range song. And he's excited, and he's puffed up. He's picking up a little bit of grass and showing it to her. She's not doing much. I understand, she's not doing much. Males do get excited when they see females in the middle of their territory. Yeah. Cute guy. I would have taken him, but she wasn't paying much attention.
So when you put it into data form, this is Abby's data saying how much attention did the male residents pay to the female migrants versus the female residents. And the female residents in that little one bird trial kind of thing got more attention from the males than did the migrant females. So that could be that they look a little bit different. The residents have blue bills and they're a little bit bigger. And they're not quite so melanistic. Their feathers aren't quite so dark.
But it could also be that the migrants-- females are not sufficiently reproductively ready. So they're not giving off signals of having their ovaries grown. And then you go, well, what kind of signal could be that? I mean, it could be just showing some interest back again, or it could be some kind of odor. So until recently, I think the generalization has been birds don't smell. But in fact, birds are emitting volatile compounds from their preened glands.
And males may be picking up on scent cues-- we don't know this yet. This would be for the future. Scent cues that would say, eh, she's not ready to reproduce. I'm not going to court her. OK. So summarizing some of what I've told you, since the last glacial maximum 15,000 years ago, juncos have diverged to sub-specific status, and we could argue about subspecies. And we don't have to.
Plumage differences persist in a common environment. Those feathers that were plucked to see what the genes were that were being expressed in the growing feather, those birds were living in the same environment when they were picked. But they don't differentiate gene sequence. Even though they look so different, they differ in the expression of the genes. Timing differences do persist in a common environment, and more mechanisms are under study.
So we have some limited evidence for mate choice and sympatry. And which came first? You know the mate choice and then the timing, or the timing and then the mate choice, or maybe they're both important. I could use help with that. So if there's people in the audience who say, I could help you sort through those things. I know that it would be my choice first followed by timing differences. And someone else might say, oh, I don't think so. I think you get timing differences.
The really kind of cool potential idea is what if that made choice is occurring in sympatry. So usually, the story would be those breeding ranges are separate from one another. So they're allopatric, so chance gives rise to plumage variance. And you know, females develop a preference for one kind of plumage coloration. And that's how they became different from one other in isolation. The other possibility-- and it is a possibility-- is that they became different from one another in sympatry, because those plumage differences are signaling where they're headed. Those plumage differences are potentially saying, I'm an early breeder and I breed right here. I'm a late breeder. I'm headed off to Wyoming. I'm a really late breeder. I'm headed off to Alaska.
And that's something that people who are interested in migration and population divergence and speciation just starting to talk about. And it's not, as I say, the usual way of thinking about it. So I don't want to keep you too long. Let's see. How much time am I allowed? I'm allowed a little more time. OK. Thank you for listening.
Another cool thing that juncos have done is adapt to urban environments. So about 30 years ago-- but when people started studying it, it was only about 10 years ago-- they were juncos in San Diego that ceased migrating. And there had been no juncos breeding in the city of San Diego prior to that time. Many expert bird people would testify that there had been no breeding juncos in San Diego.
Juncos are right now in the process of spreading to a whole lot of places. So they're breeding in Cleveland when they didn't before. They're breeding on the Channel Islands. Somebody I was talking with-- but at the time, there hadn't been any juncos breeding. And this was now about 30 years ago. And a guy named Trevor Price, who's an evolutionary biologist and study birds now currently at the University of Chicago, and a student of his, Pamela Yeh, said, whoa, this is an opportunity to study divergence in action. This is a opportunity to study how populations are accommodating urban environments. And let's see if they're different from one another, and answering that question of how fast might they be able to become different.
So I'm going to rush you through some comparisons of juncos living in the city of San Diego with juncos that didn't settle in the city and live nearby in the mountains of Southern California. And so we compared them today to see whether they might still be evolving. So they look different in their plumage. The ones that join the city have a little less white in their tail. They have a little more brown on their crowns. They're a little bit smaller in their wing length. So there's some morphological differences that arose really quickly.
And you put them in a common garden, and they persist, so even though it happened in only about 10 years. The city birds are less aggressive than the mountain birds. So you can do simulated territorial intrusions and see how rapidly birds will exhibit aggression towards an intruder. And the birds in the city-- less aggressive. The birds in the city have fewer extra-pair fertilization. So the extra-pair fertilization rate is higher in the non-urban birds than it is in the urban birds. And you're becoming familiar with how male juncos behave when they're interested in females.
Corticosterone, which is a hormone that's produced in response to stressors and in handling and things, and the birds that were not in the city were more stressed by handling than the birds that lived in the city. So the city birds were calmer, less aggressive, fewer extra-pair fertilization, closer approach-- which might not be surprising, but was shown to be true.
And for the Mundinger lecture, I wanted to have a little bit of bird song in here. So one thing that also differs between the birds in the city and other birds-- and this has been seen in other species, as well-- is that the frequency of their vocalization-- how high pitched or low pitched it is-- it varies in the city. And the birds in the city sing at a slightly higher pitch. And the explanation is that there's all this background noise-- buses, and cars, and people, and whatever.
But it's interesting to see. And if I don't take you too many minutes here, this is a-- I'm not too good with this. Let's see if I can get a song faster this time. So you're familiar with this junco song now. But if we compare junco songs from the city and from a non-urban situation, there's two graphs here of what a song looks like when you do a spectrogram of that auditory signal that we just saw. And in the upper one-- and then we've got little syllables in the song. And in the upper one, they're the same. You know, you look it up one syllable within the long song, and they look the same if they're urban or not.
But in the lower one, we can see that one bird has pitched its syllables somewhat higher. Those are the city birds, as opposed to the ones that are living in a non-urban situation. And that's maintained in a common garden. So you bring those birds back, and you rear them in an aviary kind of setting. And that difference in the frequency of their songs persists in a common garden.
So at the time, it was like only 10 or 15 years, and you have these plumage differences-- all these differences that were related, in fact, to testosterone and the like, and happening in almost no time. So the story has collectively some impressions of the adaptability of birds, their capacity to make rapid changes. But not for everybody, and not right away. And time would be required for other kinds of changes.
So animal populations can move, they can modify how they behave, or they can die. Can they do it fast enough? Juncos have kept up in the past. We've seen that with the movement north from the last glacial maximum. The current pace of change in the environment is very rapid, but we need more. It's always ends with we need more research. But we really do, you all. We need to know more if we're going to be able to make accurate predictions about what's going to happen in the future.
So I hope you like juncos. I've worked with some amazing people. Here are some of their photos. And I could show you just a few seconds of our ordinary extraordinary junco film, and then would be happy to answer any questions if you have them. So let's see. So this is a long film-- 88 minutes. You don't have to--
- In 2012, biologists from around the world met at Indiana University to chart the course of future research on the junco. Since Rowan's pioneering discovery of photoperiodism in the 1920s, juncos have played a starring role in groundbreaking discoveries from a remarkable array of biological disciplines. From Ellen Ketterson's long term research on testosterone and social behavior, to Borja Mila's continued quest to understand their spectacular diversification across the continent, to ongoing studies in San Diego where they're evolving right before our eyes, juncos continue to teach us important lessons about the natural world.
- It's a very exciting time to be an evolutionary biologist right now, because we're just now being able to link some of the physical aspects we see about organisms, about birds, such as their plumage, their morphology, even their behavior to specific genes. Up until now, it's been very difficult to actually isolate genes, because really it's looking for a needle in a haystack.
The size of the genome is so large, and these individual genes are so small that it's been very difficult to zero in on them. Now, with new sequencing technologies, what we're being able to do is sort through more and more of that haystack to find the needle. But now, we can look at the entire genome. And the difference between that is probably about a million times what we could do before in the same amount of times.
- Despite nearly 100 years of intensive research on the junco, there's no end in sight to what we can learn through studying this amazing group of birds.
- Hi. My name is Trevor. We can learn a lot about how to live in the city from the junco.
- We can learn about speciation from the junco.
- Climate change.
- The brain.
- We can learn a lot about violence from the junco.
- How genes affect behavior.
- We can learn a lot about mate choice.
- Gene expression.
- Range expansions.
- We can learn a lot about maternal care from the junco.
- And geographical variation.
- We can learn a lot about sex, food, and death.
- Sensory systems.
- Trait selection.
- We can learn a lot about disease ecology.
- We can learn a lot about beauty and nature from the junco.
- So the next time you see a little gray bird, maybe even in your own backyard, remember to take a second look and consider all that can be learned from the ordinary extraordinary junco.
ELLEN KETTERSON: Thank you. That was very warm. Appreciate it. Any questions? Yes.
AUDIENCE: I was wondering if you could show the slide of the divergence of [INAUDIBLE]. It looked like there's two different lineages of Oregon juncos. So how would that happen if they had different [INAUDIBLE] types [INAUDIBLE]
ELLEN KETTERSON: Right. So we're talking about the slide that has all the pretty slide colors going like that. And it is true that Alden Miller, our 100 years ago biologist, had the Oregon juncos divided into more nameable groups. So there are plumage variance within the Oregon junco that have a geographic distribution along the West Coast. And as it turns out, as extraordinary as it is to us-- those of us who didn't have single nucleotide polymorphisms to detect population structure-- you can tell a junco-- there's structure in the junco populations from northern California to middle California to southern California.
So they are divergent enough to be clustering differently. And that's why they got their own colored line in that slide. Did I answer your question? OK. Sure.
AUDIENCE: OK, so then what about the [INAUDIBLE] to British Columbia?
ELLEN KETTERSON: Yeah.
AUDIENCE: So it's just California or [INAUDIBLE]
ELLEN KETTERSON: No. I think, actually, it does include British Columbia. And I was sort of doing a California north, middle, and south. But, you know, it goes on up there. So there's Montana, some [INAUDIBLE], and on and on. But to be detectable-- Borja Mila, this guy-- before we had single nucleotide polymorphisms, what we had with mitochondrial DNA. And if you use mitochondrial DNA, you can't tell any of these northern forms apart. So they're sufficiently similar genetically at using that tool not to be able to see which group diverged from which other group at what time.
But now, with the new genotype by sequencing, it's possible. And as Miller would have predicted-- sorry for that-- he could see plumage variance. And now there are genetic structures to parallel the plumage variance he saw. What's a species? You can still argue about what's a species. But you've got all of this population structure and meaning, genetically recognizable clusters of populations that can be detected. But yeah. Yes?
AUDIENCE: About that same slide, the assertion that 15,000 years ago-- maybe not the ones that still live in the tropical areas, but all of the ones that we know of [INAUDIBLE] all definitely came from one species only 15,000 years ago?
ELLEN KETTERSON: That's what Borja Mila says. That's what Borja Mila says. He says using a molecular clock, talking about the rate of accumulation of changes, it's doable within 15,000 years. Trevor Price, not so sure. Trevor Price says, well, you know, maybe there were glaciation advances, retreats, advances, retreats, and that those forms may be older than that. Borja Mila speaks back and says, I've got my clock. I've got my rate of change. I'm telling you that it's 10,000 to 15,000 years.
And I was talking to Peter just last night. And he was describing similar rates of divergence in the song sparrow. So I don't think we thought that until we had the tools, maybe, to see. But are you skeptical? Nope. Just curious. OK. Great.
JOHN FITZPATRICK: I was surprised--
ELLEN KETTERSON: Fitz.
JOHN FITZPATRICK: I was surprised to hear that the common garden experiment of two different voices in the city versus natural landscape. Those were persisting between generations, is that right?
ELLEN KETTERSON: Not between generations, but-- well, let me try.
JOHN FITZPATRICK: [INAUDIBLE]
ELLEN KETTERSON: They could be. We brought in juveniles, and juveniles differed from one another when they grew up the following spring and sang their songs. So if they had learned in the first few weeks before they were caught and brought back to Indiana, and that was the learning thing, then it still persisted in a common garden. But it wouldn't necessarily mean genetic divergence in song structure. Yeah. Thanks for asking. I'd like to have it clear. Yes.
AUDIENCE: Between the residents and the migrants and the difference in fat, was that due to increased feeding or was it some other--
ELLEN KETTERSON: Right. So the question is the migrants were much fatter than the residents when they were living in the same environment, and was that because they-- presumably, they ate more. They had the same food, but they have a motivation to feed that is greater than it is in the residents. And so the consequence of hyperphagia, which is what the physiologists call it-- you know, hyper as in bigger, and phagia as in eating. But they-- a migrant bird becomes hyperphagiac when it's preparing to migrate. So they choose to eat more in the same situation compared to their neighbors who don't choose to. So they get fat and the other guys don't. Yes?
AUDIENCE: Referring to the slide that discussed the male preference resident versus migratory females, there was certainly visible difference. But there was a fair bit of [INAUDIBLE]. But I was just wondering, does that thing make any functional difference that allows more cross-breeding, that would be actually related to successful offspring? Or does the fact that there's no [INAUDIBLE] make them [INAUDIBLE]
ELLEN KETTERSON: Right. Let me make sure I do understand. So this is the slide where the males showed a certain amount of attention-- courtship attention-- to-- resident males to other resident females versus resident males towards migrant females. And while there was a difference in the means and the blocks of red and blue look quite different, there was a lot of variation. And that is true. There was a lot of variation. The sample size was not terribly large. So I don't think we can go so far as you were suggesting to say that because there's a lot of variation, there might be hybridization. I think that would be premature. Not necessarily wrong, just not a conclusion that you can make.
Yeah. I think you just couldn't make that conclusion from that slide. But that's the kind of question that we're trying to address. Yeah. Yes, Steve?
AUDIENCE: [INAUDIBLE] experiment where you're giving the male and female, [INAUDIBLE]
You could modify by sort of changing the [INAUDIBLE] on your resident migrants, so they're in similar states as [INAUDIBLE] difference [INAUDIBLE]
ELLEN KETTERSON: Yeah. OK. So that's a great suggestion. So we know-- actually that was-- the study was done in the field, so it wasn't a common garden study. But to the degree that we saw an effect, the resident males were preferring resident females over migrant females. But as we said, the migrant females were not as developed reproductively. So I think Steve's suggestion is, why don't you bring them in, give them some longer days, then put them out and see whether if they've been exposed to long days, they're equally attractive to the resident males. Yeah.
And Abby wanted to do that. She tried doing it in captivity, and they wouldn't choose. So she-- you know, she took females and did just what you suggested. Had females that had been put under longer days to try to accelerate the development in the migrant females to see if she could reduce the choice or that it-- or it would turn out to be because they looked different and not because they were in different reproductive state. So it's the right experiment. We haven't been able to succeed at doing it right.
AUDIENCE: It could also be with the male. [INAUDIBLE] to change them. So the male is in a different state, and the females are still different. Then see where--
ELLEN KETTERSON: Yeah. And we never even-- it's a good idea, and we never even did think to do that. So because we've only asked about male choice for females of the two different types. But yeah. Nice idea. OK. Yes?
AUDIENCE: Are there dialect variations among the [INAUDIBLE] phenotype variation [INAUDIBLE]?
ELLEN KETTERSON: I'm sorry, I missed one word.
AUDIENCE: Are there dialect--
ELLEN KETTERSON: Oh, dialect. OK. So I have the same student, Dustin [INAUDIBLE] who is part of the song study that I showed you, also has compared long range song. And this is not going to be satisfying answer when we get to the end, because we don't know it yet enough. But he's compared long range song-- the advertising song-- geographically, and then also this courtship complex song. And he does not find detectable differences in the advertising, or the long range song. He doesn't know yet about the short range song, which is where you would expect to see the divergence and have it be meaningful if it exists.
I don't have the answer for you yet. He's got all the tapes. Anybody here who does tapes or sound files knows that there's a gap between when you get them and when you know the answer, particularly for very complex vocalizations like that. But it's a great question. And we've been focusing on the visual differences, but-- oh, that's Pamela Yeh. So I didn't realize the movie was still running in the background. So yeah, this is the San Diego module of the Ordinary Extraordinary Junco, which is available on Vimeo. Anybody can watch it free. Show it to your classroom. Yes?
AUDIENCE: Are the city, urbanized juncos nesting in different places than the ones [INAUDIBLE]
ELLEN KETTERSON: OK. So the question was are urban juncos using different nest sites than the rural juncos. And I think yes and no. If you've ever been to San Diego and the UCSD campus, you know there's this big thing. And they were nesting and ivy and stuff. Jungles are quite variable in what they'll do. So yes, it may look like they're in a few more plantings on the campus than they are in the rural setting, but I don't think that is an indicator of their having a different view of what makes a good nest site, because they're quite diverse in their nest site choices-- like bike helmets. I don't think there's been selection for nesting in a bike helmet, but there was a nest in a bike helmet on the campus. Yeah.
Well you're a great aud-- yes, Ned?
AUDIENCE: [INAUDIBLE] some migrant males that have that enlarged gonad?
ELLEN KETTERSON: Mm-hmm.
AUDIENCE Have you seen instances of individuals that have shifted themselves from being a migrant to staying a resident from one year to the next?
ELLEN KETTERSON: Yeah, I haven't. You know, I would be fascinated to know. I can tell you that that relationship between gonad size or testosterone response to gender, age, or other sorts of things-- we've replicated that a couple more times. And you've been so patient, I don't want to keep you too long. Let me just say this one, too. In Denver, where the pink sided juncos and the gray headed juncos winter together, and then the gray headed juncos go about this far and the pink side of juncos go about that far. And they, too, are showing a size of the gonad in relation to how far away their destination is.
So it's a robust general finding, but there's variation among individuals that leads me to understand why you would be asking the question might they be shifting back and forth. We don't have that fine grained knowledge to be able to answer that question. Is it OK for me to keep answering questions? One more. OK. Yes?
AUDIENCE: Actually just in the video showing the life and time frame where they are nesting, they were showing [INAUDIBLE] much larger. [INAUDIBLE]
ELLEN KETTERSON: I'm not totally sure what you saw. Is it comparing when the urban juncos reproduce as compared to when the rural juncos reproduce? OK. So yes, another difference between living in the city is that they begin breeding earlier. And they breed for longer. So they can have up to four broods in the city. And two would be unusual up in the nearby mountains.
So there's lots to explain, and this timing seems to be a very important issue. And it's pretty flexible in that case. And I didn't tell you this but, for the urban and the rural juncos, when we put them in the common garden, they didn't stay different. So they're recently enough evolved, or diverged, or separate that-- I couldn't show you everything, but that conforms to what we might predict, is that they have only recently separated from one another, and they were not different from each other in their timing in the common garden. Yeah.
ELLEN KETTERSON: OK.
We've received your request
You will be notified by email when the transcript and captions are available. The process may take up to 5 business days. Please contact email@example.com if you have any questions about this request.
When animal populations are impacted by human-caused changes, they are forced to move to new places, modify how they behave, or face extinction. Dr. Ellen D. Ketterson, professor of biology at Indiana University Bloomington, addresses our need as invested citizens to understand animal migration and seasonality in relation to biodiversity.
Ketterson will examine the very real implications of our changing world through the lens of the dark-eyed junco, a model bird species commonly known as the snowbird. Focusing on the causes and consequences of environmental change helps equip humans to predict future responses and champion the biodiversity that makes our planet so amazing.
This event is part of the Paul C. Mundinger Distinguished Lectureship series, established in honor of the late Paul Mundinger, who received his Ph.D. in Evolutionary Biology from Cornell.