179- Michael Branstetter - The deep history of the mason bees


Speaker 1: From the Oregon State University Extension Service, this is Pollination, a podcast that tells the stories of researchers, land managers, and concerned citizens making bold strides to improve the health of pollinators.

I'm your host, Dr. Adoni Melopoulos, assistant professor in pollinator health in the department of horticulture. One of my favorite times of year is mason bee season. It's with this beautiful blue metallic bee, Osmeolichneria, if you're in Washington or Utah or California, is out foraging. It's one of the first bees that we see. And for many of you, you've got straws or some kind of wooden block where these bees are nesting, providing not only pollination, but a lot of delight to you to watch these really gregarious and hardworking bees at work. Now, we've had previous episodes where we've learned there are other Osmeolichneria and to help us sort this all out and get the picture of the Osmeolichneria and the subgenus Osmeolichneria is classified, I reached out to Dr. Michael Brandstetter, who is a research entomologist at the USDA, ARS, Pollinating Insects Research Unit in Logan, Utah. Now, he specializes in understanding the deep history of these bees using DNA technology or molecular systematics.

And in this episode, he's going to tell us about what he found when he looked at this group. And there's some very remarkable discoveries in terms of where this bee came from, its evolutionary history, and some important insights into the management of these bees based on their evolutionary history. So without further ado, Dr. Michael Brandstetter, this week on Pollination.

Well, welcome to Pollination. I'm so glad to have you on the show. Yeah, thank you. It's great to be here. You know, I remember the first time I met you, it was an Orchard Bee Association meeting. It was a coffee break and you studiously got to work on some data that you were working on.

And it was a very complicated screen that you had in front of you. And I imagine this pursuit of learning the evolutionary biology of insects and bees, in this case, is a very specialized skill set. So to begin with, what has inspired you to spend your career working on these kinds of questions?

Speaker 2: Yeah, well, I mean, sort of just studying the natural history of organisms on the planet, it's just something that has always been of a great interest of mine, which has fascinated me in understanding their evolution.

And especially, you know, just these interesting cases of, you know, convergence, you know, or unexpected things, you know, kind of just, you know, figuring, you know, defining those things and discovering them has always just fascinated me. And figuring out what you can sort of reconstruct by just looking at, you know, the species that exist today. So reconstructing, you know, maybe what happened in the past to help us explain, you know, the patterns of diversity that we see today.

And, you know, for a long time, you know, we just looked at, you know, the morphology of insects and, you know, both living things as well as fossils to sort of try to piece together, you know, sort of observe, you know, document the patterns and then try to explain, you know, those patterns. But in the last, you know, I mean, I guess 50 years, you know, we've sort of unlocked the ability to peek into the DNA, the genetic code and have, you know, a much greater amount of data and that's really sort of, you know, peaked in the last 10 years where now we can get whole genomes from things. So it's given us great power to sort of more, you know, more easily and more sort of confidently assess these evolutionary relationships, but also has become more challenging, you know, and that we have, you know, tons more data. And so getting that data but then analyzing it, you know, has sort of made it so that biologists now need to have backgrounds and genomics and bioinformatics and computing. And so, you know, when you watched me on my computer, it's often what I'm doing in my, you know, if I have little breaks here and there, but it's just remote, promoting into a computer server somewhere and running the next analysis for some new set of things because each analysis often takes takes a while to run. And so we just keep, keep plugging away.

Speaker 1: But I can only imagine, and I guess today I'm excited to sort of carry that theme forward because we're going to be talking about a bee that everybody's familiar with, but I have a feeling that as we peel back the layers of its evolutionary history, it gets stranger and weirder. We're talking about, well, there's the genus Osmia that everybody knows. There's Osmia Lignaria and in the East people working with Osmia cornifrons. And so I think most people are, you know, surprised to learn that there's more than one species of Osmia. Can you give us a broad overview of the bees and the genus Osmia? And in particular, this subgenus of Osmia that seems to be so important. Where are they located in the world? And tell us a little bit about the group.

Speaker 2: Yeah, I might start just a step back, you know, just to say, I mean, bees, of course, there's 20,000 species globally. And so those of us that work on sort of bee diversity generally always like to mention that point. Because a lot of people, you know, they sort of, you know, simplify, you know, or think, you know, just the thing of just the honeybee, or maybe now that at least Osmia is becoming better known, there's just the, you know, the one mason bee species. But the reality is there's, you know, thousands and thousands of species, you know, many more, most of which we don't know very much about. But, you know, so there's, you know, of that larger diversity, you know, they're separated into a number of families of bees. And so Osmia belonged to the family megacillity. And this is a group that includes one of the larger families, just 4,000, over 4,000 species. And a lot of things I'm saying, I'm going to say about Osmia, even the subgenus, you know, a lot of these things sort of apply to the whole family.

And there's some similar characteristics. But the, you know, the genus Osmia, you know, includes about 350 species globally. And it's more or less split evenly between North America and Europe and Asia. Although there's a few more species in the Eastern Hemisphere. But they're all sort of mostly, they're all solitary species. So they're not social like the honeybee. And one of the characteristics that's common is that they nest in sort of pre-made cavities. So a lot of solitary bees are ground nesting bees. But Osmia and most megacyled bees nest in these pre-made cavities, you know, in burrows either, you know, from the beetles have made in wood or stems or in crevices under rocks. Or one of the cooler and more interesting ones is there are as few species that nest in snail shells even where they, you know, they go in and close off the entrance. And their actual nest cells, and often the entrance, they cover with something either mud or chewed leaf material. And it's really that use of mud that they've gotten, you know, their common name, one of their common names, you know, are the mason bees.

So they're doing masonry to create their nest cavity. But, you know, there's this, you know, very large number of species in this group that have an amazing diversity of sort of life histories and different behaviors and sorts of things. So it's a cool group of bees to study. And so the subgenus Osmia, you know, is just one kind of subgroup within this larger genus, you know, that shares some of the, you know, some characteristics with the larger group, but you know, certainly has some of its own peculiarities. But so the subgenus, you know, it's quite a bit smaller. There's 29 species currently known are described and a number of sub species.

So those are sort of less, you know, sort of formal, you know, sort of, you know, sort of group, you know, sort of class of, you know, sort of below this sort of, you know, group of organism below the species that sort of just generally demarcates something that looks slightly different, but probably is of the same species. And within that diversity, there's definitely, it's definitely lopsided in terms of where they occur. So, you know, one thing I think is always really important for people to understand is the only species you're talking about, you know, generally doesn't occur everywhere, you know, there's a there's a native distribution. And then sometimes it occurs outside of that because it's been, you know, introduced there. And so this is one of the issues actually within this group, because they're useful in pollination and have been, you know, developed as managed pollinators, people have started sort of moving them around to see if they're useful in other areas. But so the sort of North America only has two native species of the osmia, osmia subgenus.

Speaker 1: So just two of the 29 are in North America. That's right. Wow. Okay. So they're really, really that lopsidedness. There's a whole lot of them in Europe and Asia. You only have a, okay, well, that's amazing. Yep.

Speaker 2: So, and actually, so that and this is an interesting pattern in North America in general, thinking of the whole genus osmia, most of the species are in Western North America. And so there's only, you know, you know, a few species, I think 27 or so in Eastern North America. And that pattern is sort of mimicked here where there's two species of osmia, osmia, they occur in Western, the tubult occur in Western North America. But only one of them, and it's just one of the subspecies of the species occurs in Eastern North America.

It tends to be less abundant there. So there's two in the West, one in the East, and then all the rest of the diversity is in what we call the Old World, which is, you know, Europe, Asia, Eurasia, the two

Speaker 1: species that we would find here in the West is osmial agnaria. What's the second species?

Speaker 2: That's osmia ribofluorus. So osmial agnaria is the, you know, blue orchard bee, and then ribofluoruses sometimes called the blueberry bee.

Speaker 1: That's right. I remember hearing Jim Cain speak about it being in some places really dependent on manzanitas and plants in there, Casey. Okay. All right. Exactly. Okay. So the other thing that I've often been told about this group is that they're very hard for taxonomists to identify and separate. Can you just walk us through why that is and how this has kind of been an obstacle to under, you know, maybe understanding these evolutionary relationships?

Speaker 2: Yeah. I mean, you know, the job of systematists or taxonomists, you know, is trying to figure out, you know, what the different species are and then how to tell them apart. And, you know, we do this by, you know, collecting samples in the field, putting a pin through them, you know, we call mounting them and then looking at them with a, you know, high magnification microscope. And the reality with any, with most insects, you know, is that they're quite small, you know, and, and I mean, bees tend to be, you know, larger than some, but the, you know, the, you know, the features we look at are all, you know, really tiny. And so it's, it's, it's, I guess for starters, it's often very difficult, you know, just using your eye in the field, you know, to be able to tell what the species are, you know, so especially when there are, you know, tens or hundreds of species, and they're all closely related. And so that usually means they tend to look more like, you know, finding those characters that differentiate them is challenging. And, you know, I'm, you know, this, this question of like, you know, Ozmium being harder than other groups, you know, I mean, that there is this, you know, just, you know, for a feature that some, some genera, you know, you know, tend to just be more challenging, you know, or the characters. And what that usually means is that the characters are, you know, less obvious, more subtle, maybe smaller, you know, or sometimes, you know, there's variation that's just hard to deal with, you know, where, you know, I think, you know, one problem that non, you know, that this just doesn't always come across to folks that aren't trained is that, you know, they think that a species is going to be very, you know, static, you know, that you look at individuals everywhere, and they're going to look the same.

But the reality is there's not, you know, nature is very messy. There's a lot of variation. And usually, you know, when you see that a species has a really wide distribution, very often across that distribution, you know, they look different, you know, so sometimes the character that maybe defines that species, maybe in some places it's really, really clear, you know, it's like there's a horn on the, you know, the face that's really distinct.

But then you look at, you know, another location or even individuals are in the same location, and sometimes it's less distinct. And so that's, I think, one of the issues with osmium is just the combination of, you know, the closely related species have very, you know, the characters that differentiate them are, you know, are challenging to see and to describe, you know, easily. But then those things tend to vary within species. And so it takes a lot of time of looking at a lot of specimens to really understand, you know, what those special characters are that differentiate them and then how, you know, how they vary, you know, within each species. And I think on top of that, you know, males and females, you know, differ morphologically. And sometimes it's easy to tell the females apart, but it's really hard to tell the males apart. Right.

Speaker 1: And you don't catch a family of them, you catch them one at a time. So.

Speaker 2: Yep, yep, exactly. So you're, it's rare to say, collect, you know, a mating pair together. And so usually you're sort of collecting in an area and you're lucky if you get both a male and a female at the same time. And then you still have to sort of, you know, make a guess, you know, there are these male and female, you know, specimens of the same species or not. And usually you're sort of doing that initially with morphology and making a guess. But what's kind of fun is now with molecular data, we can, we can often confirm, you know, that, that they're the same by sequencing the DNA and seeing that they match.

Speaker 1: Well, it does strike me just to pick up on that theme that you mentioned earlier that in some ways the B world, the native B world was one of the first adopters for molecular technologies. And I've always, you know, run into it in terms of barcoding. So it's barcoding this mitochondrial gene. Tell us about the techniques you use here and, you know, some of the limitations of using that barcoding.

Speaker 2: Yeah. So as I already sort of mentioned earlier, one of the breakthroughs in the last five, 10 years has been the ability to sequence, you know, not only a single gene, in the case of the barcode gene, it's one mitochondrial gene. But now we can sequence, you know, the whole genome or at least sort of what we call genome scale data, which is getting sort of, you know, a bunch of genes across the genome, but not necessarily the whole genome. And, and that's sort of the dominant method right now is the sort of, you know, getting mostly a big part of the genome, but not the whole genome. And the reason we sort of are, are say, not just doing the whole genome is it's all about, you know, the, you know, the costs involved. And so, you know, the more you sequence, the more it costs per specimen. And so if you can do, you know, get enough data for less money than doing a whole genome, then you can do many more individuals. And so this particular method that we use in this paper is one of these approaches where you are getting, you're able to get, you know, several thousand sort of genes, in this case, not the mitochondrial genome, but across the nuclear genome. And you can do that for much less money.

So you can sequence a specimen, you get these, you know, several thousand genes for about $30 to $40 a specimen versus for a genome, it's still the costs are around, you know, a couple thousand dollars per specimen.

Speaker 1: Wait a second. Let me get this straight. So this, you just, you just said, like, if you were going to sequence the whole thing, this one specimen, you'd be putting $3,000 down on the table, which would make many people cry. But you're saying that this technique where you're kind of like skipping through and picking little parts can be like $30. So way, way cheaper. Did I get that right? Exactly. That's correct. Let's be darned. Okay.

Speaker 2: I mean, you know, the things that, you know, we sort of keep, keep an eye on, you know, are these technologies and how they're changing because probably it will be five, 10 years and you can do whole genomes for $30, you know, and, and, and, you know, there are some ways to do that already, although the quality isn't quite as good. So, you know, things are just changing so fast that it'll be very soon that that's what, that's what we're doing.

Speaker 1: Well, I guess in contrast, we were talking about this real standard way that has been become standard practice. This might have conjured, that's a lot cheaper than $30.

Speaker 2: That's right. Yeah. So it's, I mean, it's actually not much cheaper, which is why our lab has been, you know, sort of doing this, you know, this kind of genome scale approach. But, but, but even, but people are starting to come up with new methods that they're making that barcode approach, you know, even cheaper. So probably, you know, just a few years ago, you know, doing the barcode gene would cost you $5 to $10 depending on how many samples you're trying to do all at once. But there are newer methods now, even using these handheld DNA sequencers, where you can potentially get that barcode gene for less than a dollar or a sample, using some sort of clever

Speaker 1: simplifications. I'm just going to stop there. Handheld. What do you mean, handheld, like, like a phone?

Speaker 2: Yeah. Really? Yeah, pretty much smaller than a phone even. I mean, you know, you definitely need some equipment and you need, you know, some technology in addition to the sequencer to make it all work pretty much with a few lab items, a laptop and the sequencer, you know, which, which really is, you know, it's, it's about the size of a cell phone. You can, you can generate this, this data now. So there's a company, Oxford, Nanapore Technologies that makes this device called the Minion, that is, is very, it's very quickly sort of being developed and improved so that you can, you know, generate sequence data, you know, in your, at your house or, you know, in a very small lab for less money, including, you know, from barcode genes to whole genomes. And that's a technology that's, you know, has a potential to really revolutionize, you know, sort of quick and cheap, you know, sequencing and identification of species.

Speaker 1: Okay. So let me recap this. We've got a group of Bs that's been traditionally, you know, just by luck and circumstance, they're just hard to tell apart. So there's a kind of ambiguity into sort of how they're related because you can't even, maybe in some cases, resolve some of the species apart. It looks so similar. And so along comes this technology and now it's getting cheaper and cheaper. And so finally, a point in history has arrived where you can actually kind of separate these species up like you couldn't before.

Speaker 2: Yeah. One of the things I guess I was going to comment on, I mean, so the barcoding approach, I mean, it's one gene, it's been, you know, because it's cheap and, you know, it sort of was adopted as sort of potential, you know, one marker that could potentially separate and identify species for not a lot of money. And it's fast evolving. You know, so there's, so for even, I mean, so like, you know, genes evolve at different rates and, you know, closely related species, you know, tend to have, you know, not have diverged that long ago. And so you need something that evolves faster so that it can actually differentiate, you know, very recent, you know, events in evolutionary time. So the barcogene has sort of generally been a pretty good marker for animals to separate species. But actually because it's a single gene and it's fast evolving, it's pretty good at, you know, species differentiation, but it doesn't work as well at sort of, you know, confidently, you know, resolving, you know, deeper splits. You know, so you might be able to say, well, these two closely related species, you know, this barcode gene says, yeah, they are closely related, but you go back a little farther in time, you know, and have more disingling related species. And then that one gene sort of doesn't work as well, where there's just, you know, you have one nucleotide, you know, within the gene that sort of multiple times, you know, has, has evolved, you know, the same base pair.

And so you start getting this noise that, that, that just confounds whatever signal there is to reconstruct it. And that's where having more, more genetic data, you know, can be really helpful.

Speaker 1: And so they might be going at different rates, I meant, I'm picturing a deck of cards that when you're, you have two decks of cards and you've been shuffling them, but if you had, if they were all being shuffled at the same rate, it gets too, you can't tell these different branches apart. But if you had some of that were slow and some that were fast or something, you could start to get into these deeper histories. Yep, exactly.

Speaker 2: Yeah. So, so that's what's really great about these, you know, these approaches that give you this genome scale data, that you can have, you know, some of those genes will be slow and they're going to resolve those really ancient, you know, divergences, you know, with a lot of confidence. And then you'll have these fast ones that are better at these very recent ones. And so this approach that we use, what's great about it is it gives you sort of resolution at all these different scales, you know, from millions, you know, from tens to even hundreds of millions of years ago, to very recent in time from, you know, potentially even, you know, tens of thousands of years ago. And so it doesn't know simultaneously, whereas the barcogene has a little bit more restricted use.

And there's more and more evidence, you know, even saying that even at that really shallow scale, where the barcogene has generally been really good, there are some cases there where even it doesn't perform well, but these larger data sets, you know, these methods that give you more data actually do. And so it costs a little bit more, but you actually get more from it. And so that's why, you know, I tended to use that approach.

However, because of, you know, the fact that you can maybe start doing barcodes for less than a dollar, you know, and it works in a lot of cases, at least for identifying species or differentiating them, it still is a popular method to use.

Speaker 1: Okay, I think that sets us up really well. And that is the best explanation of this field that I've ever had. And I'm hopeful listeners have appreciated that we've kind of like dove quite deep in, but at least it sets it up and allows us to discuss your research.

Let's take a quick break and let's come back. And I want to get into into the mystery of the subgenus Osmia and its evolutionary history. And so we've got, got the techniques down there, these really wonderful techniques for resolving and different species out. And you also mentioned kind of like diving back into history and being you tell us a little bit about some of the relationships between the species and the subgenus Osmia that you found and what were some of the kind of like broad themes that came out in your analysis?

Speaker 2: Yeah, I mean, one of the things, you know, so this isn't the first study to sort of look at phylogenetic relationships, but it's the most comprehensive in terms of the number of species that have been included.

And in terms of course, the just the number of genetic loci. But from the previous study, you know, there were there are a few relationships that were really interesting, but weren't super well supported by the data. And we really wanted to try to resolve, resolve those things. I wanted to start by just commenting on, you know, to me, what you two, one of the most important things was, was resolving, you know, the position in the phylogeny of the two North American species, you know, Lignaria and Ribofluorus.

And the reason is, I mean, partly just this interesting question, right? Like, you know, are these two species that geographically co-occur, you know, are they, you know, closely related to one another, or are they not?

Speaker 1: They're not. It would stand to reason that they might be, but exactly.

Speaker 2: Yeah, exactly. I mean, you might, you know, the morphology, you know, had, you know, certainly suggested that they were, they were quite, you know, they're quite different, but you never know, you know, things can really come, you know, surprise you. But you know, often, you know, I mean, you know, one, you know, null hypothesis is, you know, that things sort out, you know, geographically. And so that was one of the things we kind of wanted to test. And so the previous study had sort of found this pattern that they, that the two North American species, you know, weren't closely related, you know, within the group.

And then actually this, but the, the, the species that is sort of the, the sister or the outlier, you know, you know, you know, separate from all the others was one of the North American species, the blueberry bee, osmium ribofluorus. But that result hadn't been, you know, very strongly supported. And so in our analysis with this bigger dataset, we actually confirmed that result with, with really high support. You know, so analyzing the data a lot of different ways, we always get that, that relationships. And this blueberry bee, osmium ribofluorus, which is sort of an outlier from all the other species is, you know, sort of the, what we call the sister group, you know, sort of, you know, to all the rest of the species. And that just means that all the rest of the species are more closely related to another than to, than to osmium ribofluorus. But we found sort of broadly that there are these four groups, you know, that, and again, this was sort of, you know, suggested in the other study and we sort of are confirming it. But it's, you know, we're always, you know, systematists, you know, we're trying to, to classify diversity and make it easier to, you know, sort of communicate about it. And, you know, to talk about, you know, so you can communicate, you know, these relationship, you know, sorts of things that we find. And so, you know, you often get these phylogenies, you know, you see how things are related. And then you try to look for some morphological, you know, or some kind of correlates, you know, that, that makes sense. And so with this phylogeny, we've been able to find these four groups, you know, that we sort of have named by one of the species in that group. And so there's the ribofluorus group, which is right now just one species, but potentially more. There's the apocata group, which is sort of a Mediterranean group of four species. The emergenata group, which is slightly larger and sort of includes sort of things in the Mediterranean region and Europe. And then there's this much, the largest group, which is called the bicornis group or clade, that includes actually all of the agriculturally important species. And each of these groups, I mean, with the exception of ribofluorus, you know, has some morphological characters that can sort of that have been sort of found you, is really the combination of whether it has these horns on the head or the sort of clippies, which is kind of like the upper lip.

And then also the, the length of the mouth part, whether they're, they're long or short. And so depending on the combination, there's two things you can, you can sort the species into these, these groups. So the bicornis clade, you know, one of the, you know, it's like, like bicornis is like two, two, two horns, essentially.

And, you know, one of the characteristics of this group, you know, is that a lot of the species, you know, most of them have, have these protruding horns on the clippies, which can be a very sort of striking feature. And so it's in that group, like I said, where we, all of the agriculturally important species belong. And it's where the osmeolignaria, the blue orchard bee belong. So what's kind of cool within that group is that the blue orchard bee, you know, the other one, the other species that's North American is sister to all the other ones, which of course occur in Europe and Asia.

And so you sort of see this repeated pattern. So lignaria and ribofluorus are not close relatives. So they're separated. And then you, but you have them sort of being both being sort of the sister species to, you know, these larger, you know, sort of, you know, important groups. But what it suggests, you know, even without sort of a more rigorous analysis that we did do in this paper, but it sort of immediately suggests that, you know, that there's been movement between the continents, you know, and sort of a more complicated evolutionary history, you know, over, over time, you know, with things moving around, specinating, and moving back.

Speaker 1: Well, I was, I was thinking, how is it possible to have, you know, we have these two species in North America, and they are kind of on opposite ends of the family tree. I guess it would suggest that there was, you know, whoever came over here to begin with, there was, you know, there was a more diversity, or there's, there's a lot of, you know, species that no longer exist.

Is that what it means? That, you know, and lignaria is the lineage of that one? And yeah, is there any other explanation for why, how you could have only two species here, and then being on really opposite ends of the tree?

Speaker 2: Yeah, well, it's hard to say. I mean, you know, we often do kind of asymmetric, you know, topologies, you know, where they have these two sister groups, and one has a lot of species, and one has few. I mean, it's a pattern you see all over, you know, the tree of life. It's one that's sort of really intrigued, you know, systematists and biologists for a long time and trying to explain those disparities.

And I think, you know, the reality is that it's, you know, there's no one explanation, you know, that the history, you know, can be, you know, random and stochastic. And so, you know, it could just be, you know, kind of a combination of, you know, maybe there were more and more species in North America, and then they, whatever reason happened to go extinct. Or it's just for whatever reason, they haven't differentiated, you know, they haven't, whatever allowed them to become more diverse in another, in the other region, in this case, in Europe and Asia, just those conditions didn't exist here. And so, I mean, you know, what we see in the group overall, kind of the deeper level, is it seems like, you know, the, you know, the Palearctic, or the, you know, Europe and Asia, you know, has been sort of a center of diversity for, for osmium bees. And so, it just seems like it's an area where they've been around longer, so time might be an explanation. And for whatever reason, they've done well at diversifying there.

And, but they've, you know, occasionally crossed over into North America, and at least in this case, they just have never, they've never, you know, they've, they've clearly kept a presence, but they haven't really diversified, you know, the, you know, either because of extinction or just lack of, you know, speciation.

Speaker 1: Okay, yeah, go ahead. I've got another question after that.

Speaker 2: Yeah, this is kind of a random, you know, thought that I actually just, just popped in my brain right now. But, you know, so these, you know, this group, right, is, you know, they've become, you know, managed pollinate pollinators of orchard crops, you know, including in apple orchards. And, you know, similarly, you know, like just thinking about the apple, you know, it's thought actually it originated, you know, in I think Kazakhstan

Speaker 1: region, so the Paleo Arctic, yeah, parallel thing even where, you know, there's maybe, you know, several groups and even, you know, these, these, you know, plants and the bees in case that are interacting, you know, maybe have similar patterns of originating in the Paleo Arctic, you know, coming into the, you know, New Arctic, but, you know, because they're sort of newer arrivals, you know, maybe not, you know, not diversifying as much. And maybe Lignaria remembers its tree fruit roots. That's right, yeah. Well, I guess the other thing is I'm looking at these, you know, there's a really nice figure where the family tree is laid out and it almost looks, and the way that you describe it is ribofluorous, this blueberry bee is really, you know, kind of the only, seemingly only kind of descendant. I think this is what you were saying earlier, that when you look at this by cornus group, there's just a lot of diversity, but this one little arm that seems to be the orphan arm of the subgenus osmy only has one species that I guess that's maybe what you were saying that in Europe, either time or conditions or whatever has led to radiation, but it's not like the ribofluorous arm radiated in the Americas, even though it seems like it's been here that long.

Speaker 2: Yeah, yep, that's exactly right. And it's just, it's hard to know why. It does seem like, you know, we have, I mean, it's clearly not, you know, at least morphologically, there's clearly not as differentiated as much. There is some evidence that there may be more than one species, you know, maybe as many as three or four, and we're sort of actually working on that as from a new project. But even with that sort of, you know, potential added diversity, it still isn't, you know, it's not, you know, it's still quite asymmetric in terms of, you know, one group and the other, it's just hard to know, you know, I mean, I, you know, within, you know, over the last 12 million years that, you know, this group has seemingly existed, you know, climates and habitats have changed a lot. And for whatever reason, they've just, they've done better evolutionarily in the old world.

Speaker 1: I imagine that is one of the things that you always are guarding yourself against. There's the just so story of evolution where, you know, you can explain things retrospectively, but not really because there's so much missing, and you really only have these fragments of the past that you just analyze their DNA. Yep.

Speaker 2: Yep. Exactly. Sometimes there's very clear correlations, you know, where some group in some area just radiates, and then you can, you can say, you know, in this group, you know, it evolved this trait, you know, maybe now it's, it's pollinating this flower or it's nesting in this habitat or in this type of, you know, micro, you know, kind of habitat.

And it's clear that that, you know, that is what maybe has allowed it to be more successful. But in a lot of cases, you know, we just don't know, and it could just be just, you know, I mean, there's always a part of it is always randomness.

Speaker 1: Well, I guess one question I have, I was reading in the paper that one of, we had Kate McCroy on just a bunch of episodes ago telling us about Osmea torus is a, you know, potentially, you know, very good, it really likes to be in Maryland, seems to be doing very well out there, and the species that we really keeping our eye on as an exotic. And the one thing I noticed was, first of all, I guess, one thing that's concerning is that, you know, that one group where Lignaria is has a whole lot of, there's a whole lot of diversity, but it's not in North America.

So the potential for competition between related groups, maybe is, you know, quite a concern. But I suppose the other thing is I remember reading that the Osmea torus was also, there was a lot of variation within it. So you were talking about this earlier, how you have a species and it has a large range and it can look quite variable. I wanted to hear you speak just about some of these exotic Osmea. I know the Logan B lab has been really working on developing tools for identifying these, but also just maybe specifically with Osmea torus and its sort of variability and appearance.

Speaker 2: Yeah. I mean, just the whole issue of non native species, you know, coming in, getting established, and then potentially competing with native species, you know, is just an issue of major concern. And some ways it's been less of an issue, maybe in bees, just because we don't have a lot of evidence of there being major problems, you know, of either, you know, killing a tree species or becoming a pest in certain crops. I mean, bees are generally pollinators. And so it's interesting about this group in particular, is because they've become, you know, I mean, so it's really important about them, you know, agriculturally, is, you know, there are these number of species that have become developed as managed pollinators, you know, sort of a solitary bee managed pollinator that can be used as an alternative or in, you know, conjunction with the honey bee, which is a social species. And so our, you know, USDA lab has really been, you know, kind of one of the, you know, the first labs to develop, you know, these solitary bees for pollination purposes.

And so Osmeil, Lignaria has become one of the major ones. And, you know, our lab has studied them for a while. But there's, you know, a number of species within this group, you know, in Asia and Europe, and in the US, the people who have identified, you know, have attributes that make them, you know, maybe easier to be used and manage pollination. As a consequence of that, you know, initially, before people were as concerned about non-native species, you know, they said, oh, well, this one's going to be working really well, you know, in Spain, you know, Osmeil, you know, Cornuta, you know, cornifrons, let's bring it over into the US and, you know, see if we can use these same methods and have it pollinate here. And so actually, some of the species in this group were intentionally introduced.

So Osmeil cornifrons, which is actually native to Asia, was intentionally introduced into the US, you know, for pollination to see if it could be used to improve, you know, agricultural output. And so at the time, that seemed fine. But now as we're, you know, looking closer, sometimes, at interactions, we see that it's not always necessarily good. And so certainly with things like bumblebees, people are more and more concerned about, you know, pests and pathogens coming in with these other species, and then those may be getting out into other native species, and that potentially having negative effects. So in general, you know, we don't, you know, I mean, I think, you know, documenting those potential negative effects is still sort of ongoing. And, you know, there hasn't been a lot of real clear examples.

And so, you know, I feel like it's not, you know, the non-native, the non-native bee issue has not been as great of an issue as it has been, you know, in some other groups. But there's this one case of Osmeotaurus. So it's a torus was thought to be accidentally introduced, potentially with cornifrons. And so both of those species are now established in the east.

And I think cornifrons maybe also is found in the west now. But so there's new research kind of finding that there is some competition between these introduced species and the native species. And so I know, you know, Kate LaCroix has been working on sort of the effects, potentially a torus, on native Osmeos species in the east and finding some, you know, some negative interactions. And one of the ones that have been sort of thought of people have been commenting on it for a while is so Osmeolignaria, you know, there's two subspecies, one in the west, one in the east. And people have been kind of noticing a decline in sort of abundance of the eastern one. And so it's been people have wondered if maybe that's because of these introduced species.

And I think there's some evidence now that could be the case with Osmeotaurus. And so there's a lot of, you just, I mean, so there's, you know, I guess one people are really just to see, you know, is there competition, you know, is there some negative effect of these introduced species. And of course, you want to, if we know what all the species are, we want to keep an eye, you know, out to look for them.

Because if they are introduced, you know, it's better to, you know, I mean, we want to try to avoid these kind of accidental introductions in case there are unintended consequences. Now, in terms of my research, you know, we were, I mean, it's probably one of the reasons we wanted to, you know, generate this molecular phylogeny, resolve these relationships, better understand the systematics is because they're these species are being introduced, is we want to know as much as we can about them. And so in addition to making this this kind of well resolved, you know, species level of phylogeny, we also pulled out this barcoding gene from our data, kind of a neat trick that you can do.

And then we combined it with this data and this larger database of barcode sequences. We just asked the question, you know, are you know, are all these, you know, these things, these, you know, sequences that we're calling this species, you know, are they all clustering together or not? And one of the things we found with Taurus is that they're actually the sequences sort of form a group of that include three named species, Osmia rufina, obvious, Osmia Taurus, and Osmia rufinoides that potentially suggests that they're, they're all one species.

And this is sort of ongoing research that we want to get more samples on. But, but actually, if they were all one species, the oldest name in the group is Osmia rufina. And so if we were to, you know, do this culture synonymize the names and the one name, Osmia Taurus would become Osmia rufina.

It would mean that this thing that people have been studying, you know, Taurus as this introduced species in the US actually would not be called Taurus anymore. So that's where there's so communication. Oh, sorry, go ahead.

Speaker 1: No, no, so just to repeat that. So really, people have been identifying that have these three have kind of characterized these three species. But when you go through and do the genetic work, I was looking at the figure here, they may have diverged only a million years ago. So they're, you know, very close. And so there may be justification for reclassifying them to the most ancestral arm, which would be rufina. And, okay, did I get that all right? Mostly.

Speaker 2: Yeah, I mean, the, just, I guess, one comment would be, you know, in terms of which name would be, you know, what sort of subsumed them all, you know, texanomus use what's called the principle of a priority, which is part of the, you know, the international code of zoological moment plagiarism. It's not, it's actually not a result based on the phylogeny here. It's all based on the fact that that name was described first in the literature.

And so, yeah, all of the names that are available to be used, you know, if you're going to merge them all into one species, you pick the oldest available name.

Speaker 1: Makes sense. Because the person who came up with rufina, they were actually right. So we will reward them with the name. Okay, cool. Yeah.

Speaker 2: But I just, I'll say this is all, you know, somewhat preliminary because, you know, the mitochondrial data that we have is suggesting this. But it's, you know, there have been cases where clearly this mitochondrial gene just doesn't do a good job separating species.

And so one of the things we're trying to do now is sequence a few more individuals with this genome scale data, and to get a little bit broader sampling of individuals, both in the introduced range and in the native range, and see if we can, you know, can resolve this confidently.

Speaker 1: Well, that's really interesting. So the, in addition to being able to resolve the history of this fascinating group of bees, I guess by knowing, you know, some of this information can then be used to sort of perhaps suggest, well, these three groups, you know, this, this, this species, there's some evidence of it being, you know, doing very, very well in a new location, maybe these other, other groups, we should keep an eye on them because they're closely related. I suppose it has, it'll, it gives us some predictive power, although you never really know until, I suppose those are some of the, or I guess for economically important species, they may kind of be real closely related.

There might be something about that evolutionary history that predisposes them to being managed or something. Yeah. I mean, that was a bit of a stretch, I suppose, would you say that?

Speaker 2: Well, just as you're making these phylogenies, you know, it's like, what's the point? And I mean, it's, it's a structure for, you know, for, for, it's a sort of predictive framework really, you know, I mean, the general, you know, hypothesis is that if two things are closely related, you expect them to share, you know, more features with one another than something else that's more distantly related. I mean, you know, like I said, I mean, nature is messy and, and things can surprise you.

But, but in general, you know, that's, that sort of pattern holds true. And so yeah, if you had one species that was really great at management, you know, but for whatever reason, it's in decline or it's gone extinct, you know, man, like we don't have our pollinator anymore, what species might we look at, you know, to replace it? You know, yeah, good, a really good, you know, strategy would probably be to look at the phylogeny and pick, you know, look at the species that are closely related and study their biology, you know, and see if they have the same attributes that made, you know, the other species good at pollinating. And, and that's why I mean, really, you know, we see that in this plate already, you know, within the bicornus clade, there's at least five species that people have developed for managed pollination.

And they do differ, you know, from species to species, but at the same time, you know, they're, they're showing themselves to be, you know, you know, good at, good at this, you know, good in these managed settings.

Speaker 1: Well, this was great, fascinating. I am, I really, it's expanded my appreciation of this, of this group. Well, so we really appreciate you taking the time. But we will hold on just a second. We have one last segment. We'd like to ask you a couple of questions that are unrelated to all of this book recommendation and go to tool. So we'll just grab, let's take a quick break and we'll come right back. Okay, we're back. So do you have a book recommendation for our listeners?

Speaker 2: Yeah, I recommend partly because I'm reading through it myself right now in more detail, but there's a wonderful book called the solitary bees biology evolution and conservation edited, or sorry, not edited, but sort of written by Brian Danforth, Robert Minkley and John Neff. And maybe others have already recommended this book, but it's just, you know, it's just a fantastic book, you know, focusing on the non social species of bees and why they're important as pollinators. But but also just about all the quirky cool things that bees do biologically. And it's really up to date with the latest literature. It's a great, great resource.

Speaker 1: It's a really great book. And we do have an episode with Dr. Danforth when talking about the book when it came out. But the one thing I was going to say is John Neff is going to be our speaker at the Oregon B Atlas conference. I'm really looking forward to hearing him talk about all the work that he does in Texas. Awesome. Okay, so that's a great book suggestion. You're doing good. Let's see how you do on the next one. Do you have a go to tool for the kind of work you do? And just I can't imagine what that's going to be.

Speaker 2: Yeah, the go to tool. Well, I would have to say the Illumina high seek DNA sequencer is the go to tool these days for generating these, you know, these, you know, genome scale data sets.

Speaker 1: Is it the size of an oven or a shoebox or what does this look like?

Speaker 2: Yeah, I would say an oven is a good, probably a good, yeah, very similar shape and size for sure.

Speaker 1: And I guess you you we were talking about this at the break, you you often you go into the collection and you'll take a B leg off and you'll take the DNA off and what it what goes into the oven?

Speaker 2: What's the yeah, I'll say I mean, you know, it would be a sad world. I mean, most of what we work with is these little vials of little clear, you know, clear liquid, you know, we just pipe that them back and forth between, you know, to you know, little snap cap tubes, you know, adding, you know, little ingredients here and there, you know, kind of like a witch does. And in the end, you know, you get this purified DNA that's often you just, you know, 10 microliters, you know, extremely small amount of liquid of material that goes in the oven, you know, and now you get, you know, these gigabases of DNA sequence data. And so most of my world is often, you know, is that. But but it does start, thankfully, you know, with the specimen that we've collected in the field and put in the collection. And by making that, sometimes, yeah, just lose that link sometimes between the specimen and the molecular world.

Speaker 1: Although it must be, you know, this is the place North America to do this work with such such a great collection located in Logan has been well curated and must be make your job a lot easier to be able to open up a drawer and know you have authoritative determinations on specimens and you can work from there. Definitely.

Speaker 2: And this is a fantastic place to be. And I mentioned this to you earlier before the beginning of the process, but my background is in is an aunt. And so I'm still learning a lot about diversity and taxonomy. But you know, we have this collection with over 1.5 million specimens that several people, but most recently, Terry Griswald is really built up to what it is. And you know, we've, you know, both collected a lot ourselves, but also, you know, acquired, you know, material from others. And we still would like to acquire more to really be, you know, an epicenter for for for be systematic research. And reality is me for identifying things. And even with a good key, a morphological key, it's still often hard to use those without a reference collection, a specimen to look at. And so, you know, it's one of the things that's really wonderful here, especially for the Western US, you know, we probably have, you know, the best collection of identified bees of anywhere.

Speaker 1: Well, being that the case, that brings us to our last question of all those little bees. Is there anyone that sort of particularly you have a fondness for? And that's a lot of them.

Speaker 2: Yeah, such a tough question to answer. You know, I definitely don't want to say Osmia, because that's what we're just talking about for an hour. But, you know, honestly, I'm a sort of tropical biologist at heart. And so I love, you know, all the diversity, you know, and the species in the temperate zone. I love going to the tropics and seeing stingless bees.

So people know these are social bees, but they don't sting, as their name suggests. But they're really cool, because they're very diverse in the, in the, you know, South America and Central America, as well as in Southeast Asia and Africa. And there's a bunch of species, they all have really cool biologies, and they make honey. One of the things I learned recently is, you know, there's people that work in both, you know, South Australia and in South America, that, you know, study the different honey making species, and they even try to, you know, cultivate them to make the different kinds of honey and to use them in pollination, and sort of for tropical fruits. And it's just a fascinating sort of group of bees and an area of research. And I sort of am jealous sometimes of the people that get to live and work on these bees.

Speaker 1: You know, I completely agree. I did see someone I was in Mexico, but we have an episode with Dr. Mike Bergett, and he, unfortunately with the pandemic, he was, he goes to Thailand every winter, and he studies stingless bees and apis species, and he is moping here in Corvallis until travel restrictions are lifted. Well, thank you so much for being so generous with your time. This is a great, I'm glad to finally have some of these techniques clear my mind, but I'm also fascinated to hear about this, this really rich history in the subgenus Osmia.

Speaker 2: You're welcome. It's great to be here. I appreciate having the opportunity to talk to you about our research and happy to come back anytime.

Speaker 1: Thank you so much for listening. The show is produced by Quinn Sinanil, who's a student here at OSU in the New Media Communications Program, and the show wouldn't even be possible without the support of the Oregon legislature, the Foundation for Food and Agricultural Research and Western SARE. Show notes with links mentioned on each episode are available on the website, which is at pollinationpodcast.oregonstate.edu.

I also love hearing from you and there are several ways to connect with me. The first one is you can visit the website and leave an episode-specific comment. You can suggest a future guest or topic or ask a question that could be featured in a future episode, but you can do the same things on Twitter, Instagram, or Facebook by visiting the Oregon Bee Project. Thanks so much for listening and see you next week.

Mason bees in the subgenus Osmia emerged sometime before the ice-age, likely in Europe and Asia, but they radiated into North America early on in their history, resulting in one of the most beloved solitary bees, the blue orchard bee. In this episode, we dive into the evolutionary history of this subgenus.

Michael Branstetter is a Research Entomologist with the USDA, ARS, Pollinating Insects Research Unit in Logan, UT. He specializes in the molecular systematics and taxonomy of bees. Using molecular data, his lab strives to understand the diversity and evolution of bees both within the U.S.A. and globally, and to use that information to improve bee conservation and management, especially in agricultural settings. He also tries to develop new methods and databases that reduce the taxonomic impediment and make it easier for non-specialists to identify bees.

Links Mentioned:

USDA Pollinating Insect-Biology, Management, Systematics Research Lab (Logan, UT)

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