Research Matters

Casey Dillman on the planet's most overlooked creatures - Research Matters S2E7

• Cornell University • Season 2 • Episode 7

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0:00 | 21:35

In this episode of Research Matters, we talk with Casey Dillman, curator of fishes, amphibians and reptiles at the Cornell University Museum of Vertebrates, about how studying some of the planet’s most overlooked creatures can reveal the health of entire ecosystems. It’s a conversation about interconnectedness, conservation and an unlikely key to protecting the future of the planet. Watch here.

Casey Dillman:

Fishes — there are more than about 37,000 described species of fishes on the planet. We're describing about one a day every year and have been for decades. So that number is continuing to increase. When you add up all of the other vertebrate groups, the amphibians, the reptiles, the birds and the mammals, those all together don't sum to 37,000. So the fish diversity in invertebrates —

Laura Reiley:

Fish win.

Casey Dillman:

Absolutely, hands down.

Laura Reiley:

I'm Laura Reiley, and today we're diving into the world of fish, frogs and reptiles, because sometimes the creatures slithering under logs or swimming beneath the surface are the best indicators of how healthy our planet is. Our guest today is Dr. Casey Dillman, curator of fishes, amphibians and reptiles at the Cornell Museum of Vertebrates. He studies biodiversity, conservation, and the incredible, and sometimes overlooked, ways these animals can tell us what's happening in our ecosystems. We'll talk about what happens when amphibians vanish, why studying reptiles actually helps humans, and what a jar of preserved fish can tell us about climate change. Welcome.

Casey Dillman:

Thank you.

Laura Reiley:

It's great to meet you. Yeah.

Casey Dillman:

You too.

Laura Reiley:

So I did a little bit a little bit of homework, and, it says that, in your collection, which is at the Lab of Ornithology for all of you, you have between 1.25 and 1.3 million individual fishes in jars.

Casey Dillman:

That's correct. We did the math recently. Everything's digitized.

Laura Reiley:

So there's someone counted all of these.

Casey Dillman:

We have cataloged everything, it's searchable, and there's over 1.3 million individual fish in the collection.

Laura Reiley:

That is tremendous.

Casey Dillman:

And about 1.5 million total specimens across all four vertebrate collections.

Laura Reiley:

Wow. So, I've heard you say that that these are that there's kind of, like, a time machine element of this. How do you describe what you get from all of these jars of fish specimens?

Casey Dillman:

That's a great question. It really depends on the question you're asking. Historically, specimens were collected for, like, biodiversity studies like describing new species, trying to understand the planet, what lives where, and where it's distributed, how things are related. We're still doing a lot of that in fishes. There's about one species described every day, every year, more than like 350 species annually are described and have been for decades now. But we also are starting to use the collection with new technologies in different ways, because the organism comes from the environment, and so is a record of the environment that it came from. And we can look at what it was eating by doing dissections. We can also use mass specs or GC machines to look at stable isotopes so we can see what something was, where it was in the food chain.

Laura Reiley:

Can you say what, what is the mass spec? Just for lay audience.

Casey Dillman:

So there's, it's a it's an instrument where you, basically, turn a piece of tissue into a gas and you run it through a machine, and it can tell you the carbon and the nitrogen and the different elements that are in there. And that gives you a bit of information about what it was doing in the environment when it was collected, where it was in the food chain. Yeah. And how it was getting nutrients moving up the food chain.

Laura Reiley:

So I'm assuming that was one of the new technologies you were just talking about. What are some of the other new technologies that you're bringing to bear on this collection?

Casey Dillman:

We do a lot of CT scanning with with my group right now. Like we're we're actually taking all these fish from the collection, and we are scanning them in three dimensions to make them sort of models of what they look like inside. And it's really fun because in the specimens themselves are very captivating. But sometimes we work with these really small.

Laura Reiley:

All right. You're going to have to convince us. Okay, captivating... I am I'm imagining, like a piece of fish in a jar.

Casey Dillman:

It's a whole fish. The whole fish.

Laura Reiley:

Oh, it's the whole fish.

Casey Dillman:

The whole fish.

Laura Reiley:

All of these. Okay.

Casey Dillman:

Yeah. So 1.3 million whole fish. Well, we do occasionally take tissues from specimens. Now, for genomic analysis, for sequencing DNA. But the organism itself has this sort of charisma. They're not megafauna and charismatic in that way, but they they tell a story and they tell us what they are, and we can now take these specimens and use X-rays and we can build a 3D model of it, so we no longer have to skin it and peel it and put it in a beetle colony to get the skeleton. We can leave the animal intact and see the entirety of the skeleton digitally. We can color the bones, by what they are. And then we can create these captivating 3D models, either on the screen or that you can print out so that people can see them. And so when you work with somebody that's really small, being able to blow it up into huge sizes, so you can look at it in detail is really... is really fun. And it's really a lot of things we're doing right now.

Laura Reiley:

So is CT scanning for this kind of work, a new area for you?

Casey Dillman:

It for me it is. Yeah. Like I came from a background of molecular work. Like if we would sequence DNA and try and build trees to understand, family tree relationships of species. When I came here nine years ago, I, I really wanted to make use of this amazing collection. It's the 10th biggest collection of fishes in North America. It's massive.

Laura Reiley:

All right, I think I saw, University of Washington has, like, a walloper of a collection.

Casey Dillman:

They have a huge collection.

Laura Reiley:

Is that because they're coastal and so they kind of we can't we can't beat them because...

Casey Dillman:

Yeah. Yeah.

Laura Reiley:

So also New Mexico, interestingly...

Casey Dillman:

New Mexico, yeah.

Laura Reiley:

They had a really huge like 5 million...

Casey Dillman:

Something like that. Yeah, it's massive.

Laura Reiley:

So the the things I've learned and prepped for this. So so tell us a little bit... So obviously you said you've been here nine years and I think were you at the Smithsonian just prior to that. What kinds of things were you doing there and what are you doing here that's a little bit different?

Casey Dillman:

So there I was, a postdoc. So I finished my PhD and I was continuing on the research track while looking for a job. And in that project, I was working on a group of South American fishes that are called anostomoids which includes four different lineages, and the, the people I was working with, Rich Vari was his name. He, over the course of 20 years, had looked at all these different groups and had described the anatomy in detail so that he could code all of the, um, pieces of anatomy as ones or zeros to make this what we call a biomatrix, so he could analyze it and he'd done that for each group at a time.

Laura Reiley:

What was his goal? What what was he trying to understand?

Casey Dillman:

To understand the history of the of the group, to understand the evolutionary history of those lineages. So my job in that place was pulling all of that together into one giant matrix, and then filling out that matrix for 280 species, for like 500 characters. And so I spent two years under a microscope, basically just observing it.

Laura Reiley:

This does not sound fun, like Night at the Museum or something like...

Casey Dillman:

It was fun. But it was a lot of work.

Laura Reiley:

All right. So a lot of your work focuses on biodiversity, and it's, you know, it's a it's a word we hear a lot. It's it's contentious, you know, obviously in some circles. For someone who's not a scientist, how would you explain why biodiversity matters?

Casey Dillman:

It's a great question. I think species and lineages that exist in nature have inherent value just because they've come into being. They have this long trajectory...

Laura Reiley:

That's very spiritual and, and and philosophical.

Casey Dillman:

And so they have that inherent value. And the way I look at is, it's, it's my job. And people like me's job to, to try and understand that history. And by describing species or understanding how they're related, we put the context of not only that species or things that they might be closely related to, or things that might be distributed in the same places. We put them in the context of the history of not only that group, but of the history of the Earth and how things have moved around. And so it sort of just informs us about the, the world that we live in, in a way that I find incredibly rewarding and meaningful.

Laura Reiley:

So do we have a sense of, of how many species there are? I mean, even just in the the herps, that's like... herpetology is...

Casey Dillman:

Amphibians and reptiles. You know, I think in herps it's probably better known... I'm the curator of the fishes, amphibians, and reptiles. My background is almost exclusively in fishes, though I have done a couple of projects in, in snakes. In terms of vertebrate diversity, it's... I'm sort of sidestepping your question to come at it from another angle. Fishes — there are more than about 37,000 described species of fishes on the planet. And as I mentioned a little earlier, we're describing about one a day every year and have been for decades. So that number is continuing to increase. When you add up all of the other vertebrate groups, the amphibians, the reptiles, the birds and the mammals, those all together don't sum to 37,000. So the fish diversity in invertebrates...

Laura Reiley:

Fish win.

Casey Dillman:

Fish win, absolutely.

Laura Reiley:

Well, so I mean, if we, what do we learn by really determining a total number and, and how does that inform how we treat wetlands and, and, you know, water management and conservation and those kinds of things.

Casey Dillman:

A lot of times, when you can have an isolated area: a pool, a pond, whatever, you can sometimes have something that's unique there. And so when you have those, it gives you a reason to sort of think this is a very special area and we should conserve it. We should think about this in the scheme of all of this, because it's like the Devil's Hole pupfish. It will never come back to existence, right, in the southwest, but it's in dwindling numbers. So it just sort of gives us a, a, a window into how these things come into being. And so, you know, we'll never be able to stop, development of places or anything completely. But by understanding where things are, we can get a sense of, of how to think about those regions as unique in the global history of, of evolution.

Laura Reiley:

So are there, I mean, I think we think of, extinctions and losses as kind of a one-way street. Are there are there success stories in your kind of research or experiments? Or even just in kind of what you've seen at, at the museum? And I actually was reading this morning that... I've done a lot of work on the Apalachicola Bay and oystering in Apalachicola Bay, and they just reopened or are in the process of reopening it for wild oystering.

Casey Dillman:

Okay.

Laura Reiley:

Which signals that may be water, water conditions and that oysters are kind of coming back. So where are the where are some other kind of success stories recently.

Casey Dillman:

Yeah. In invertebrates, there were some droughts last summer or the summer before that in, in the, in, Tennessee, where the Tennessee Aquarium actually went out and got all of these fish from the creek because the creek was going dry. And so they have these fish in aquaria, that they're trying to maintain and save, so that when the water does come back, they can put them back out in the wild.

Laura Reiley:

So they're basically they only they only exist in captivity like like the rhino, white rhino or that kind of thing.

Casey Dillman:

Yep, yep, yep.

Laura Reiley:

Oh gosh. That's... that's...

Casey Dillman:

That's a lot of pressure.

Laura Reiley:

Precarious.

Casey Dillman:

Yeah. Exactly. Yeah. So how are the how is the health of, of, you know, natural history collections? Are we moving in the right direction or are we not? I mean, in in the world of fish, are we gaining ground or losing? In terms of like, what we know about the biodiversity or in terms of how the...

Laura Reiley:

Just actual specimen collection.

Casey Dillman:

We, in general, are contributing far less specimens to natural history museums than we have in the past. We have a paper published a few years ago looking at data. So one of the things that's happened with natural history collections is that we have digitized everything. And so we have these databases, and we can push that information out so that the public can see it. And then there are these aggregators that pull all of those different collections together. And you can search globally what we have in terms of the collections. And my colleague Vanya, who's the curator of the birds at the museum, and I and his brother put together a paper where we looked at invertebrates. How many — in vertebrates, not invertebrates — how many specimens of vertebrates are being added to collections annually? And the trend, you can see going doing this spike. And then it's just slowly tapered off.

Laura Reiley:

So is this a citizen scientist kind of problem, are we not... we're not pulling our weight in terms of collecting specimens?

Casey Dillman:

Yeah. And, you know, there's there's a thought that maybe we've already got these. Do we need more? But my counter to that is we definitely need more because things are changing environmentally, climatically, we're seeing that happen.

Laura Reiley:

You're saying species themselves are changing and adapting or...

Casey Dillman:

No, they're they're living through this thing that's happening right now. Yes. Species are changing. We see these changes over time. But we are able to — if we don't continue collecting during this time of change, I think it's a disservice to the animals that have been collected in the past that we're using with new technologies. And I like to think that in a hundred years from now, you know, who knows what sort of technologies people will bring to bear on questions. And if we don't have things sampled through that whole time, as more and more people are using collections, we have fewer and fewer specimens. So we need to continue adding those to the collections.

Laura Reiley:

So has digitizing allowed for more kind of open source or more sharing or more kind of kind of we're all in this together collections that, that, kind of get integrated across museums.

Casey Dillman:

Yeah. The National Science Foundation has this, had this program they called Thematic Collection Networks. And, when I first got here, we had a grant. There were 18 or 19 museums in the US that have this grant called oVert, which was the Open Exploration of Vertebrate Diversity. And it was the idea was to CT scan every genus of vertebrates and make that data publicly accessible, similar to the way that GenBank is a accessible database for DNA sequence data. When you sequence DNA and you publish a paper, most journals require you to put that data on this public warehouse so anybody can go look at it. Anatomy has been historically sort of isolating. People just sort of work on their own thing, and then they publish it. But we were trying to push this idea that it should be open source. And so we have this website that was created, before we started oVert, but it's out there that hosted all this, 3D CT data called MorphoSource. And it's a way of allowing people access to these, these data that are sometimes locked behind museum doors.

Laura Reiley:

Oh, that sounds incredibly exciting. So, I want to bring it around to kind of the optimism. And that's, that seems like a piece of it right there — is just the new technology's ability to share data like this. And maybe in some ways to preserve data...

Casey Dillman:

Yeah.

Laura Reiley:

kind of in perpetuity. What are the other things that kind of give you... or are exciting to you right now?

Casey Dillman:

Yeah. You know, one of the things that's really exciting is thinking about how many species are still out there like that we don't have a name for, and by building these networks of museums and working together, we can really sort of start to answer some of those questions. And there's a whole lot of excitement in my mind around species descriptions. It's not like the most exciting for a lot of people...

Laura Reiley:

But we don't name, after ourselves anymore, right? So there's not going to be the Dillman fish anytime soon?

Casey Dillman:

I think technically, by the rules of nomenclature, as esoteric as that sound, you can't name something after yourself. Somebody else would have to...

Laura Reiley:

But your friend could name it after you.

Casey Dillman:

Yeah.

Laura Reiley:

Okay.

Casey Dillman:

There is a slight push, I think, in the US to stop that. But I think that's a little sort of it's not up to the US to decide in that way what other people in countries are doing.

Laura Reiley:

Sure.

Casey Dillman:

And I think we've had this historical sort of heavy hand in that way of like, oh, it was fine when we did it, but now nobody else should do it, is the way I take it. And I think that as people are, especially like through the Global South, as more species are being described, they should be able to describe and name things however they would like. And it shouldn't be a dictation from somewhere else.

Laura Reiley:

Yeah, sure. So for, for people who are listening, who might be interested in this topic, kind of where do they start? What's what's a way to, get involved, learn more?

Casey Dillman:

Yeah. That's a great question, like, I think to the Museum of Vertebrates at Cornell is a little different than like a Smithsonian or American Museum, in that we have this major research collection, but we don't really have a public space. There's a small exhibit space at the Lab of Ornithology, focuses heavily on birds. Very well done. Very exciting. But you, you know, you don't go to this museum and see animals.

Laura Reiley:

We can't see the 1.3 million?

Casey Dillman:

You can. You just have to, you know, tour with a group or make reservations or contact us. Reservations sounds like we have a formal thing, but you just let us know and we can show people around. So, but to get involved with it, I think it just requires, like, reaching out to people, like, you know, if you're really passionate about something like, like I am with fishes, like my earliest memory is being in streams when I was like three. That's my earliest memories. I've always been drawn to it, and I think what you do is you just reach out to people and you talk about it, and you go to open house events and you interact, and we end up finding people that want to come in and volunteer and do things.

Laura Reiley:

It does feel like a great community to be in if you're interested in birds, fish...

Casey Dillman:

Birds, fish, amphibians, reptiles, yeah. And it's a supportive group for the most part of people. And yeah, it's a lot of fun to... When people are excited by what you do, it's natural to want to bring them in and have them sort of help out.

Laura Reiley:

So how about for, for kids? I think kids are, obviously, kind of I don't know, it seems to me like kids go through the dinosaur phase and then into the kind of yeah...

Casey Dillman:

Yeah, yeah, you —

Laura Reiley:

Yeah, fish frogs, etc...

Casey Dillman:

Absolutely. Yeah, I think, I think really again, it's a matter of, like, when these open house events happen, make contact with people. I think reading a lot, a lot of material online is becoming more and more available. You can spend time just at the library going through books and sort of getting into... And I get letters from, from middle schoolers saying, you know, I'm really interested in this. I would love to set up a time to chat. And so it's just I think being proactive is really what it is. And then as you progress towards college, you know, finding a, a school and a and a group of people who are like-minded. Cornell is is really unique, I think, in a lot of ways, because we have these courses called the ologies, which are like, herpetology, ichthyology, mammalogy, ornithology. So birds, mammals, amphibians, reptiles, fishes, and those courses have come and gone at some places. But Cornell has always had them and has always taught them. And we end up with a large number of undergraduate students that come here specifically because they're focused on understanding biodiversity through the ologies. And they end up finding their way out to the museum. And we have this really wonderful group of undergrads that spends time out there, working in the collections, conducting research, and otherwise building this sort of cohesive group of people that are just passionate about biodiversity.

Laura Reiley:

Wonderful. So I want to steal a page from, from Ezra Klein, who always asks his guests about book recommendations, and he asks for three. I'm only going to ask you for one.

Casey Dillman:

Okay.

Laura Reiley:

So what should people be reading if they're interested in fish and herps?

Casey Dillman:

Fish and herps... I actually will go a little more broadly and I'll say, Richard Conniff has a book called The Species Seekers, and it's about I can't remember the subtitle of it, it's like Fools and The Mad Pursuit of Life on Earth. Basically people who have gone searching for new species and the history of that and where it's at and it's it's a fun read. It's a lot of just the sort of the history of this science of understanding biodiversity.

Laura Reiley:

Oh. Wonderful. That sounds great. All right, so I did I did look up a bunch of your papers and, so it looks like you've done, a lot of work on black bass, Atlantic sturgeon, electric eels. I saw some rainbow trout, bony tongue fish. What are your favorite fish that you've done... done work with?

Casey Dillman:

My favorite fish. That's a great question.

Laura Reiley:

Not to eat, but just to study. Although maybe they go hand in hand, I don't know.

Casey Dillman:

Yeah, the the black basses and sunfishes are a cool group. I really like them. I like... North American freshwater fishes are really just a really interesting group in my mind. Most of it is endemic, meaning it occurs only in North America. And, given our latitude north, across that entire latitude from Europe and Asia, like, we have over, like, a thousand species and there's several hundred there. So we have this really smaller landmass with a really diverse fauna. And so thinking about how that comes into being is really exciting and understanding how Earth history is shaped, where things are distributed. And I yeah, I just think that it's really, a fun way to spend one's time.

Laura Reiley:

Great. Yeah. Well, Dr. Casey Dillman, thank you so much.