FE5.1 - Spiders Song (Part 1)

Are we are we going? We're rolling?

We're back.

This is the second windowless room I've been trapped in today.

The things we sacrifice for sound.

It's true. What's up Mendel? Why are we what are we doing here?

Well, Adam, I want to tell you a story that's really special to me. It's something I've been working on quietly since mid 2019. Basically, right after season one.

Okay, so this is, this is a long gestational process here, even by our standards, which are slow.

Yeah. I, so I don't know if you actually remember this, but right after we put out season one, we got an email. It was a criticism of our third episode, The Loneliest Plants, basically saying that we'd oversimplified the concept of biodiversity.

How does one not oversimplify the concept of biodiversity? But I do remember that email actually, didn't I respond to them?

Yeah, you went back and forth about genetic diversity versus species diversity. But for me, things didn't end in that email thread. Because I got the chance to sit down with the scientist who wrote to us.

I think that who I think I am is not quite who people know me as, or at least a lot of people know me as.

So this is Wayne Madison. And people tend to know him as an evolutionary biologist.

The work that I've done in evolutionary biology that's had the broadest reach is actually the computational side. It's the analytical tools that computer programs that help people analyze their data, because, of course, tools that help them do that really get a lot of traction in the field. And so a lot of people know me for that.

So Wayne, along with his brother, David, they developed software which is now widely used to understand the tree of life, or Phylogenetics.

Phylogenetics being... like the science of how a group of organisms is related to one another.

Exactly.

Their evolutionary branching patterns... that connect them — that connect us all.

Yeah.

I'm not an evolutionary biologist. But I do know that

So you probably have never had to create a Nexus file or used a program called Mesquite.

No Nexus is for crossing the border, and Mesquite is a tree from the southwest. As far as I know,

In this context, Nexus and Mesquite are to phylogenetics kind of what the mp3 and iTunes are to music.

Yeah, that's a good way to think about it.

And Wayne is the co author of both.

Oh wow.

But that's not actually the work he's most proud of,

The one thing that I'm the most proud of — and that I think will last the longest, as in hundreds of years — is actually my work as a taxonomist

Taxonomy. Okay, so we've started with phylogeny, now we're to taxonomy. But it's the taxonomists who put together phylogenies, right? They're the ones who figure it out and name all the things. And then sometimes very frustratingly, also changed the names of things that you got used to knowing as one name, and now they're something else... and then sometimes they change it back.

Yeah, right. Taxonomists are the people who literally make up the names. And more importantly, they describe and illustrate exactly what makes one species different from another.

And I'd never be able to identify all of these obscure grasses without them.

So way back then, I heard a story from Wayne, and it kind of changed my life. You know, looking back, I can say that it made me the person who I am today.

And who is that person, Mendel?

In a word, I am now a musician.

You are. It's awesome. I'm so excited that we can make music together for this podcast.

Yeah.

And yeah, I guess I hadn't thought too much about how or why you got there. It just sort of happened organically, from my perspective. Is this like your alter ego origin story? Is this the the genesis of Thumbug that we're talking about here?

You might call it the hatching.

The hatching... that... that sounds very organic.

Yeah. But you know that that's really just a tiny part of it. Because to tell that story, first, I need to tell you Wayne's. And it starts with the moment that put him on his path. It's a story of divergence and convergence; melody and rhythm; pattern and endless variation. From Future Ecologies, this is Spiders Song, Part One.

Broadcasting from the uceded, shared and asserted territories of the Musqueam, Squamish, and Tsleil-Waututh, this is Future Ecologies: exploring the shape of our world through ecology, design, and sound.

Our story begins in 1970, when Wayne was 12 years old.

Burned into my memory is this one day. We were in the Rocky Mountains, my family, my brother and I.

They were on a trip through Kicking Horse pass

Not too far from the border between Alberta and British Columbia, just traveling through the mountains.

While they were there, Wayne found himself at the headwaters of a small mountain stream

That has a really peculiar thing happening to it, or at least it was really peculiar to me as a 12 year old. You follow the little creek along, it's going downstream. And at one point, there's this pile of rocks there, and the stream splits in two.

One side flowing to the west, the other to the east.

It's not like a normal stream that you think about where you have tributaries that come together. This was a case where it split. And there's a little plaque there, and the plaque explained

That this stream was positioned precisely on top of the great continental divide. From this point of divergence, the two halves of this creek would end in different oceans.

The left half of the split continues, eventually joining other creeks becoming rivers and going to the Pacific Ocean. The right half continued down the other side, into Alberta, and eventually going to the Arctic Ocean. And I remember looking at that, and thinking, "Whoa, just imagine the water is coming, and two little bits of water that are just a millimeter apart, strike this pile of rocks, and the one little bit

So this place was called Divide Creek.

And, of course, I realized that life is full of Divide Creek moments. Every one of us has these moments when some little different decision that you could have thought of, or some little different bit of chance that might have encountered you could have led you on a completely different path in your life.

One such moment would come for Wayne the very next year, on the shores of Lake Ontario.

And as we were there on the shore, a mat of grass floated by — presumably some nearby house or something had mowed their lawn and thrown it onto the lake. We we didn't compost back in those days. And on that mat of grass floating by was a spider. She was a fairly small spider as spiders go. But she looked up at me. And it was the fact that she looked up at me that was I think the thing that I noticed so much, because I'm not used to little things in the world paying attention to

She was about as cute as a spider can be. Tiny in almost every way, except for a big pair of eyes.

So of course, not only did she look up at me, but she was looking around at things in general. Like when I had her on my hand she looked around.

She would tilt her whole body to look at different things. Clearly paying attention to the world around her

With how she looked around, with obviously her really good vision, she felt more like a little cat than like a spider. You know, at that moment I felt connected to her as individuals. It was a connection about a common way of seeing the world. But as I became a biologist, and I learned more about evolution, I came to understand that we were connected, of course, by more than that — because we're all part of the same

That is to say that once upon a time, the ancestor of Wayne and the ancestor of this tiny spider were siblings — both part of a population of ancient animals, probably small, bilaterally, symmetrical wormy things living in the ocean, when something happened, that caused that one population to split into two.

That was a Divide Creek moment. So that for whatever reason, one of the subpopulations became isolated, and it evolved and changed. And eventually it diversified into many, many thousands, and in fact millions of different species, including snails, and insects, and spiders, and so forth, and including, therefore, the spider that was on my hand

And so he kept this spider as a pet, and fell in love. And of course, as a budding taxonomist, the first order of business was to give her a name.

So I had to first of all figure out what she was, in terms of human names, what species. So I went, and I looked in a bookstore. They had the little golden nature guides, and there she was Phidippus audax. That was her species. But because her name was Phidippus audax, her species name, I called her Phiddy. So she was Phiddy.

Audax, a species in the genus Phidippus, in the family Salticidae — a family of tiny arachnids, also known as jumping spiders.

The rest of that summer, I started noticing jumping spiders on houses, on bushes, on fences on trees, and I realized that there were lots of different species.

They were all recognizably related.

They all shared these great big eyes, they all reacted to the world like a cat. And yet,

They were also radically different from each other. With all sorts of spectacularly weird shapes and colors.

Some of them were small and striped, some of them had metallic pink rear ends, some of them had green bits, some of them are longer and thinner, and so forth. It was an incredible diversity, all of them being jumping spiders, all of them having this behavior.

So you you said that they come in all different shapes and colors, but um, do they also come in all different sizes?

No, basically, as a rule, no jumping spider is very big. And they're all harmless to humans. You know, most wouldn't even be half as wide as your pinky nail.

Got it. Okay, these are not not huge spiders.

Yeah, they're teeny tiny.

One of the things that I learned that summer was that you don't have to go to exotic tropical places to find absolutely gorgeous, spectacularly beautiful biodiversity. Here in Vancouver on the beaches, There's this one species, Habronattus americanus, that the males have these bright red pom poms. And the face is this metallic mauve color. Absolutely spectacular. They're so beautiful. And yet no one knows that they're there because they're only half a centimeter

And as it turns out, jumping spiders — of which Phidippus and Habronattus are just two subgroup — this is the most diverse family of spiders on the planet at around 6000 described species that accounts for nearly 15% of all spiders.

Oh, wow. That's a lot of spiders. Good thing they're small.

Yeah. And this is the group that Wayne focuses on as a taxonomist, so we're going to spend the rest of this episode talking about biodiversity in general by talking about jumping spiders in detail, because they're just an amazingly illustrative microcosm of evolution itself.

Okay, okay, we have these colorful, beautiful charismatic divers, but very small spiders that make up a fairly significant proportion of all spiders. But just backing up for a sec, jumping spiders...?

They are called jumping spiders because they jump. So I tend to think of their eyes as being their most distinctive feature. But their jumping is used in combination with their eyes for their prey capture behavior. They don't build a web to catch prey.

Wait, what is a spider if it doesn't build a web? Do they still spin silk?

So they use their silk for little cocoons that they sleep in. They use silk to wrap their egg masses. They use silk as these little draglines that they carry behind them, sort of like a rock climber, in case they fall. So they see very well, they sneak up on things, and then they pounce using a really well executed jump.

Oh, they really are like little cats, aren't they?

Yeah, you know, in in a number of ways, actually. For example, those two big front facing eyes — thanks to those jumping spider vision is even sharper than a cat's.

Which is pretty incredible for something that small, because they're running against the physical limits of how small the pixels can be, so to speak, and still get enough light to detect the signal.

But there's at least one major distinction between cats and spiders.

Like... like besides the number of legs?

Yeah. And that's how they jump. Cats basically jump in the same way that we do with muscles moving bone and joints to push off of the ground. But jumping spiders don't have big muscley legs.

Right? How does it... how does it work?

It turns out that the power for the jumping doesn't come from the legs themselves. The power from the jumping comes from blood pressure rising quickly and squirting into the legs and propelling the leg straight.

The powerful muscles that allow these spiders to jump aren't in their legs, but in their heads.

And so it's actually a hydraulic jumping mechanism that they use.

So in order to jump, they clench the muscles in their head, push a bunch of blood into their legs, and off they go,

They can jump quite precisely. They are known to be able to jump and nab flies flying by. So they can nab flies out of the out of the air.

But remember, these guys are teeny tiny.

The furthest they can jump that I've ever seen is maybe about 25 centimeters. And that's an Olympic jumping spider jump.

Usually their jumps are just a few centimeters.

Little hops.

But that precise control also allows them to do more than just jump. They sing, and they dance.

You're joking.

This amazing vision is not just used by the spiders in catching prey, but it's also an opportunity for them to communicate with one another. The beautiful colors of these males and the complex ornaments are used in these courtship dances — where the males display in front of the females and the females use their excellent vision to watch the males. In some species of jumping spiders, like the one that Phiddy belongs to, the courtship behavior is

So just for a couple of examples, jumping spiders have dance moves like the tick-rev and the foreleg wave.

Oh, these have been named.

Yeah. Well, Wayne and his colleagues named them.

Oh, got it.

Do you want to try them with me?

I would love to try them with you.

Okay, so we're going to do the tick-rev. So bring both your front legs forward, up and over your head.

You mean my... you're talking about my arms?

Yeah.

Okay.

Okay. Now bring your wrists down, so your hands point forward.

Yes.

Now, pop your hands up. That's the tick. Tick!

Tick!

Now, flap them forward, up and down as fast as you can. That's the rev. Revvvvvvvvv Revvvvvv

I think I've done this in aerobics class before.

All right. All right. One more time. Tick!

Tick!

Revvvvvvv

Revvvvvvvvvvv

Tick!

Tick!

Revvvv

Revvvvvvv. Aaaaa I love it.

I'm glad. So let's keep it going and we're going to do the foreleg wave. Bring your arms down a little.

Okay.

Keeping your hands pointing forward.

Okay.

But instead of ticking and revving, wave your hands in circles from the wrist.

Which... which direction do I wave my hands in here? Do I wave them together or opposite directions?

Well, different spiders have different dances. So whatever feels right.

There's almost as much variation among jumping spider species in their dances as there is among their appearances. Of course, they've got eight legs, they've got these palpae up front, and they've got an abdomen. And so there are lots of things that they can wiggle and move. So they'll rotate their little pelvis in little circles. They'll flick the front legs, they'll shuffle the third legs,

And these tiny, intricate dances are taking place all around us all the time.

This is happening in people's backyards all across North America. Like they're just these little birds of paradise that are hopping around people's backyards.

Okay, so they dance. And you also said that... that they sing?

In a manner of speaking, they vibrate.

It almost sounds like a cat purring

Yeah, or a motorcycle.

If a cat was a motorcycle!

That clicking is not actually being done by the first legs, even though it looks like it might be. The first leg simply are synchronized with the part of the body that is making

And because of that, you can't really hear these songs with your naked ears, which also makes them really hard to document. Instead of a microphone, these recordings were made with a laser that measures changes in the surface deflection of whatever the spider is standing on.

So jumping spiders don't really have great ears in terms of anything that would hear through the air. And primarily, they sense vibrations through the ground, so that they're feeling the ground shaking by how it affects their legs.

And despite accounting for nearly 1/6 of all spider species, jumping spider songs are almost completely undocumented. When people have heard about jumping spiders, they usually know about the dances, but almost never about the songs. Both the songs and the dances are part of the same courtship performance. Each dance motif is paired with a

That's so wild.

And you could say the songs are pre-programmed. The structure of them is pretty consistent between performances. And they're similar between closely related species. But there's evidence that female jumping spiders prefer... novelty! They respond better to a song and a dance that they haven't seen a million times before.

Yeah they're just like us.

In some ways. One thing I think it's particularly amazing is that in the most complex performances, there are certain sections where individual spiders will apparently improvise — almost as if they're covering a jazz standard.

Within a group of say 5, 10, 20 species, they're all playing basically the same genre — they're all playing jazz, basically, right in a particular genre of jazz. But they'll use the elements with different numbers of repetitions, or maybe a little extra note in there or something like that. But it's the same basic thing. Whereas the next group over will be big band.

And when jumping spiders evolve to be showy, they really go all out.

So the most complicated colors and ornaments are held by the species that have the most complicated movements, and the most complicated songs.

The ones with the most complex songs can perform for over an hour! And again, we're talking about a spider that might just be the size of a pea. So while we don't see a huge amount of creativity across individual spiders,

the creativity comes at the evolutionary level, as natural selection generates new variants of the displays. And so there is creativity in the system, but it's more at the broad level across millions of years among species, and not at the actual individual spiders inventing new little songs.

But when we step back to observe the group of species...

The fact that the lineages that are doing this, that are holding these patterns are also beautiful, each in their own way, that each has this amazing set of structures and colors, and behaviors and noises and everything,

You might say, nature's creativity,

It's just stunning. Pretty early on, as I was getting into jumping spiders, I started drawing them. And for me, it was not only just an expression of an artistic side that I've always had, but it was also a way for me to celebrate these organisms that I just thought were so cool. Eventually, that turned into biological illustrations for the sake of documenting the differences among all these species. And I, of course, I built up a bigger and bigger library of all these drawings.

That is, although they were very different, there was something in those differences that was recognizable.

You know, maybe it's easier to think about it was something that people know, like an orchid or something like that, like you look at an ark and you say, oh, that's an orchid, right? And you can look at a different species of orchid. And it's like, oh, it's clearly an orchid, but it's different, right? And you get to see what you can compare. Oh, that's that bit. That's that bit. But you can see how those bits differ. And so you start to notice that this is variations

But this evolutionary dance is more than just endless variation. Because sometimes creeks divide, and then later reunite. That's after the break.

You know, these Divide Creek moments in evolution where a lineage splits in two, and then each diversifies. You look at one of the points, of jumping spiders, and another point, humans — we're so different in so many ways. You might think, "Oh my gosh, evolution is just all this chaotic diversification." And then you look within jumping spiders and how much diversity there is in jumping spider dances "Oh my gosh, it's just constantly diverging,

So understanding the dance of evolution isn't just about appreciating variation. Sometimes organisms will each take different evolutionary journeys, and still end up in a remarkably similar place. In a word, they converge.

Right. Convergent evolution.

Right, yeah. And maybe you've heard that there's kind of a meme about how all sorts of animals keep evolving into crabs.

It has been brought to my attention, Mendel, that we are all heading inevitably towards crab.

Crabs have happened at least five separate times now. So to kind of build on our metaphor of Divide Creek, we've got these two blobs of water, they hit a rock in a stream, go their separate ways and find themselves in different oceans on opposite sides of the planet. Then maybe eons later, subject to the wind and the whims of the currents. They are eventually reunited.

And eventually, both of them will be crabs.

Yeah, maybe.

Am I following?

Yeah, yeah, but, but in jumping spiders, you can see a whole set of really vivid convergences. For example, depending on where certain species live, you know, either mostly on tree trunks or in vegetation. They'll take on certain typical body forms.

Sure.

But there's also apparently a really strong pressure for a jumping spider to pretend to be an ant! 14 different genera of jumping spiders from all around the world, separately evolved into near perfect ant mimics. Their bodies become long and skinny. And sometimes they grow whole fake heads and eyes, or they'll wave their forelegs around like antenna.

You're saying that while the rest of us may be on an inexorable trend towards crab, jumping spiders are headed towards ant.

Yeah, some of them, at least. And this ant mimicry has happened over and over across jumping spider evolution. But it doesn't stop there. Some jumping spiders have independently evolved color vision.

Jumping spiders can see color, but in a limited way for most species.

So most spiders can only see green and ultraviolet light

Sort of the equivalent of a human being colorblind. There are though some jumping spiders that have evolved a color vision probably as rich as ours.

What's really incredible is that they've accomplished this in different ways.

But only in a few groups. One of them is Habronattus, a group that I've looked at a lot.

Habronattus is a mostly North American genus, also known as the paradise jumping spiders, many species of which have red ornaments on their legs or their faces, despite the fact that they have exactly zero photoreceptors sensitive to the color red.

But instead, they've sort of hacked their green photoreceptors in a way to be able to see red by putting a red filter over some subset of those green photoreceptors. On the other hand, some other groups of jumping spiders have a different solution to a richer color vision. And so the peacock spiders, genus Maratus have instead done it in sort of the more traditional way to add colors, which is to add extra sensitive photoreceptors.

Incredible.

And remember how you asked which way to wave your hands while we were doing the spider dances?

Yeah?

There there are actually convergences there as well. Several different lineages of spiders have independently evolved asymmetrical dance moves, despite theories that sexual selection favors symmetry.

Are the ones like in the southern hemisphere, like they go one way and the ones in the northern hemisphere go the other way?

I don't think so.

Has anyone checked?

Probably not? That's a PhD right there. But speaking of sexual selection, it could be that many of these other evolutionary patterns, especially the ones that seem to be important for these courtship rituals, are connected to another convergence. Just one that's a little harder to see...

Their sex chromosomes.

Their sex chromosomes. Stay with me here.

Well, you said the word sex, and then you said the word chromosomes, so I'm torn. I hate to admit it, but my, my cellular bio is a little rusty.

Well, if I may?

By all means,

In your body, inside the nucleus of every cell, you've got a copy of your DNA, and that DNA is tightly coiled up and split into separate chunks. Those chunks are your chromosomes.

Okay, yeah, I can keep up with this.

Each chromosome is part of a matched pair, half your chromosomes are from one parent, half her from the other.

I'm with you.

The overall set of chromosomes is shared by every member of your species, except for the sex chromosomes, which occur in two different forms so called X and Y. Without getting into gender, which is a subjective experience slash social construction, or the spectrum of genetic exceptions to this binary, sex chromosomes in mammals, humans included, are typically an XX pair in females, and typically an XY pair in males.

Yeah, the X chromosomes, which are the nice long, fully formed ones, and then the Y one, which is like the runty little fragment of a chromosome.

Yeah.

Okay. This I understand — humans, XX, XY. That's us. What about the jumping spiders?

Well, most spiders, you can think of it as being a little bit the same. I mean, obviously, the the basic idea of having chromosomes it's the same as with mammals. The way it works in mammals is that that Y chromosome typically doesn't do a lot. And so you could almost dispense with it, right? You could always imagine the few functions it does, they move somewhere else. And then you've just got the X all by

Within just this one genus of Habronattus, there are four different versions of male sex chromosomes — from a single X up to three X and a Y.

Okay, I get it sex chromosomes are weird. But what's the relationship between this and all the other convergences we were talking about?

Okay, so I, I want to preface that that this part is theoretical, and doesn't necessarily apply to mammals and humans. But it could boil down to a sexual conflict between the different versions of certain genes.

What do you mean by that? So males and females are really different in all these regards.

Of course, when we're talking about these And as each of these features of males and females were evolving, courtship features, the dances and the ornaments and songs and so forth, males and females are different in these — males have them, females don't. What the females have instead is probably there's a really good chance that there was a time, a moment this whole array of invisible preferences that we can't see, right? So they've got their own things, but they're harder to see.

So a Y chromosome could be a way for the spiders to develop sexual dimorphism. And that would give you colorful dancing males and less colorful but highly discerning females, just like you see in many birds.

No, not exactly. There are lots of sexually dimorphic jumping spiders that don't have a Y chromosome. In fact, it's actually really interesting here, because it's the exception, not the rule.

So for what it's worth, it turns out that when you look at the data for animals, there is only one other case that seems to have even close to this density of Y chromosome evolutions. It's some lizard case. But it's like this is like hugely rare to have this many origins in a small phylogenetic space.

But this mechanism could play a part in reinforcing the especially strong dimorphism that we do see in certain genera, like Habronattus.

One of the hints, even though we don't have really good data, that this is what's happening in this group — when you look in Habronattus, those groups of species that have the most complex courtship dances are in fact those that seem to have evolved the Y chromosome most often. And the spectacular thing is when you see convergence, as you do with jumping spider dances, and chromosomes and so forth, is that you start to realize that there are certain repeated

And like a symphony, evolution isn't completely random. But it also isn't completely predictable. There are similar evolutionary sequences, motifs and melodies that come again and again. There's harmony, rhythm, repetition. And yet, there are surprises everywhere. To Wayne, this was a shift in perspective not unlike looking up at the stars at night, and realizing that the Milky Way isn't just a dusty stripe across the sky, but it's something gigantic, that we're all inside of.

What if somehow I could hear it?

That's coming up in part two. Music in this episode was produced by Elisa Thorne, Curtis Andrews, West McClean, Patricia Wolf, Sunfish, Moon Light, and me, Thumbug. All the jumping spider audio recordings you heard came courtesy of Dr. Damian Elias and his lab at UC Berkeley. This series of Future Ecologies was produced by me, Mendel Skulski, with help from my co-host, Adam Huggins and our