Episode 61: Genetic Control of Courtship Behaviors in Flies and Roaches (Happy Belated Valentine’s Day)

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An illustration of a female and male fly of the species Drosophila melanogaster separated by an emoticon heart, as if to suggest "female D. melanogaster loves male D. melanogaster".

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Transcript

Charles 0:23
Hello and welcome to Assigned Scientist at Bachelor’s. I’m Charles and I’m an entomologist.

Tessa 0:28
And I’m Tessa and I’m an astrobiologist.

Charles 0:30
And today it’s just the two of us for an episode that was going to be a Valentine’s Day episode but then I procrastinated doing research and Tessa forgot that we were recording.

Tessa 0:42
Yeah, pretty much.

Charles 0:43
But now it’s just…

Tessa 0:44
I mean, close enough.

Charles 0:45
Close enough, days are fake. So I started doing research for a Valentine’s Day episode thinking, and my initial thought was, let’s do more weird bugs acts, because that’s always a crowd pleaser. But then I thought – Valentine’s Day is not, you know, a Dionysian celebration of excess, it’s a day for romance. So then I thought all look into mating rituals, like courtship rituals, of different insects. And the first thing that I thought of was this very well described courtship behavior in the species Blattella germanica, or the German cockroach.

Charles 1:28
But while I was researching that, I found a paper addressing sort of genetic determinations of sexual differentiation in insects, genetic control of behavior, and also how well established in the insect family tree these genetic controls of behavior are. And that is what I will be telling you about today. Specifically, the fruitless gene, originally described in Drosophila melanogaster, and then later manipulated in Blattella germanica.

Charles 2:04
So basically, the fruitless gene was identified in Drosophila melanogaster, because as we’ve talked about before, Drosophila melanogaster is like THE model organism for genetics, right?

Tessa 2:17
Yep.

Charles 2:17
They’re commonly known as quote unquote, fruit flies. Those in the know might actually call them vinegar flies, but if you’re actually in the know enough to call them vinegar flies, you’re probably just going to call them Drosophilidae anyway, because you’re an entomologist. And I always have to bring this up because my master’s work was on the fly family Ulidiidae, which is in the superfamily Tephritoidea, named for the family Tephritidae. And those are the fruit flies. And I think, you know, we can get into sort of the philosophy and politics of insect common names, but just looking at it – fruit flies as in Drosophila as in Drosophilidae are known as fruit flies because they are often found when you have like rotting fruit in your kitchen, right? Because they, like many other flies, lay eggs in rotting substrates – like dead stuff, basically, right? This is very, very common in flies. It’s kind of the defining sort of life characteristic of true flies really, where they love to lay their eggs in very soft environments where the maggots can hatch out of the eggs. And then they’re kind of just living in a daze of soft, high nutrient sludge until they pupate.

Tessa 3:37
Usually, like in like labs, it’s usually like potatoes.

Charles 3:41
Yeah, so you know, that can be fruit, it can be poop, it can be bodies, you know, whatever you don’t like. Whereas Tephritidae is primarily phytophagous, and this is all kind of beside the point, but it’s – nobody respects true flies enough, and I’m gonna change that. And if I can’t change it, I’m going to make everybody listen to me talk about it. Anyway. But essentially, primarily phytophagous meaning that they don’t just colonize dead plants, they colonize living ones, baby. So tephritids will actually lay their eggs inside living plant tissue. And because of that a lot of tephritids are well known, and well hated, pests on agricultural crops, right?

Tessa 4:26
Right. Yeah, I kind of figured that would be the natural result of that.

Charles 4:29
So my feeling is, tephritids really deserve the name of fruit flies, because to drosophilids, they could be laying their eggs in any old thing. Whereas tephritids are laying their eggs specifically in living fruits. Uh, thank you for coming to my TED Talk. But actually as an as another point – tephritoids are interesting because most flies, they just all have lost the true ovipositor but tephritoids have re-evolved an extension of their abdomen to serve as an ovipositor. So it is not the same string, it is not like the same physical structure that exists ancestrally that…

Tessa 5:12
Right, it’s a different one that’s been repurposed.

Charles 5:14
Yeah, it is basically, like – we have as humans lost our tails. But it’s like, what if we evolved, so that just an extension of our butt looked like a tail? And that’s what tephritoids have basically done. Anyway, so the fruitless gene was identified Drosophila because – uh, not because it’s unique to Drosophila, but just because Drosophila, specifically Drosophila melanogaster, is the species that everybody was doing all of this genetics work on. I was actually, I was doing research for this episode, and I was looking at it, and I was like, man, a bunch of these early papers identifying specific genes in Drosophila are from the 90s. And then I was like, Yeah, ya nerd, because that’s right after we developed PCR.

Tessa 5:58
Right, right. That’s when everybody was sequencing like mad.

Charles 6:00
That’s, of course, that’s what it was, because that’s when everybody could do it. Yeah, so the fruitless gene, in, identified in Drosophila melanogaster, is known to control courtship rituals. So Drosophila melanogaster of… males have this whole sequence of behaviors that they will do to initiate copulation with females of their species. And according to the description on the GeneBrief, on the website of the Society of Developmental Biology, quote, “fru encodes a set of putative transcription factors that promote male sexual behavior by controlling the development of sexually dimorphic neuronal circuitry.” In other words, transcription factors being proteins which control the transcription part of the central dogma of molecular biology. So, the central dogma being – DNA is just transcribed into RNA. And then RNA is translated into proteins. And that is how gene expression works.

Tessa 6:52
Right.

Charles 6:53
You know, varying parts of that process leads to different gene expression. And so fruitless, along with other genes, like sex lethal and double sex, are part of this cascade controlling sexual differentiation in Drosophila. Where – insects do also use… so like humans, as we’re all taught, use chromosomal sex determination, right? Where, obviously very simplified, but if you are XX then you’re female; if you’re XY than you’re male. [Deliberately mumbles] Simplified, simplified, simplified – so this is trans podcast, whatever, right?

Tessa 7:29
Yeah, yeah, that’s a whole other episode.

Charles 7:30
It’s a whole other episode – that, which we did an episode about.

Tessa 7:33
Yeah.

Charles 7:33
Which I will link but the, the way that that works, really, is that during embryological development, the SRY gene from the Y chromosome, essentially is like you’re gonna do this, or you’re gonna do this. And then the sort of series of sexual changes related to sexual differentiation happen because of the production of estrogens or androgens, right, where like, if you have testosterone, then this will happen – if you have more estrogen than this will happen, et cetera, et cetera, et cetera.

Charles 8:04
But that is not how it works in insects, where insects do have a chromosomal component… different groups of insects have different methods of sex determination, because I mean, it’s a huge group of animals, right. But in humans, you know, we have, we have this one gene, which then leads to whatever and then a lot of the actual sexual differentiation during development is controlled by hormones, whereas in insects, and specifically in Drosophila, specifically, specifically with Drosophila melanogaster, it is not that this one gene leads to the production of specific hormones, which then control further differentiation, it is that specific genes related to, you know, the chromosomal method of sexual determination lead to these alternative splicings of different genes, which do or do not produce functional proteins and putting that in, hopefully, a more accessible way…

Charles 9:03
When… earlier I mentioned the central dogma of molecular biology, right, where DNA is transcribed to RNA, and RNA is translated to proteins, which are basically just… meaning DNA is what we think of as your genetic code. That is what you have inherited from your parents, that’s kind of the like, the blueprints of whatever. And then to make those blueprints into the house that is your body, uh, first… [pause] you know, that’s a metaphor that really stalls out because there’s kind of no intermediate step between blueprints and building in the way that there is between DNA and proteins. But basically, you have DNA and then the DNA gets transcribed into RNA, which is just another form of nucleic acids, right? And so RNA then is used to translate into proteins where like going down reading the RNA, we have these three base pairs, and then you get these whole big structures of proteins based on all of the different amino acids and how they’re connected to each other, and the order in which they’re translated.

Charles 10:14
And then the idea here with alternative splicing is that males and females have like the same whole gene fruitless, but because of whether they have been determined to be male or female earlier on in development, other genes, double sex and sex lethal, again, which sounds so metal… the way that those genes have been transcribed and then translated results in functional proteins, which then control how fruitless goes through that whole process from DNA to proteins. Where in males, it will go this one route, and then in females, it will go this other route, but it’s not because they had they had like different copies of the same gene, it is because earlier in the process of like sexual differentiation, other genes have been spliced, and other proteins have been made, such that that kind of keeps the male or female developmental pathway rolling forward. Hopefully that makes sense.

Tessa 11:15
Yeah, that makes sense.

Charles 11:17
Genetics, you know what I mean? Essentially, in the 90s people discovered, first of all, they discovered fruitless as a gene, and then they were figuring out what it did, they do what all those wacky geneticists are always doing, which is they created and then mated and experimented on etcetera, etcetera, mutants, and so they found, quote, “When fru mutant males are grouped together, they form male male courtship chains in which each male is simultaneously both courting and being courted. All mutant combinations show some male male chaining.”

Tessa 11:52
Interesting… the geneticists are making the frickin fruit flies gay.

Charles 11:56
Alex Jones was so upset about the frogs, he was looking in the wrong place. And so because of research done on fruitless, and mutations thereof, it has come up repeatedly as an important piece of evidence in discussions over to what degree complex behavior is learned versus genetic, given that there is apparently a very straightforward relationship between the fruitless gene and courtship behavior, including abnormalities in some aspects of courtship, using appendages that are otherwise unaffected. So for example, part of the stereotyped courtship behavior of Drosophila melanogaster males towards females are a wing display described in one paper as quote, “singing a species specific courtship song by extending one of his wings and vibrating it.” And so they, the mutants, the fruitless mutants fail at doing this aspect, but it’s not a mechanical or a physiological problem with their wings, because their general ability to fly and other uses of wings are not affected. It is specifically the failure to perform that courtship behavior.

Tessa 13:03
I mean, are we sure that this is like because they’re male-male, or is it just because they’ve got no game?

Charles 13:08
I mean, I think it seems to be kind of be both.

Tessa 13:10
Okay, gotcha.

Charles 13:10
Yeah, yeah, yeah – where like, yeah, there are different aspects, I think that are. And this is deeper into the sort of the genetics literature than I felt it was responsible to go given that I have a bunch of other stuff that I need to be doing. But it seems like different specific mutations result in a variety of ways that males can fail. So it’s not just turning the frickin bugs gay, it’s also like inability to initiate courtship behaviors or inability to complete the whole stereotyped sequence.

Charles 13:39
And then also, interestingly, in 2005, several researchers completed quote, “gene targeting by homologous recombination to generate alleles of fru that are constitutively spliced in either the male or female mode,” just meaning that they like, took flies, and they did some genetics trickery, right? So that otherwise quote unquote, normal females would have the males splicing pattern or fruitless and otherwise quote, unquote normal males would have the female pattern. And they found that in the quote unquote, normal females splicing in the male pattern resulted in those flies demonstrating typical courtship behavior towards other females and males spliced in the female pattern, the loss of courtship behavior, and, quote, orientation, meaning that they then were doing courtship towards males rather than females.

Charles 14:28
So that’s kind of a general introduction to the fruitless gene. And just the idea that there is this gene that is very well documented, very well understood, lots of research about it in Drosophila melanogaster, which is known and has been demonstrated to control the specific stereotype courtship behavior. [interstitial]

Charles 14:52
So then, taking a step sideways briefly, I would love to discuss Blattella germanica, also known as the German cockroach. I would ask if you have seen one of these cockroaches before, but the answer is almost certainly that you have.

Tessa 15:06
Oh, yeah, yep.

Charles 15:07
But you may, you probably didn’t recognize it as the quote unquote, German cockroach when you did.

Tessa 15:14
Potentially, I don’t know how many other varieties that are here in Phoenix.

Charles 15:17
Uh, a variety. So Blattella germanica belongs to the extreme, extreme – I’ll say it again – extreme minority of cockroach specie which are established as quote unquote pests, where there are over 4000 described species of cockroaches, not even including termites, which is another episode for another day, but over 4000 species, and only like 30 of them are really well established as, quote, unquote, pests in human homes. And yet, all anybody ever wants to talk about.

Tessa 15:33
They’re getting a bad rap, man.

Charles 15:54
It’s unbelievable, especially because here’s, here’s my little bugaboo. It is very, very, very, very, very, very, very, extremely common to see cockroaches brought up as a health concern, because of their ability to mechanically transmit pathogens – mechanically not being, you know, they’re getting in a forklift and transferring… but mechanically, as in pathogens get on them, they get on other stuff, the pathogens get on the other stuff, right. But a lot of times when people bring this up, they either don’t justify it at all, or, they appeal to like very controlled experimental settings in which it is demonstrated that they can do this. But I the evidence that cockroaches are demonstrably a significant source of pathogen transmission through them walking through pathogen somewhere, and then walking through another area and getting them somewhere, and then that being a significant source of health problems… I’m gonna say it – if you’ve got it, send it to me, because I haven’t seen it.

Charles 17:04
And I will say it’s, you know, not to minimize cockroaches as a potential health concern, because particularly if you have large aggregations, cockroaches do produce allergens, which can upset anybody but are especially a problem if you have some kind of respiratory condition, for example, if you’re asthmatic, but! Like, in my previous apartment, I was living on the ground floor and I had two doors, right. So sometimes I would find a random cockroach in my apartment, inevitably. But I didn’t freak out about it. First of all, because I’m the number one friend of cockroaches and they know –

Tessa 17:39
Right, right

Charles 17:39

  • that I love them. And then also because a singular cockroach coming into your house from outdoors, even a couple of cockroaches that you just see sometimes, you don’t need to worry about it.

Tessa 17:50
Yeah, yeah, it’s only like, again, there’s like massive aggregations of them.

Charles 17:54
Massive aggregations are a problem, but if you have the conditions for massive aggregations of cockroaches, you have underlying issues…

Tessa 18:02
I was about to say, you’ve probably got other bigger problems to worry about first.

Charles 18:06
Where it is a part of the problem that you’re facing, but it is not the only problem.

Tessa 18:11
Yeah.

Charles 18:11
Like if you just see a cockroach sometimes in your house.

Tessa 18:14
Right.

Charles 18:14
Respectfully…

Tessa 18:15
That’s not going to do it, yeah.

Charles 18:16
Get over yourself. So back to Blattella germanica specifically, it is one of the sort of the classic pest species and it has a basically a distribution all over the world, but pretty much exclusively in close association with humans. And they are small, relatively delicate looking yellow-brown roaches that are recognizable because they have these two large distinctive dark stripes on their pronotum. In Blattella germanica, it’s one of those species that carries ootheca, or egg case, around hanging at the back of the abdomen, which is just always very funny. Because it’s like… imagine if – today is just a day of horrifying anatomical analogies – but like imagine if instead of just giving birth, humans had the whole amniotic sac just hanging out of the vagina for a while. Right? And then when the baby was finally done, it just kind of burst forth. That’s kind of that reproductive adaptation in all of these cockroaches that have ootheca just hanging… their abdomen is just partially open for a while. And as we’ve said, we’ve discussed before the ootheca in cockroaches typically looks like a cute little leather clutch purse, and much like a clutch purse, it kind of opens at one side and all the treasure comes out. And by treasure I mean a bunch of little cockroaches, little immature cockroaches will emerge when the egg portion of their life is over.

Charles 19:42
Much like, but not on quite the same level of Drosophila melanogaster, Blattella germanica is a very well established model organism and there’s a huge amount of research on Blattella germanica, partially because it is financially and culturally important as a quote unquote pest species, but also I think part of why there are so many studies on Drosophila melanogaster is that there are already so many studies on Drosophila.. like if you want to dig deep into the genome of an organism, are you going to choose an organism that nobody has sequenced before, or are you going to choose an organism that already has hundreds of papers published on its genes?

Tessa 20:21
Right, right.

Charles 20:22
If you already know a lot about an organism, it’s easier to narrowly identify specific, interesting biological questions, because there’s all of this general information that’s already kind of taken care of.

Tessa 20:35
Right, you don’t have to, like reinvent the wheel.

Charles 20:36
Right, exactly. And interestingly, Blattella germanica, also like Drosophila melanogaster, has a very well established, well documented courtship ritual between the males and the females to initiate copulation, which was actually initially described like 100 years ago. People have known how Blattella germanica gets down for longer than almost any, any living person, right. And so a description from one paper quote, “in an encounter the male touches the female with the antennae, raises the wings upward and then turns around 180 degrees, thus exposing the tergal gland to the female. The secretion of these glands stimulates the female to mount the male and feed and while the female feeds on the tergal gland, the male pushes the abdomen under the female and clasps her genitalia with his left phallomere to accomplish genital connection.” Putting that in, it may be more accessible language, essentially, you start out with two cockroaches. One of them is… he was a boy, she was a girl…

Tessa 21:33
Can you make it more obvious?

Charles 21:34
You know, exactly. What the male will do is establish, using the antennae, that he’s dealing with a female cockroach, because Blattella germanica, unlike fruitless mutants, definitively said No homo. And so the male establishes that it’s a female, and then raises his wings up and exposes the upper part of his abdomen. And the tergal gland – basically, a tergite is just what we call one of those segments of the abdomen. And so the tergal gland is just on one of those segments. And I did, I did, I spent time looking up the actual contents of the secretion of the tergal gland. And I found it described in one paper as a combination of quote “oligosaccharides, lipids and proteins,” which basically just means – I dunno, nutrients. You know, where saccharidess – sugars; lipids – fats, proteins… protein. And the female is like, well, I’m an insect, and therefore always under pressure to find sufficient food to keep my life continuing. I’m gonna eat this,

Tessa 22:35
Right.

Charles 22:35
And then while the female is feeding the male cockroach, smooth as you please, essentially starts scooting his abdomen further and further back underneath the female until he’s close enough so that the phallomere, which is just one of the sort of the accessory parts of the whole genitalic structure, can clasp on to the female genitals, and then once they’re connected, they’re connected.

Tessa 22:59
So what you’re saying is he does… he’s a gentleman, and he does take her out to dinner first.

Charles 23:02
Yes, but in a… he’s less of a gentleman because he’s also kind of pulling the, he’s doing basically a more sexual version of like, sneakily putting your arm around somebody at the movies.

Tessa 23:17
Okay, fair enough.

Charles 23:18
So he’s, he has first distracted her with popcorn, and is now…

Tessa 23:22
I gotcha.

Charles 23:23
Snaking the arm around, but instead of an arm, it’s genitals.

Tessa 23:28
Gotcha.

Charles 23:29
You know.

Tessa 23:30
As one does.

Charles 23:30
Yeah, I started doing a deep dive into insect genitals and genitalic structures and the evolution thereof. And then I was like, I don’t have… I don’t have time for this. And also, I don’t think it’s going to be anybody’s benefit except from exclusively mine. But an interesting thing about a cockroaches is that, like in… as we have discussed at length before, insect genitals are very important for a variety of reasons. One is they enable insects to keep making more of themselves and a world without insects is no world that I want to live on. And it’s also a world that I can’t live on…

Tessa 24:07
Right, because we kind of need them.

Charles 24:08
Life as we know it would become impossible.

Tessa 24:11
Yeah.

Charles 24:11
But also, I really cannot emphasize enough to you and to everybody listening, how much time entomologists, especially insect taxonomists, have spent collectively looking at, documenting, measuring, describing, comparing insect genitals because of a couple of things. Insect genitals are important for taxonomic descriptions because often… like, if you look up descriptions of a lot of insects, it’s like, “you will recognize it because the genitals look like this.” And they have been used a lot in phylogenetic reconstructions, so in trying to figure out the most likely evolutionary relationships between groups, right makes sense on the assumption that genitals are the most resistant to sort of general phenotypic plasticity.

Tessa 25:01
Right.

Charles 25:01
Phenotypic plasticity being like, your phenotype – as in, how you look what your body is like, etcetera, etcetera – changing based on environmental conditions. An example of phenotypic plasticity is like, the same species of frog might be larger in one year where they have a lot of food available…

Tessa 25:19
Right.

Charles 25:20
… the ones that develop to adulthood might end up smaller in leaner times, right? That’s phenotypic plasticity. And the assumption, then, with regards to genitals, is that that’s much less likely because if you change up the genitals too much, then you won’t be able to actually reproduce with the other members of your species. And well, that’s… the ballgame.

Tessa 25:41
There’s sort of a limit on that.

Charles 25:42
And all of this is like, this is one of those questions that has been being bat back and forth by evolutionary biologists for, you know, as long as we’ve had evolutionary biologists basically. So, you know, I don’t want people to come away from this thinking of being really like hardline supporters of lock and key theory. You know, that’s not what I’m supporting. But I’m just saying, I’m trying to emphasize that genitals, just as a fun tangent for me, genitals are really important. I might edit all of that out, but I might leave it in depends on how I’m feeling when I edit this.

Charles 26:14
All that to say is that I started doing a deep dive into genitalic structures and the evolution thereof, and then I was like, I gotta, if I continue this way, I’m not gonna get anything else done. I’m not gonna get anything else done. So that’s all that is to establish that Blattella germanica also has – not the same courtship ritual, but a very specific, well documented series of behaviors leading up to copulation, in the same way that Drosophila melanogaster does. [interstiaial]

Charles 26:47
The inciting incident for this whole episode was I was looking for papers discussing the Blattella germanica behavior, which, you know, I know very well, like I took an insect behavior course for my master’s, and this was one of the things that we talked about, because there was somebody who had Blattella germanica specimens, we were able to get them in class, we watched this happen. So then I found a paper, published in 2011, called “Conservation of fruitless’ role as master regulator of male courtship behaviour from cockroaches to flies.” And I was like, Huh, interesting.

Charles 27:21
And essentially, this paper was written, these researchers wanted to investigate whether and how much the fruitless gene – well-established, well-described in Drosophila melanogaster – will also regulate courtship behavior in another insect, [the] reasoning behind the choice of Blattella germanica. The whole stereotyped courtship sequence of both for Drosophila melanogaster and Blattella germanica, are at this point exhaustively well documented. So if we know that this… if we know about this gene, we’ve described it very well in one species, and we know that it strongly correlates to a really well documented courtship sequence in an also otherwise well studied model organism, how does it work in this other, really well studied model organism with a well documented courtship sequence, right?

Charles 28:06
And part of what they talked about in their sort of introductory issue is that cockroaches are, in the overall insect phylogenetic tree, relatively basal compared to the highly derived drosophila. And essentially to describe this without getting annoyingly deep into it…

Automated Robot Voice 28:21
Long insect phylogeny interlude ends in about five minutes.

Charles 28:24
When we talk about basal groups inside of a phylogeny. Just to establish – a phylogeny is like… if you’ve ever seen a tree of life diagram, that’s a phylogeny. It’s essentially a representation of the branching pattern of lineages through time to reconstruct how different groups of organisms have evolved and how they’re related to each other in evolutionary terms. Right?

Tessa 28:50
Right.

Charles 28:51
When we talk about derived and basal, we’re talking about the relative position of groups that we’re interested in relative to sort of the original ancestor that we’re identifying. So for insects, there was at some point an insectoid ancestor from which all insects have descended, right. And so essentially, the story of insect phylogeny, as it is sort of broadly accepted at this point, is that the first point of divergence, right, led to the apterygotes, or the wingless insects, so before the evolution of wings, and then all the other insects, and then that group of insects that led to the dragonflies and damselflies (the Odonata) and mayflies (Ephemeroptera). These used to be grouped together as Paleoptera – or like old wings, right, paleo, ptera. I have a vague memory of reading a paper that was like, we shouldn’t be grouping these two together after all, but those are basically… those are the first lineages that evolved after the evolution of wings. And then after that, we got this big clade known as Polyneoptera. And I realized that the specific taxonomic names of these groups probably are not relevant or interesting to almost anybody, but my background is in insect systematics. So if I didn’t, like, say “oh the Polyneoptera,” it’s like, what did I even do a masters for?

Tessa 30:22
Look, our listeners knew what they were getting into when they tuned in.

Charles 30:25
They knew what they were getting into. This is the podcast. And so Polyneoptera includes a lot of very familiar groups, most particularly Orthoptera, which are grasshoppers, crickets, katydids, etc. And then a bunch of other orders, a lot of which have historically been placed in Orthoptera. So like a lot of like, at one point, people thought that mantises were just weird grasshoppers. And really why that’s important is that includes my darling group, Dictyoptera, which includes mantises, termites and cockroaches, as we were discussing before, and inevitably will again.

Charles 30:57
And so as another extremely niche nerd note, some people might come from me saying cockroaches, termites and mantises on the basis that phylogenetically speaking, it is now understood that termites are highly specialized cockroaches. But my opinion is that, especially or at least in relatively colloquial or informal speech, when we’re talking about visually and ecologically cohesive groups – phylogenetically speaking, cockroaches might include the termites, but I think that cockroach as a functional unit, separate from termites, is still a useful framework… colon, a dissertation by Charles Wallace.

Charles 31:42
It’s like, here’s a, here’s an actual good analogy that I’m going to use. It’s like when people will be like, is a tomato a fruit or vegetable, and then people will be like, Aha, it is a fruit because botanically speaking, it is a fruit because it has seeds. But culinarily speaking, it’s a vegetable, right? And my thing is, we can’t start calling tomatoes a fruit, and getting mad at people for saying that tomato is not a fruit, unless we’re willing to be complete about it. And like a cucumbers a fruit, pumpkin is a fruit.

Tessa 32:14
Right, right, right.

Charles 32:15
Botanically speaking vegetables don’t exist – botanically. But if I’m in the kitchen, you know, preparing a pasta sauce, botanical classification doesn’t matter to me, I’m thinking culinary categories. And in that category, I am going to make a pasta sauce out of tomatoes, I’m not going to make a pasta sauce out of strawberries, even though they’re both red fruits. In that sense, at least, if we’re thinking about phylogenetically termites are highly specialized cockroaches. But in the culinary realm of, like, talking about ecologically cohesive groups, termites are very dissimilar from cockroaches. And that’s what I’m saying. That’s what I’m saying to you all, colon, a dissertation by Charles Wallace. Anyway.

Automated Robot Voice 33:01
Long insect phylogeny interlude is now over.

Charles 33:03
I’m not going to get deep into the methodology of this paper, because frankly, it’s it’s highly technical. It’s a technical, it’s a technical paper, right. So I’m not going to get deeply into the methodology because I think it would be kind of boring to listen to, and also secretly, you know, I don’t feel confident enough in very specific technical genetic stuff not to trip over myself. But in essence, they cloned and sequenced RNA from different parts of the cockroach bodies, looking at the transcripts of the fruitless gene. And then they did a knockdown where that’s, you know, genetic manipulation, where they prevent, you know, the expression of a gene. In this case, they did a knockdown to stop the expression of the fruitless gene, just meaning that… it’s like turning the off switch on that gene, right.

Charles 33:45
So they first observed unchanged cockroach males with two theoretically sexually interesting female cockroaches. And then they did this genetic manipulation on separate cockroaches, and they put those male cockroaches in with, again, theoretically sexually interesting female cockroaches, and observed whether they performed any of the typical courtship behaviors. And what they found is that the males without the typical fruitless expression didn’t demonstrate the typical wing raising behavior, and none of the females who were put in with them were later observed with sperm in their spermathecae, which are… essentially, a spermatheca is basically just a little sperm reservoir. So like when you mate but maybe you don’t want to fertilize your eggs yet, you can put the sperm, you can store it inside your spermatheca. Not you as in the listener, because you’re probably a human, and we don’t have that.

Tessa 34:39
Right.

Charles 34:39
But if you were a cockroach, you would. And so the paper authors concluded that there was strong evidence that the fruitless gene is implicated in the courtship behavior of both cockroaches and flies, despite the fact that the lineage that eventually led to modern cockroaches branched off way earlier in the evolution of insects then and fruit flies, essentially, they found first that the fruitless gene, even though the specific behaviors were very different in Drosophila melanogaster and Blattella germanica, that specific gene, the expression of that gene did still contribute to following through on courtship behavior… where like, the the absence of sperm in the females is taken as evidence that there were no successful matings that went on between them, right, like there was no transfer of sperm because there was no courtship. And so they found that that gene, even though you know, cockroaches and Drosophila melanogaster are separated by a large amount of evolutionary space and time, that gene was implicated in courtship behaviors in both of them. And from that, they concluded that the fruitless gene is probably extremely well conserved, as in it has been present and stayed largely the same in terms of, you know, its function and the organisms that have it, for an extremely long time, because for it to be present in both cockroaches and Drosophila melanogaster, it would have had to have been present in a very old ancestor in the total lineage of insects.

Tessa 36:17
Very deep in the family tree.

Charles 36:20
Very deep in the family tree. And so in conclusion, interesting. And also, in conclusion, you would not like to live in a world that didn’t have cockroaches in it. And I also would not like to live in that world.

Tessa 36:32
Yeah, we’d have a lot of serious problems.

Charles 36:34
We’re gonna have all kinds of problems. Like I know, if you think that they’re gross. Listen, I’m number one cockroach fan. Cockroaches are my best friend. Sorry to my actual best friend. I don’t mean it. It’s a joke. But I, you know, I’ve been jumpe-scared by a cockroach before, where you turn around and you see one on your floor, and you’re like, how did you get here? And the answer is, our doors aren’t actually 100% well sealed and we live in Arizona where it’s warm all the time.

Tessa 37:01
Right.

Charles 37:02
You know, like, I get it. I understand. I was one of you. I used to hate cockroaches. But then I opened my heart and I understood that they’re also part of God’s glorious creation. Or if you’re an atheist, they’re a part of the secular miracle that is life on Earth. Imagine how unlikely this all is! Unbelievable. They’re just little guys. And they deserve to be alive as…

Tessa 37:26
They’re doing their best.

Charles 37:27
[with emotion] They’re doing their best! Plus some of them are so cute, and so beautiful. And listen, you might think that Blattella germanica is just a humble little roach. It’s not very big. It’s not very flashy, but it’s alive. And it’s doing its best. Anyway, if you want to see the Blattella germanica courtship, I did find a video on YouTube… a lot of negative comments – unbelievable.

Tessa 37:54
Philistines, man. Philistines.

Charles 37:55
Bnbelievable. But that will be in the show notes as well as all of the sources that I’ve used for this episode, which is a fair few. [interstitial]

Charles 38:08
Yeah, well, happy belated Valentine’s Day… don’t sneakily clasp your genitals with anybody else’s, be very upfront about it. That’s my real lesson.

Tessa 38:19
Yes, yes. We at ASAB pod are very big fans of consent.

Charles 38:25
We love cockroaches, but we don’t endorse their methods of initiating copulation. Well, for humans anyway – for cockroaches, you know, it’s none of my business. Okay. Well, Tessa, where can the people find you?

Tessa 38:39
As long as the website continues to last I am on Twitter at @spacermase and also on my website at tessafisher.com.

Charles 38:49
The podcast is on Twitter, as long as it’s around, @ASABpod, or at our website where we post show notes and transcripts for every episode, asabpodcast.com. Our music is by friend of the show and former guests, Nicole Petkovich. We have an interest form if you would like to be a guest on the show that you can find by going to our website or you can email us at ASABpod@gmail.com And if you liked the show, please tell other people about it. That’s… word of mouth is pretty much the number one way that podcasts grow.

Tessa 39:24
And until next time, keep on science-ing.

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