0:23

Charles: Hello and welcome to assigned scientist at bachelors.

0:26

I'm Charles and I'm an entomologist. Tessa: And I'm Tessa and I'm an astrobiologist.

0:30

Charles: And today it's just the two of us for an episode that

0:33

was going to be a Valentine's Day episode but then I

0:37

procrastinated doing research and Tessa forgot that we were

0:41

recording. Tessa: Yeah, pretty much. Charles: But now it's just...

0:44

Tessa: I mean, close enough. Charles: Close enough, days are fake. So I started doing

0:49

research for a Valentine's Day episode thinking, and my initial

0:53

thought was, let's do more weird bugs acts, because that's always

0:57

a crowd pleaser. But then I thought - Valentine's Day is

1:01

not, you know, a Dionysian celebration of excess, it's a

1:06

day for romance. So then I thought all look into mating

1:12

rituals, like courtship rituals, of different insects. And the

1:16

first thing that I thought of was this very well described

1:21

courtship behavior in the species Blattella germanica, or

1:26

the German cockroach. But while I was researching that, I found a paper addressing

1:33

sort of genetic determinations of sexual differentiation in

1:37

insects, genetic control of behavior, and also how well

1:45

established in the insect family tree these genetic controls of

1:49

behavior are. And that is what I will be telling you about today.

1:53

Specifically, the fruitless gene, originally described in

1:58

Drosophila melanogaster, and then later manipulated in

2:03

Blattella germanica. So basically, the fruitless gene was identified in Drosophila

2:09

melanogaster, because as we've talked about before, Drosophila

2:12

melanogaster is like THE model organism for genetics, right?

2:17

Tessa: Yep. Charles: They're commonly known as quote unquote, fruit flies.

2:21

Those in the know might actually call them vinegar flies, but if

2:24

you're actually in the know enough to call them vinegar

2:27

flies, you're probably just going to call them Drosophilidae

2:30

anyway, because you're an entomologist. And I always have

2:33

to bring this up because my master's work was on the fly

2:37

family Ulidiidae, which is in the superfamily Tephritoidea,

2:41

named for the family Tephritidae. And those are the

2:45

fruit flies. And I think, you know, we can get into sort of

2:48

the philosophy and politics of insect common names, but just

2:53

looking at it - fruit flies as in Drosophila as in

2:58

Drosophilidae are known as fruit flies because they are often

3:01

found when you have like rotting fruit in your kitchen, right?

3:05

Because they, like many other flies, lay eggs in rotting

3:09

substrates - like dead stuff, basically, right? This is very,

3:13

very common in flies. It's kind of the defining sort of life

3:17

characteristic of true flies really, where they love to lay

3:21

their eggs in very soft environments where the maggots

3:26

can hatch out of the eggs. And then they're kind of just living

3:30

in a daze of soft, high nutrient sludge until they pupate.

3:37

Tessa: Usually, like in like labs, it's usually like

3:40

potatoes. Charles: Yeah, so you know, that can be fruit, it can be poop, it

3:45

can be bodies, you know, whatever you don't like. Whereas

3:49

Tephritidae is primarily phytophagous, and this is all

3:53

kind of beside the point, but it's - nobody respects true

3:56

flies enough, and I'm gonna change that. And if I can't

3:59

change it, I'm going to make everybody listen to me talk

4:01

about it. Anyway. But essentially, primarily

4:06

phytophagous meaning that they don't just colonize dead plants,

4:11

they colonize living ones, baby. So tephritids will actually lay

4:15

their eggs inside living plant tissue. And because of that a

4:19

lot of tephritids are well known, and well hated, pests on

4:25

agricultural crops, right? Tessa: Right. Yeah, I kind of figured that would be the

4:28

natural result of that. Charles: So my feeling is, tephritids really deserve the

4:34

name of fruit flies, because to drosophilids, they could be

4:39

laying their eggs in any old thing. Whereas tephritids are

4:44

laying their eggs specifically in living fruits. Uh, thank you

4:49

for coming to my TED Talk. But actually as an as another point

4:53

- tephritoids are interesting because most flies, they just

4:56

all have lost the true ovipositor but tephritoids have

5:00

re-evolved an extension of their abdomen to serve as an

5:05

ovipositor. So it is not the same string, it is not like the

5:09

same physical structure that exists ancestrally that...

5:12

Tessa: Right, it's a different one that's been repurposed.

5:14

Charles: Yeah, it is basically, like - we have as humans lost

5:18

our tails. But it's like, what if we evolved, so that just an

5:23

extension of our butt looked like a tail? And that's what

5:27

tephritoids have basically done. Anyway, so the fruitless gene

5:31

was identified Drosophila because - uh, not because it's

5:34

unique to Drosophila, but just because Drosophila, specifically

5:37

Drosophila melanogaster, is the species that everybody was doing

5:40

all of this genetics work on. I was actually, I was doing

5:43

research for this episode, and I was looking at it, and I was

5:45

like, man, a bunch of these early papers identifying

5:50

specific genes in Drosophila are from the 90s. And then I was

5:54

like, Yeah, ya nerd, because that's right after we developed

5:57

PCR. Tessa: Right, right. That's when everybody was sequencing like

6:00

mad. Charles: That's, of course, that's what it was, because

6:03

that's when everybody could do it. Yeah, so the fruitless gene,

6:06

in, identified in Drosophila melanogaster, is known to

6:09

control courtship rituals. So Drosophila melanogaster of...

6:13

males have this whole sequence of behaviors that they will do

6:17

to initiate copulation with females of their species. And

6:20

according to the description on the GeneBrief, on the website of

6:25

the Society of Developmental Biology, quote, "fru encodes a

6:28

set of putative transcription factors that promote male sexual

6:32

behavior by controlling the development of sexually

6:34

dimorphic neuronal circuitry." In other words, transcription

6:37

factors being proteins which control the transcription part

6:41

of the central dogma of molecular biology. So, the

6:44

central dogma being - DNA is just transcribed into RNA. And

6:48

then RNA is translated into proteins. And that is how gene

6:51

expression works. Tessa: Right. Charles: You know, varying parts of that process leads to

6:57

different gene expression. And so fruitless, along with other

7:01

genes, like sex lethal and double sex, are part of this

7:06

cascade controlling sexual differentiation in Drosophila.

7:09

Where - insects do also use... so like humans, as we're all

7:15

taught, use chromosomal sex determination, right? Where,

7:20

obviously very simplified, but if you are XX then you're

7:23

female; if you're XY than you're male. [Deliberately mumbles]

7:26

Simplified, simplified, simplified - so this is trans podcast, whatever, right?

7:29

Tessa: Yeah, yeah, that's a whole other episode. Charles: It's a whole other episode - that, which we did an

7:32

episode about. Tessa: Yeah. Charles: Which I will link but the, the way that that works,

7:36

really, is that during embryological development, the

7:39

SRY gene from the Y chromosome, essentially is like you're gonna

7:43

do this, or you're gonna do this. And then the sort of

7:47

series of sexual changes related to sexual differentiation happen

7:53

because of the production of estrogens or androgens, right,

7:58

where like, if you have testosterone, then this will

8:00

happen - if you have more estrogen than this will happen,

8:03

et cetera, et cetera, et cetera. But that is not how it works in insects, where insects do have a

8:08

chromosomal component... different groups of insects have

8:12

different methods of sex determination, because I mean,

8:15

it's a huge group of animals, right. But in humans, you know,

8:19

we have, we have this one gene, which then leads to whatever and

8:22

then a lot of the actual sexual differentiation during

8:25

development is controlled by hormones, whereas in insects,

8:29

and specifically in Drosophila, specifically, specifically with

8:32

Drosophila melanogaster, it is not that this one gene leads to

8:37

the production of specific hormones, which then control

8:41

further differentiation, it is that specific genes related to,

8:47

you know, the chromosomal method of sexual determination lead to

8:51

these alternative splicings of different genes, which do or do

8:56

not produce functional proteins and putting that in, hopefully,

9:01

a more accessible way... When... earlier I mentioned the central dogma of molecular

9:06

biology, right, where DNA is transcribed to RNA, and RNA is

9:10

translated to proteins, which are basically just... meaning

9:13

DNA is what we think of as your genetic code. That is what you

9:17

have inherited from your parents, that's kind of the

9:19

like, the blueprints of whatever. And then to make those

9:24

blueprints into the house that is your body, uh, first...

9:30

[pause] you know, that's a metaphor that really stalls out

9:33

because there's kind of no intermediate step between

9:35

blueprints and building in the way that there is between DNA

9:39

and proteins. But basically, you have DNA and then the DNA gets

9:44

transcribed into RNA, which is just another form of nucleic

9:50

acids, right? And so RNA then is used to translate into proteins

9:58

where like going down reading the RNA, we have these three

10:01

base pairs, and then you get these whole big structures of

10:06

proteins based on all of the different amino acids and how

10:11

they're connected to each other, and the order in which they're

10:13

translated. And then the idea here with alternative splicing is that

10:17

males and females have like the same whole gene fruitless, but

10:23

because of whether they have been determined to be male or

10:28

female earlier on in development, other genes, double

10:31

sex and sex lethal, again, which sounds so metal... the way that

10:36

those genes have been transcribed and then translated

10:39

results in functional proteins, which then control how fruitless

10:45

goes through that whole process from DNA to proteins. Where in

10:49

males, it will go this one route, and then in females, it

10:53

will go this other route, but it's not because they had they

10:56

had like different copies of the same gene, it is because earlier

11:01

in the process of like sexual differentiation, other genes

11:04

have been spliced, and other proteins have been made, such

11:08

that that kind of keeps the male or female developmental pathway

11:12

rolling forward. Hopefully that makes sense.

11:15

Tessa: Yeah, that makes sense. Charles: Genetics, you know what I mean? Essentially, in the 90s

11:20

people discovered, first of all, they discovered fruitless as a

11:24

gene, and then they were figuring out what it did, they

11:26

do what all those wacky geneticists are always doing,

11:30

which is they created and then mated and experimented on

11:35

etcetera, etcetera, mutants, and so they found, quote, "When fru

11:40

mutant males are grouped together, they form male male

11:43

courtship chains in which each male is simultaneously both

11:46

courting and being courted. All mutant combinations show some

11:50

male male chaining." Tessa: Interesting... the geneticists are making the

11:54

frickin fruit flies gay. Charles: Alex Jones was so upset about the frogs, he was looking

11:59

in the wrong place. And so because of research done on

12:03

fruitless, and mutations thereof, it has come up

12:05

repeatedly as an important piece of evidence in discussions over

12:09

to what degree complex behavior is learned versus genetic, given

12:14

that there is apparently a very straightforward relationship

12:18

between the fruitless gene and courtship behavior, including

12:21

abnormalities in some aspects of courtship, using appendages that

12:25

are otherwise unaffected. So for example, part of the stereotyped

12:30

courtship behavior of Drosophila melanogaster males towards

12:34

females are a wing display described in one paper as quote,

12:38

"singing a species specific courtship song by extending one

12:41

of his wings and vibrating it." And so they, the mutants, the

12:45

fruitless mutants fail at doing this aspect, but it's not a

12:50

mechanical or a physiological problem with their wings,

12:53

because their general ability to fly and other uses of wings are

12:57

not affected. It is specifically the failure to perform that

13:02

courtship behavior. Tessa: I mean, are we sure that this is like because they're

13:06

male-male, or is it just because they've got no game?

13:08

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

13:10

Charles: Yeah, yeah, yeah - where like, yeah, there are

13:10

Tessa: Okay, gotcha. different aspects, I think that are. And this is deeper into the

13:15

sort of the genetics literature than I felt it was responsible

13:19

to go given that I have a bunch of other stuff that I need to be

13:22

doing. But it seems like different specific mutations

13:25

result in a variety of ways that males can fail. So it's not just

13:30

turning the frickin bugs gay, it's also like inability to

13:34

initiate courtship behaviors or inability to complete the whole

13:37

stereotyped sequence. And then also, interestingly, in 2005, several researchers

13:42

completed quote, "gene targeting by homologous recombination to

13:46

generate alleles of fru that are constitutively spliced in either

13:49

the male or female mode," just meaning that they like, took

13:52

flies, and they did some genetics trickery, right? So

13:58

that otherwise quote unquote, normal females would have the

14:02

males splicing pattern or fruitless and otherwise quote,

14:05

unquote normal males would have the female pattern. And they

14:08

found that in the quote unquote, normal females splicing in the

14:11

male pattern resulted in those flies demonstrating typical

14:14

courtship behavior towards other females and males spliced in the

14:18

female pattern, the loss of courtship behavior, and, quote,

14:22

orientation, meaning that they then were doing courtship

14:26

towards males rather than females.

14:28

So that's kind of a general introduction to the fruitless

14:32

gene. And just the idea that there is this gene that is very

14:35

well documented, very well understood, lots of research

14:38

about it in Drosophila melanogaster, which is known and

14:42

has been demonstrated to control the specific stereotype

14:47

courtship behavior. [interstitial] So then, taking a step sideways briefly, I would love to discuss

14:56

Blattella germanica, also known as the German cockroach. I would

15:00

ask if you have seen one of these cockroaches before, but

15:03

the answer is almost certainly that you have.

15:06

Tessa: Oh, yeah, yep. Charles: But you may, you probably didn't recognize it as

15:10

the quote unquote, German cockroach when you did.

15:14

Tessa: Potentially, I don't know how many other varieties that

15:16

are here in Phoenix. Charles: Uh, a variety. So Blattella germanica belongs to

15:21

the extreme, extreme - I'll say it again - extreme minority of

15:26

cockroach specie which are established as quote unquote

15:30

pests, where there are over 4000 described species of

15:33

Tessa: They're getting a bad rap, man.

15:34

cockroaches, not even including termites, which is another

15:38

episode for another day, but over 4000 species, and only like

15:43

30 of them are really well established as, quote, unquote,

15:47

pests in human homes. And yet, all anybody ever wants to talk about.

15:54

Charles: It's unbelievable, especially because here's,

15:57

here's my little bugaboo. It is very, very, very, very, very,

16:01

very, very, extremely common to see cockroaches brought up as a

16:06

health concern, because of their ability to mechanically transmit

16:11

pathogens - mechanically not being, you know, they're getting

16:14

in a forklift and transferring... but

16:17

mechanically, as in pathogens get on them, they get on other

16:20

stuff, the pathogens get on the other stuff, right. But a lot of

16:23

times when people bring this up, they either don't justify it at

16:27

all, or, they appeal to like very controlled experimental

16:32

settings in which it is demonstrated that they can do

16:37

this. But I the evidence that cockroaches are demonstrably a

16:45

significant source of pathogen transmission through them

16:51

walking through pathogen somewhere, and then walking

16:53

through another area and getting them somewhere, and then that

16:56

being a significant source of health problems... I'm gonna say

17:01

it - if you've got it, send it to me, because I haven't seen

17:04

it. And I will say it's, you know, not to minimize cockroaches as a

17:08

potential health concern, because particularly if you have

17:11

large aggregations, cockroaches do produce allergens, which can

17:16

upset anybody but are especially a problem if you have some kind

17:19

of respiratory condition, for example, if you're asthmatic,

17:22

but! Like, in my previous apartment, I was living on the

17:26

ground floor and I had two doors, right. So sometimes I

17:29

would find a random cockroach in my apartment, inevitably. But I

17:34

didn't freak out about it. First of all, because I'm the number

17:36

one friend of cockroaches and they know -

17:39

Tessa: Right, right Charles: - that I love them. And then also because a singular

17:43

cockroach coming into your house from outdoors, even a couple of

17:46

cockroaches that you just see sometimes, you don't need to

17:50

worry about it. Tessa: Yeah, yeah, it's only like, again, there's like

17:52

massive aggregations of them. Charles: Massive aggregations are a problem, but if you have

17:57

the conditions for massive aggregations of cockroaches, you

18:00

have underlying issues...

18:02

Tessa: I was about to say, you've probably got other bigger

18:04

problems to worry about first. Charles: Where it is a part of the problem that you're facing,

18:09

but it is not the only problem. Tessa: Yeah.

18:11

Charles: Like if you just see a cockroach sometimes in your

18:14

house. Tessa: Right. Charles: Respectfully... Tessa: That's not going to do it, yeah.

18:16

Charles: Get over yourself. So back to Blattella germanica

18:20

specifically, it is one of the sort of the classic pest species

18:25

and it has a basically a distribution all over the world,

18:28

but pretty much exclusively in close association with humans.

18:31

And they are small, relatively delicate looking yellow-brown

18:35

roaches that are recognizable because they have these two

18:38

large distinctive dark stripes on their pronotum. In Blattella

18:42

germanica, it's one of those species that carries ootheca, or

18:45

egg case, around hanging at the back of the abdomen, which is

18:49

just always very funny. Because it's like... imagine if - today

18:53

is just a day of horrifying anatomical analogies - but like

18:56

imagine if instead of just giving birth, humans had the

19:01

whole amniotic sac just hanging out of the vagina for a while.

19:07

Right? And then when the baby was finally done, it just kind

19:11

of burst forth. That's kind of that reproductive adaptation in

19:15

all of these cockroaches that have ootheca just hanging...

19:19

their abdomen is just partially open for a while. And as we've

19:23

said, we've discussed before the ootheca in cockroaches typically

19:27

looks like a cute little leather clutch purse, and much like a

19:30

clutch purse, it kind of opens at one side and all the treasure

19:34

comes out. And by treasure I mean a bunch of little

19:37

cockroaches, little immature cockroaches will emerge when the

19:41

egg portion of their life is over. Much like, but not on quite the same level of Drosophila

19:46

melanogaster, Blattella germanica is a very well

19:49

established model organism and there's a huge amount of

19:53

research on Blattella germanica, partially because it is

19:56

financially and culturally important as a quote unquote

19:59

pest species, but also I think part of why there are so many

20:03

studies on Drosophila melanogaster is that there are

20:06

already so many studies on Drosophila.. like if you want to

20:10

dig deep into the genome of an organism, are you going to

20:12

choose an organism that nobody has sequenced before, or are you

20:15

going to choose an organism that already has hundreds of papers

20:18

published on its genes?

20:21

Tessa: Right, right. Charles: If you already know a lot about an organism, it's

20:24

easier to narrowly identify specific, interesting biological

20:29

questions, because there's all of this general information

20:33

that's already kind of taken care of. Tessa: Right, you don't have to, like reinvent the wheel.

20:36

Charles: Right, exactly. And interestingly, Blattella

20:39

germanica, also like Drosophila melanogaster, has a very well

20:42

established, well documented courtship ritual between the

20:47

males and the females to initiate copulation, which was

20:50

actually initially described like 100 years ago. People have

20:53

known how Blattella germanica gets down for longer than almost

20:58

any, any living person, right. And so a description from one

21:03

paper quote, "in an encounter the male touches the female with

21:06

the antennae, raises the wings upward and then turns around 180

21:10

degrees, thus exposing the tergal gland to the female. The

21:13

secretion of these glands stimulates the female to mount

21:15

the male and feed and while the female feeds on the tergal

21:18

gland, the male pushes the abdomen under the female and

21:21

clasps her genitalia with his left phallomere to accomplish

21:24

genital connection." Putting that in, it may be more

21:27

accessible language, essentially, you start out with

21:29

two cockroaches. One of them is... he was a boy, she was a

21:32

girl... Tessa: Can you make it more obvious? Charles: You know, exactly. What the male will do is establish,

21:37

using the antennae, that he's dealing with a female cockroach,

21:41

because Blattella germanica, unlike fruitless mutants,

21:44

definitively said No homo. And so the male establishes that

21:50

it's a female, and then raises his wings up and exposes the

21:54

upper part of his abdomen. And the tergal gland - basically, a

21:57

tergite is just what we call one of those segments of the

22:00

abdomen. And so the tergal gland is just on one of those

22:05

segments. And I did, I did, I spent time looking up the actual

22:10

contents of the secretion of the tergal gland. And I found it

22:14

described in one paper as a combination of quote

22:17

"oligosaccharides, lipids and proteins," which basically just

22:20

means - I dunno, nutrients. You know, where saccharidess -

22:23

sugars; lipids - fats, proteins... protein. And the

22:26

female is like, well, I'm an insect, and therefore always

22:30

under pressure to find sufficient food to keep my life

22:33

continuing. I'm gonna eat this, Tessa: Right.

22:35

Charles: And then while the female is feeding the male

22:38

cockroach, smooth as you please, essentially starts scooting his

22:42

abdomen further and further back underneath the female until he's

22:47

close enough so that the phallomere, which is just one of

22:50

the sort of the accessory parts of the whole genitalic

22:53

structure, can clasp on to the female genitals, and then once

22:57

they're connected, they're connected. Tessa: So what you're saying is he does... he's a gentleman, and

23:01

he does take her out to dinner first. Charles: Yes, but in a... he's less of a gentleman because he's

23:07

also kind of pulling the, he's doing basically a more sexual

23:12

version of like, sneakily putting your arm around somebody

23:16

at the movies. Tessa: Okay, fair enough. Charles: So he's, he has first distracted her with popcorn, and

23:21

is now... Tessa: I gotcha. Charles: Snaking the arm around, but instead of an arm, it's

23:27

genitals. Tessa: Gotcha. Charles: You know.

23:30

Tessa: As one does. Charles: Yeah, I started doing a deep dive into insect genitals

23:36

and genitalic structures and the evolution thereof. And then I

23:39

was like, I don't have... I don't have time for this. And

23:42

also, I don't think it's going to be anybody's benefit except

23:45

from exclusively mine. But an interesting thing about a

23:49

cockroaches is that, like in... as we have discussed at length

23:53

before, insect genitals are very important for a variety of

23:57

reasons. One is they enable insects to keep making more of

24:00

themselves and a world without insects is no world that I want

24:03

to live on. And it's also a world that I can't live on...

24:07

Tessa: Right, because we kind of need them. Charles: Life as we know it would become impossible.

24:11

Tessa: Yeah. Charles: But also, I really cannot emphasize enough to you

24:14

and to everybody listening, how much time entomologists,

24:19

especially insect taxonomists, have spent collectively looking

24:23

at, documenting, measuring, describing, comparing insect

24:28

genitals because of a couple of things. Insect genitals are

24:32

important for taxonomic descriptions because often...

24:35

like, if you look up descriptions of a lot of

24:38

insects, it's like, "you will recognize it because the

24:41

genitals look like this." And they have been used a lot in

24:45

phylogenetic reconstructions, so in trying to figure out the most

24:49

likely evolutionary relationships between groups,

24:52

right makes sense on the assumption that genitals are the

24:56

most resistant to sort of general phenotypic plasticity.

25:01

Tessa: Right. Charles: Phenotypic plasticity being like, your phenotype - as

25:04

in, how you look what your body is like, etcetera, etcetera -

25:08

changing based on environmental conditions. An example of

25:11

phenotypic plasticity is like, the same species of frog might

25:15

be larger in one year where they have a lot of food available...

25:19

Tessa: Right. Charles: ... the ones that develop to adulthood might end

25:22

up smaller in leaner times, right? That's phenotypic

25:24

plasticity. And the assumption, then, with regards to genitals,

25:28

is that that's much less likely because if you change up the

25:32

genitals too much, then you won't be able to actually

25:36

reproduce with the other members of your species. And well,

25:39

that's... the ballgame. Tessa: There's sort of a limit on that.

25:42

Charles: And all of this is like, this is one of those

25:44

questions that has been being bat back and forth by

25:48

evolutionary biologists for, you know, as long as we've had

25:51

evolutionary biologists basically. So, you know, I don't

25:54

want people to come away from this thinking of being really

25:58

like hardline supporters of lock and key theory. You know, that's

26:01

not what I'm supporting. But I'm just saying, I'm trying to

26:03

emphasize that genitals, just as a fun tangent for me, genitals

26:08

are really important. I might edit all of that out, but I

26:11

might leave it in depends on how I'm feeling when I edit this.

26:14

All that to say is that I started doing a deep dive into

26:17

genitalic structures and the evolution thereof, and then I

26:19

was like, I gotta, if I continue this way, I'm not gonna get

26:22

anything else done. I'm not gonna get anything else done. So

26:25

that's all that is to establish that Blattella germanica also

26:29

has - not the same courtship ritual, but a very specific,

26:34

well documented series of behaviors leading up to

26:39

copulation, in the same way that Drosophila melanogaster does.

26:42

[interstiaial] The inciting incident for this whole episode was I was looking

26:50

for papers discussing the Blattella germanica behavior,

26:54

which, you know, I know very well, like I took an insect

26:57

behavior course for my master's, and this was one of the things

27:00

that we talked about, because there was somebody who had

27:03

Blattella germanica specimens, we were able to get them in

27:06

class, we watched this happen. So then I found a paper,

27:10

published in 2011, called "Conservation of fruitless' role

27:14

as master regulator of male courtship behaviour from

27:18

cockroaches to flies." And I was like, Huh, interesting.

27:21

And essentially, this paper was written, these researchers

27:25

wanted to investigate whether and how much the fruitless gene

27:29

- well-established, well-described in Drosophila

27:32

melanogaster - will also regulate courtship behavior in

27:35

another insect, [the] reasoning behind the choice of Blattella

27:37

germanica. The whole stereotyped courtship sequence of both for

27:40

Drosophila melanogaster and Blattella germanica, are at this

27:43

point exhaustively well documented. So if we know that

27:47

this... if we know about this gene, we've described it very

27:50

well in one species, and we know that it strongly correlates to a

27:54

really well documented courtship sequence in an also otherwise

27:58

well studied model organism, how does it work in this other,

28:02

really well studied model organism with a well documented

28:04

courtship sequence, right? And part of what they talked about in their sort of

28:08

introductory issue is that cockroaches are, in the overall

28:12

insect phylogenetic tree, relatively basal compared to the

28:16

highly derived drosophila. And essentially to describe this

28:19

without getting annoyingly deep into it... Automated Robot Voice: Long insect phylogeny interlude ends

28:23

in about five minutes. Charles: When we talk about basal groups inside of a

28:27

phylogeny. Just to establish - a phylogeny is like... if you've

28:30

ever seen a tree of life diagram, that's a phylogeny.

28:33

It's essentially a representation of the branching

28:38

pattern of lineages through time to reconstruct how different

28:44

groups of organisms have evolved and how they're related to each

28:48

other in evolutionary terms. Right?

28:50

Tessa: Right. Charles: When we talk about derived and basal, we're talking

28:54

about the relative position of groups that we're interested in

28:58

relative to sort of the original ancestor that we're identifying.

29:04

So for insects, there was at some point an insectoid ancestor

29:10

from which all insects have descended, right. And so

29:15

essentially, the story of insect phylogeny, as it is sort of

29:19

broadly accepted at this point, is that the first point of

29:22

divergence, right, led to the apterygotes, or the wingless

29:27

insects, so before the evolution of wings, and then all the other

29:30

insects, and then that group of insects that led to the

29:35

dragonflies and damselflies (the Odonata) and mayflies

29:39

(Ephemeroptera). These used to be grouped together as

29:43

Paleoptera - or like old wings, right, paleo, ptera. I have a

29:47

vague memory of reading a paper that was like, we shouldn't be

29:50

grouping these two together after all, but those are

29:53

basically... those are the first lineages that evolved after the

29:57

evolution of wings. And then after that, we got this big

30:01

clade known as Polyneoptera. And I realized that the specific

30:05

taxonomic names of these groups probably are not relevant or

30:09

interesting to almost anybody, but my background is in insect

30:15

systematics. So if I didn't, like, say "oh the Polyneoptera,"

30:20

it's like, what did I even do a masters for?

30:22

Tessa: Look, our listeners knew what they were getting into when

30:24

they tuned in. Charles: They knew what they were getting into. This is the

30:27

podcast. And so Polyneoptera includes a lot of very familiar

30:32

groups, most particularly Orthoptera, which are

30:35

grasshoppers, crickets, katydids, etc. And then a bunch

30:38

of other orders, a lot of which have historically been placed in

30:41

Orthoptera. So like a lot of like, at one point, people

30:44

thought that mantises were just weird grasshoppers. And really

30:48

why that's important is that includes my darling group,

30:51

Dictyoptera, which includes mantises, termites and

30:54

cockroaches, as we were discussing before, and

30:56

inevitably will again. And so as another extremely niche nerd note, some people

31:02

might come from me saying cockroaches, termites and

31:05

mantises on the basis that phylogenetically speaking, it is

31:09

now understood that termites are highly specialized cockroaches.

31:14

But my opinion is that, especially or at least in

31:19

relatively colloquial or informal speech, when we're

31:22

talking about visually and ecologically cohesive groups -

31:26

phylogenetically speaking, cockroaches might include the

31:31

termites, but I think that cockroach as a functional unit,

31:35

separate from termites, is still a useful framework... colon, a

31:40

dissertation by Charles Wallace. It's like, here's a, here's an actual good analogy that I'm

31:46

going to use. It's like when people will be like, is a tomato

31:50

a fruit or vegetable, and then people will be like, Aha, it is

31:53

a fruit because botanically speaking, it is a fruit because

31:56

it has seeds. But culinarily speaking, it's a vegetable,

32:00

right? And my thing is, we can't start calling tomatoes a fruit,

32:04

and getting mad at people for saying that tomato is not a

32:07

fruit, unless we're willing to be complete about it. And like a

32:11

cucumbers a fruit, pumpkin is a fruit.

32:14

Tessa: Right, right, right. Charles: Botanically speaking vegetables don't exist -

32:18

botanically. But if I'm in the kitchen, you know, preparing a

32:22

pasta sauce, botanical classification doesn't matter to

32:25

me, I'm thinking culinary categories. And in that

32:29

category, I am going to make a pasta sauce out of tomatoes, I'm

32:32

not going to make a pasta sauce out of strawberries, even though

32:35

they're both red fruits. In that sense, at least, if we're

32:38

thinking about phylogenetically termites are highly specialized

32:42

cockroaches. But in the culinary realm of, like, talking about

32:47

ecologically cohesive groups, termites are very dissimilar

32:53

from cockroaches. And that's what I'm saying. That's what I'm

32:56

saying to you all, colon, a dissertation by Charles Wallace.

33:00

Anyway. Automated Robot Voice: Long insect phylogeny interlude is

33:03

now over. Charles: I'm not going to get deep into the methodology of

33:05

this paper, because frankly, it's it's highly technical. It's

33:10

a technical, it's a technical paper, right. So I'm not going

33:12

to get deeply into the methodology because I think it would be kind of boring to listen to, and also secretly,

33:17

you know, I don't feel confident enough in very specific

33:19

technical genetic stuff not to trip over myself. But in

33:22

essence, they cloned and sequenced RNA from different

33:25

parts of the cockroach bodies, looking at the transcripts of

33:29

the fruitless gene. And then they did a knockdown where

33:32

that's, you know, genetic manipulation, where they

33:35

prevent, you know, the expression of a gene. In this

33:38

case, they did a knockdown to stop the expression of the

33:41

fruitless gene, just meaning that... it's like turning the

33:44

off switch on that gene, right. So they first observed unchanged cockroach males with two

33:51

theoretically sexually interesting female cockroaches.

33:55

And then they did this genetic manipulation on separate

33:58

cockroaches, and they put those male cockroaches in with, again,

34:02

theoretically sexually interesting female cockroaches,

34:06

and observed whether they performed any of the typical

34:08

courtship behaviors. And what they found is that the males

34:11

without the typical fruitless expression didn't demonstrate

34:14

the typical wing raising behavior, and none of the

34:17

females who were put in with them were later observed with

34:20

sperm in their spermathecae, which are... essentially, a

34:25

spermatheca is basically just a little sperm reservoir. So like

34:29

when you mate but maybe you don't want to fertilize your

34:31

eggs yet, you can put the sperm, you can store it inside your

34:34

spermatheca. Not you as in the listener, because you're

34:36

probably a human, and we don't have that.

34:39

Tessa: Right. Charles: But if you were a cockroach, you would. And so the

34:42

paper authors concluded that there was strong evidence that

34:45

the fruitless gene is implicated in the courtship behavior of

34:49

both cockroaches and flies, despite the fact that the

34:52

lineage that eventually led to modern cockroaches branched off

34:57

way earlier in the evolution of insects then and fruit flies,

35:00

essentially, they found first that the fruitless gene, even

35:06

though the specific behaviors were very different in

35:09

Drosophila melanogaster and Blattella germanica, that

35:12

specific gene, the expression of that gene did still contribute

35:16

to following through on courtship behavior... where

35:19

like, the the absence of sperm in the females is taken as

35:22

evidence that there were no successful matings that went on

35:25

between them, right, like there was no transfer of sperm because

35:28

there was no courtship. And so they found that that gene, even

35:32

though you know, cockroaches and Drosophila melanogaster are

35:36

separated by a large amount of evolutionary space and time,

35:41

that gene was implicated in courtship behaviors in both of

35:45

them. And from that, they concluded that the fruitless

35:50

gene is probably extremely well conserved, as in it has been

35:55

present and stayed largely the same in terms of, you know, its

36:00

function and the organisms that have it, for an extremely long

36:04

time, because for it to be present in both cockroaches and

36:09

Drosophila melanogaster, it would have had to have been

36:12

present in a very old ancestor in the total lineage of insects.

36:17

Tessa: Very deep in the family tree.

36:20

Charles: Very deep in the family tree. And so in conclusion,

36:25

interesting. And also, in conclusion, you would not like

36:28

to live in a world that didn't have cockroaches in it. And I

36:31

also would not like to live in that world. Tessa: Yeah, we'd have a lot of serious problems.

36:34

Charles: We're gonna have all kinds of problems. Like I know,

36:37

if you think that they're gross. Listen, I'm number one cockroach

36:41

fan. Cockroaches are my best friend. Sorry to my actual best

36:45

friend. I don't mean it. It's a joke. But I, you know, I've been

36:48

jumpe-scared by a cockroach before, where you turn around

36:51

and you see one on your floor, and you're like, how did you get

36:54

here? And the answer is, our doors aren't actually 100% well

36:58

sealed and we live in Arizona where it's warm all the time.

37:01

Tessa: Right. Charles: You know, like, I get it. I understand. I was one of

37:05

you. I used to hate cockroaches. But then I opened my heart and I

37:10

understood that they're also part of God's glorious creation.

37:13

Or if you're an atheist, they're a part of the secular miracle

37:18

that is life on Earth. Imagine how unlikely this all is!

37:22

Unbelievable. They're just little guys. And they deserve to

37:26

be alive as... Tessa: They're doing their best. Charles: [with emotion] They're doing their best! Plus some of

37:30

them are so cute, and so beautiful. And listen, you might

37:33

think that Blattella germanica is just a humble little roach.

37:37

It's not very big. It's not very flashy, but it's alive. And it's

37:41

doing its best. Anyway, if you want to see the Blattella

37:47

germanica courtship, I did find a video on YouTube... a lot of

37:52

negative comments - unbelievable. Tessa: Philistines, man. Philistines.

37:55

Charles: Bnbelievable. But that will be in the show notes as

37:58

well as all of the sources that I've used for this episode,

38:00

which is a fair few. [interstitial]

38:08

Yeah, well, happy belated Valentine's Day... don't

38:13

sneakily clasp your genitals with anybody else's, be very

38:17

upfront about it. That's my real lesson. Tessa: Yes, yes. We at ASAB pod are very big fans of consent.

38:25

Charles: We love cockroaches, but we don't endorse their

38:29

methods of initiating copulation. Well, for humans

38:32

anyway - for cockroaches, you know, it's none of my business.

38:35

Okay. Well, Tessa, where can the people find you?

38:39

Tessa: As long as the website continues to last I am on

38:43

Twitter at @spacermase and also on my website at

38:47

tessafisher.com. Charles: The podcast is on Twitter, as long as it's around,

39:04

@ASABpod, or at our website where we post show notes and

39:09

transcripts for every episode, asabpodcast.com. Our music is by friend of the show and former guests, Nicole Petkovich. We

39:14

have an interest form if you would like to be a guest on the

39:19

show that you can find by going to our website or you can email us at [email protected] And if you liked the show, please tell

39:21

other people about it. That's... word of mouth is pretty much the number one way that podcasts grow.

39:25

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