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Episode 4: Splitgill mushroom

Hannah teaches Elizabeth and Ilana about fungal basics and then the discovery, appearance, ecology and queerness of the pale-gilled shelf fungus found on decaying wood around the world. Hint: they take biological sexes to the next level and beyond!

For more information, take a look at our sources in the episode transcript on our website.

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Timestamps

Species introduction: 1:05

Overview of fungi: 3:34

Splitgill mushroom ecology: 22:10

Description of the mushroom’s looks: 33:07

Sex and gender in fungi overall: 38:28

Splitgill genderqueerness: 45:05


Ilana (I): Hi everyone, and welcome to today's episode of Queerly Natural, where we talk about queerness in the natural world. We discuss different traits and qualities of animals, plants, fungi, and more and how they relate to queer identities in humans. Some may argue our identities are not natural and we are here to say, they queerly are! We are your hosts. I'm Ilana,

Hannah (H): I'm Hannah,

Elizabeth (E): And I'm Elizabeth.

H: Thank you so much for the support the show has gotten so far on patreon and on social media. If you're interested in supporting the show, subscribing wherever you listen to podcasts and letting people know about us through word of mouth are most appreciated. I'm so excited for you to hear me talk about Schizophyllum commune or the splitgill mushroom it's a charming little organism and I hope you agree by the end of the episode. Have a good time and I'll see you on the other side.


H: Today on Queerly Natural we will be talking about the split gill mushroom also called Schizophyllum commune or Schizophyllum commune depending on how you want to say it.

I: A mouthful.

E: You just pick one and we'll go with it. You are officially the expert on this mushroom go.

I: Say it with confidence as my professors have once said.

E: Yes nobody speaks latin, they can't tell you you're wrong.

I: Well, my brother does but it's fine.

E: Most people don't speak latin right it's fine.

H: It's a dead language.

I: Don't tell him.

E: He probably doesn't mind.

H: Okay so, we'll be talking about I'm going to go with Schizophyllum commune or the splitgill mushroom and Schizophyllum commune is the fungus with over 23 000 sexes.

E: Um what?

I: Wow.

E: Did you just... did you just say 23,000, 23,000!

H: More than.

E: Oh good more than 23 000. Alright,t okay, okay.

I: So imagine everyone at our school being a different gender and then still having a lot more to go.

E: That's wow.

H: Yeah 23,000, that's like a small city.

E: Wow okay alright you know and people can't even grasp that there's more than two in humans. I am very excited for this episode. This is gonna be great.

H: Right imagine if there was twenty three thousand, well the exact number in Schizophyllum commune is 23,328.

E: 23,328 is that what you said.

H: Yeah.

E: Wooooow, wow, wow, wow, wow, wow!

H: That's the total.

E: I really hope that maybe some folks who aren't familiar with the concepts of gender fluidity and other sexes listen to this episode and I just like I wish I could see the expression on their face right now.

I: You have just heard what it sounds like when Elizabeth's mind explodes.

E: Yeah it did. There was a little puff out of my ears. It's gone. It was really cool though, I'm very excited about this explosion. Let's, hit me again, hit me again let's go!

H: Yeah it's so exciting. So, some of our listeners may have heard of this fungus already there was a Discover Magazine article about it a couple years ago. So we thought it might be a more widely known fungus to start with because fungi are not necessarily the most well-known.

E: Okay cool.

H: Which is why I wanted to start off with an overview where we just kind of answer some basic questions about fungi for some of our listeners who maybe don't have quite a strong background in biology or mycology.

E: I appreciate that, as the non-mycologist in this room my fungal knowledge is mostly limited to what you two have taught me in our friendship.

I: It's probably more than most people.

E: Ooh i'm very sure it's more than most people. I at least know they're not plants. I'm on that page.

I: You're better than my grandmother.

H: Yeah same, same. I don't know if my grandmother knows that either.

I: Mine thought they flowered after they mushroomed.

H: Oh no, first thing i'll say is they don't do that. They don't do that. They don't, they don't become flowers.

I:They do not.

E: That's okay she was trying.

H: Right. So, to begin our fungus background I want to start with the question what is a fungus and to answer that I'll say a fungus is an organism in the kingdom fungi. So fungi are not plants or animals, like Ilana said her grandmother thinks they're flowers, they're not. They're not plants so they never flower. And what distinguishes them from plants and animals is, unlike animals fungi have cell walls and animals only have a cell membrane and then unlike plants, fungi don't photosynthesize. So, plants are autotrophic meaning they make their own food from sunlight, they don't take in food from their environment. They take in like water and minerals from the soil but their energy like the sugar they eat they make themselves from sunlight.

E: Right look at them hard little busy bees. I like it.

H: Self-reliant independent plants are.

E: I love it.

H: Well not quite, they rely on a lot of microbes and stuff including fungi.

E: But they feed themselves, which is an improvement over a lot of human beings, including me. I: Technically, we never feed ourselves. We can't photosynthesize.

H: We can't photosynthesize.

E: Well that's true but I was also thinking in terms of people cooking for me and I like can't even cook for myself. So it's an extra level of incompetent here.

I: We'll get you there.

E: Okay.

H: Yeah, we'll get you there. You'll be as close to autotrophic as possible.

E: Love it. That sounds good.

I: I wish we could photosynthesize.

E: Sometimes I feel like I can, just because I don't get enough sun. So when I step out i'm like ‘oh’ but yeah I know no photosynthesis.

H: Right, so since fungi don't photosynthesize they are considered heterotrophic which means that since they can't make their own food they have to get their food from the environment around them like we do. Like we're heterotrophic like Elizabeth said, we have to go to the grocery store to buy the food that we cook, hypothetically if we have the energy to cook.

E: Or call the takeout place for delivery that's, that's another way. But yes we do not produce our own food. So we're also heterotrophs just like fungi.

H: Right but fungi of course cannot go to the grocery store. So instead of doing that fungi are made up of this substance called mycelium and mycelium is basically long filaments or chains of single cells connected end to end.

E: Oh kind of like hair?

H: Yeah since they're only a single cell thick, they look fuzzy like they look kind of white and hairy.

E: Oh okay, I'm picturing a mushroom with a ponytail now, just so you know.

I: Many of you have probably seen mycelium. If you go into the woods or really any outdoor area and maybe you turn over a log or something like that and you see like this white fuzzy stuff underneath you found mycelium!

E: is that the mycelium?

I: Umhm (yes)

E: Hey i've seen that stuff! Okay cool not, not a ponytail. I'm retracting that mental image. Okay cool, fuzzy white stuff.

H: yeah not a ponytail.

I: A lot of it you can't really see well but yeah.

E: Okay so what do they use the mycelium for?

H: Fungi are made up of this mycelium and to get their energy they will secrete digestive enzymes from their mycelium. And these digestive enzymes are actually pretty similar to the acids that we make in our stomach.

E: oh!

E: And they put these enzymes into the environment and break down whatever they're growing on which is called a substrate. So this is often like dead wood or soil.

E: Or plant. I know Ilana talkss about fungi and plants.

H: Or plants right.

I: Yeah. Some fungi instead of degrading will actually form associations with plants to get nutrients.

E: Super cool i bet we'll hear more about that.

I: That'll be another day.

H: Yes. But the ones that break down their substrate and decompose it, they put out these enzymes the substrate is degraded and then they directly absorb the products from around them. So they don't necessarily put anything physical in their body they just kind of absorb the nutrients as they decay off of their substrate.

E: So they spit acidic enzymes into what they're sitting on and it turns into a little bitty puddle of goo and then they slurp it up. Yes?

H: Yeah pretty much.

E: Cool I like it

H: Right, it's pretty badass and like Ilana said not all mushrooms do this. These are only the decomposers that do that.

E: Oh okay, okay. What other kinds of mushrooms are there?

H: There's a whole group of fungi called mycorrhizae that instead of getting their nutrients from breaking down the environment around them they form a mutually beneficial relationship with plants. So their mycelium will like connect to the end of a plant root and then the fungus will take up water and nutrients and give those to the plant and then in exchange the plant will give the fungus sugars that it made in its leaves, so the fungus gets food.

E: That's so cool!

H: Right.

E: Oh my god what a partnership! I love that. That's awesome.

I: It's very cool and a very long conversation too.

E: Yeah. I've like, I've heard about mycorrhizae before but like very briefly. Is this a really common thing in plants?

I: In plants, yeah.

H: Over 90% of plant genera rely on mycorrhizae to survive on land.

E: Oh my god! Wait, wait, wait. 90% of plants have this fungal partner, basically and that's part of how they get their water and nutrients.

I: Yeah.

E: Why don't we hear about these more!?

I: It's believed the fungi are kind of the reason plants were able to make the transition from ocean and water to land.

E: I've taken multiple botany classes and we talked about mycorrhizae for like a day. What the heck.

H: I think it's a lot of bias because like you know the plant is aboveground, it's much easier to see, and it's there every year reliably. And the same cannot be said of mushrooms. Like I said, they're often growing inside of their substrate and then whenever they do produce a mushroom if they produce a mushroom at all, and i'll explain the difference between a fungus and a mushroom in a minute, it's not necessarily reliable like they might make a mushroom once every 20 years or something.

I: They also just like to be confusing, where a lot of them might look very similar but might be different species and like even when we go in with genetics sometimes they're just like but what if I make you even more confusing and so it's gets complicated.

H: So yeah there's a couple reasons plants are a little more well studied, perhaps but that doesn't necessarily mean that plants are more important. As we just said many terrestrial ecosystems that we rely on are like running because the fungi are underground like pulling the strings you know.

I: Thank the fungi in your life, they deserve it.

H: Yes they deserve the credit.

E: Yeah, dang. Talk about invisible mvps, wow!

H: Back to what makes a fungus a fungus and not a plant or an animal. Though both plants and fungi have cell walls, plants are also distinguished from fungi because the cell walls are made of different materials. In plants, the cell wall is composed of cellulose but in fungi, the cell wall is composed of chitin which is the protein that also makes up the exoskeleton of insects.

E: Fungi have cell walls made of chitin! What? That's like a ladybug shell or a scorpion's exoskeleton.

I: A cicada if you live in those areas of the us this year.

E: Yeah, yeah you guys might be hearing a lot of those at the moment. Wow cell walls, okay.

H: And the fact that fungi make chitin and insects make chitin is kind of related to my next point which is that originally scientists considered fungi to be a type of lower plant and we'll also talk about why like lower is not necessarily a good designation lower and higher are wrong because that implies superiority inferiority when that's just not true like everything that is alive has you know survived all the mass extinctions that have happened and are equally adapted to surviving their, you know, current conditions like there's no reason to call them higher or lower.

E: Yeah makes perfect sense.

H: Right. But originally fungi were considered a type of lower plant. However now that more research has been done, we have found out that they are actually more closely related to animals than plants.

E: Ah, that's so cool.

H: Right the reason that that is is because fungi and animals share a relatively recent common ancestor and are both in a group called opistakanta. And this group is defined by all of its members having a cell with a tail at some point in their life cycle and perhaps some of the descendants have lost that cell with a tail but their ancestor at some point had that trait. So like in our life cycle that cell would be our sperm, in most animals it would be their sperm and in fungi that cell with the tail has been lost in most groups but the ketridi mycota have spores with a tail as well.

I: And you might have heard of the kytrids from the recent fungus that is causing a lot of disease and death in frog species.

E: Well relatively recent, the last 40 years.

I: It's recent a science.

H: And if you think about it like they they have a tail because kytrid fungi are found in water environments and their gametes need to swim you know and what do frogs do?

I: Just keep swimming.

H: Love a good swim.

I: Swim, swim.

H: Right.

E: So wait, if kytrids are the main group with the tail left and they have the tail because they're aquatic does that mean most fungi are not aquatic.

H: Yeah so they are in this group because they (scientists) think that the original fungi ancestor, so the original fungus that gave rise to all of the fungi that now exist today, that original fungus had the tail. So their ancestor had the tail but as fungi moved to drier environments they relied on different things to disperse their spores other than water so they didn't really necessarily need the tail to swim anymore and most fungi now rely on air to disperse their spores.

E: Okay so most fungi are land-based today.

H: Well as far as we know. Like there are marine fungi and they're very understudied so like maybe they're more diverse.

I: Fungi in general are understudied. So when an understudied whole kingdom says that they have a specific group that's understudied, it's very understudied.

H: And just to give listeners an idea of just how understudied fungi are, scientists estimate that for every one species of plant that exists there are six species of fungi that exist. So there are six times as many fungi species as plant species, however right now the number of described plant species far outnumbers the described fungi species. There are about 391,000 species of vascular plants currently known to science but that's vascular plants so there's more than 391,000 described plants but there are only a total of 97,000 species of described fungi.

E: Okay, yeah that's definitely an off ratio. There's six times as many fungus as plants and we have identified four times as many plants as fungus that means there's 24 species of fungus left to be discovered for every species of plant just say y’all.

H: Exactly.

I: Fungi are just so cool, everyone's intimidated to learn about them.

E: I mean fair.

H: Right, and you might see why they're intimidating as we talk more about them.

E: Okay, okay. I'm intrigued, hit me.

H: Alright so that's what a fungus is and now I just want to answer the question what is the difference between a mushroom and a fungus because like I mentioned earlier there are fungi that produce mushrooms but not all fungi do that. So, a mushroom is the reproductive organ of some fungi meaning mushrooms are where meiosis takes place and the gametes are made and gametes are basically just any reproductive propagule. In animals of course the gametes are the sperm and the egg but in fungi those are the spores. So mushrooms are also called sporing or fruiting bodies. The spores are produced and released from a portion of the mushroom called the hymenium which in most of the popularly recognizable mushrooms is gills under the cap but in some mushrooms the hymenium can have pores or teeth or maybe folds that aren't quite true gills there can be a lot of different arrangements on the hymenium of a mushroom. So you can think of the fungus and by the fungus I mean like the network of mycelium you can think of that as an apple tree and you can think of the mushroom as an apple. So if you pick a mushroom the fungus is still in the substrate and it will continue to live even after you've taken the mushroom and you know identified it or whatever you're gonna do.

I: Or just kicked it.

H: Yeah so you're not you're not hurting the fungus itself.

I: Ideally don't just go kicking mushrooms though.

H: You might, you might be hurting the funguses chance at reproduction but you're not hurting the fungus. Mushrooms usually are composed of a stock or a stipe and then a cap on top but that isn't necessarily true of all mushrooms, like the one we'll talk about today doesn't have a stock or a stipe. Some fungi never produce mushrooms like I said. There's a large group of fungi that produce fruiting bodies that are shaped like cups instead of mushrooms so this group called ascomycetes they're like cup shaped and they'll just kind of be like sitting on the log or whatever it's growing on.

I: Yeah think about like an upside down contact.

H: Yeah or like a bowl sitting on a table.

I: Commonly, there's other forms. Pretty much every rule we can make with fungi there's exceptions.

E: I feel like that's all of biology but I do understand it's probably more so in fungi because we don't know that much about them.

I: I mean we're trying to describe an entire kingdom. Imagine trying to describe every single plant's basic shape.

H: Yeah so this is just an overview, just keep in mind that there are lots of exceptions to all of this that i'm saying.

E: Okay totally fair but also my mind is blown enough. So we can stick with the shallow level for now, please.

H: So we have the mushroom producing fungi and then we have fungi that produce cups instead and that's what their fruiting body looks like, there's another large group of fungi that never go through meiosis or sexual reproduction making them entirely asexual. These fungi produce spores that are genetically identical to themselves and they are called the fungi imperfecti.

E: What! That's such an offensive name. Did you just say imperfect.

H: Yeah the fungi imperfecti, I guess.

E: I am so offended right now on behalf of asexuals everywhere both the human variety where you do not clone yourself and the reproducing asexual variety.

H: You're perfect Ilana.

I: Asexuality in biology is very different than asexuality in humans, just a heads up.

E: I love you, Ilana it would be very cool if you cloned yourself but like also please don't do that, you'll get me a heart attack.

I: I don't really wanna.

E: All right cool.

I: But also, I got really confused the first time I heard the term asexual applied to a human, I was just like you... you can't. That... that's not how this works.

H: Right two very different meanings, yeah. To clarify do you want to define those and say how they're different Ilana?

I: Yeah so asexuality in biology is when something can reproduce by itself so oftentimes it's through like budding or fision, so like a cell can break into two cells and create two identical offspring or daughter cells and if that's its form of reproduction like for bacteria that's a sexual reproduction. But in humans we, we can't do that. We can't just like chop our arm off and grow another person, please don't try.

E: I'm very grateful for that, that's, that's a nightmare scenario right there. No thank you.

H: Imagine

I: Asexuality or the ace identity in humans refers to people who do not feel sexual attraction whether or not that means they want sex or desire it or are attracted in other ways, romantically or such to people, is all dependent on the person. It's also an umbrella term, so it's a spectrum and you can find yourself as graysexual meaning you don't feel sexual attraction often, demisexual you only are attracted to people you know very well, or anything in between.

E: Okay, super cool.

H: So yeah very, very different meanings but asexual people are perfect and asexual fungi are also perfect and I'm mad at these biologists who said otherwise.

E: Right! What is with the name.

H: And then there's other fungi that go through sexual reproduction and meiosis but they will produce spores directly from their mycelium and they won't produce any fruiting body at all. And then there's also another group of fungi that will produce fruiting bodies but they are not necessarily observable with the naked eye, they're microscopic and they're only a few cells tall. There's a lot of different arrangements in fungi but mushrooms are one type of fruiting body that fungi can produce.

I: And the most charismatic.

H: Yeah, the most easily noticed, usually too. It's the type of fruiting body that the fungi we will be talking about today produces.


[Discussion of the ecology & history of Shizophylum commune]


H: So, on to the ecology and the history of our species of interest shizophylum commune this species, also called the split gill mushroom is found everywhere on earth from coast to coast on North America as well as every other continent except for Antarctica as far as we know.

E: That's really cool.

H: Right. It's very widespread but there are a couple of species of fungi that we thought were widespread before and now we're finding out that they just appeared to be the same species. But once you sequence the genetic code, we found out that they're actually localized like they're a species complex so what we thought was one species is actually like 16 different species.

I: Yeah, this has happened if multiple times.

H: Yeah, this has happened multiple times. So like what we thought was one species is actually like a different species that occurs in Europe and then when it occurs in North America that's a different species. So they think that that might be the case here as well.

E: Oh not subspecies but separate species?

H: Separate species yeah, genetically.

E: I know for like other animals and plants because you know, my expertise is not fungi, that it's really common for populations in different continents to be considered separate subspecies because they have been breeding just with themselves long enough to have some genetic differentiation but okay, entirely separate species,very cool.

H: Yeah, yeah like they're genetically different enough that we feel comfortable saying they're several species not subspecies.

E: Yeah that makes sense, I suspect the animals move a little faster around the world than the fungi do because you know they can move.

H: Well you'd be surprised because we've found out that spores since they're airborne and they're super small actually can travel across oceans, like we've found spores sampled from the air that have come from fungi across the Atlantic, across the Pacific. So spores actually can travel very, very far.

E: Wow okay, I take it all back.

I: It's just whether or not they survive and also meet a compatible spore.

H: Yeah exactly they have to encounter the right substrate in the right environment and all that other stuff in order to germinate and actually make a mycelium and all that.

I: It's complicated.

H: Yeah so it's very complicated but it raises some questions because it's like hypothetically these things that like Ilana said diverged millions of years ago could have been interbreeding across continents this whole time but they haven't been. Which you know is interesting if anybody's looking for a PhD project or something.

E: Ii am intrigued spore dispersal is also understudied.

H: Yes.

E: Basically come study fungi you guys there's so much more to learn, its super interesting.

H: Right so shizophylum commune is ubiquitous. And it's a saprobe, meaning it's a decomposer so it grows on dead wood and it's the type of fungus like i said before it excretes its digestive enzymes and consumes the wood around it. So, it digests and lives on decaying wood, it can also sometimes be parasitic on living wood. And it's most often found on decaying hardwood sticks or logs and can be found pretty much year-round, and hardwood is deciduous trees if anybody doesn't know. I feel like nobody explained that to me and they just like waited until I understood.

I: It's just assumed.

E: Yeah they just talk about it, yeah hardwood is is deciduous trees.

H: Hardwoods are deciduous trees which lose their leaves every year. Soft woods are coniferous trees which don't lose their leaves ever so like pines and spruces and all that.


----TW: Discussion of lung disease and sinus disease in humans. ---- (Time stamp: 25:30)

So this fungus is most commonly a saprobe on decaying hardwoods however it can also be pathogenic in humans, o it can cause diseases in people. In patients who are immunocompromised shizophylum commune mostly infects the lungs but can also infect the sinuses.

I: Creepy.

E: Oh that sounds intense and not very fun.

H: No. It's not super common like I found a review paper from I think 2013 that had record of, I think, around 70 cases worldwide most of which were recorded in Japan. But it's interesting because the diseases that this fungus can cause in people, like the disease is called something different depending on where the fungus is growing, I assume because the symptoms are different. So some of the diseases that I found it caused were called like there was allergic bronchopulmonary mycosis, pulmonary fungal ball, I don't know what that means. Pulmonary means lungs, right? Most recorded cases of those two have been in Japan, like I said but they don't think that that is necessarily because shizophylum commune is more virulent in Japan but maybe just because medical staff in Japan are more aware of it as a pathogen and are more likely to be looking for it and to diagnose it than medical staff in other countries.

I: I'm surprised it's the same fungus as the decay, like the wood decayer because that's a very different substrate.

H: Right. But they have isolated it from people and genetically sequenced it and…

I: Wild.

H: Yeah right but it can also cause fungal sinusitis or bronco pneumonia.

----End of discussion of lung and sinus disease---- (time stamp 27:06)


H: So that's what it does in the environment. Like Isaid it does produce a mushroom as a fruiting body and this species was described by a man called Elius Magnus Friese in 1815. And a little bit about Elias Friese, he grew up the son of a poor rural clergyman in southern Sweden he came of age and went to school during a very tumultuous time politically. Sweden was engulfed in the Napoleonic wars in which Sweden took present-day Norway from Denmark and Denmark sided with Napoleon. So he grew up during the Napoleonic wars and that's when he went to college, so all that was happening. He learned botany as a child from his father, so he was inspired to go to school for botany at Lund University. His dissertation was on the flora of Sweden and while there he did some work in Copenhagen where he was introduced to illustrations of quote unquote hymenomycetes which is another word for mushroom producing fungi. So he found these beautiful pictures of mushrooms and was just so enamored that he was asked by the botanists in copenhagen to correct names that were given to these mushrooms in the illustrations because some of them clearly didn't make sense, not sure why or what about them made these names wrong but they needed his help. So he did that work he corrected all the names that were going into this guide that was being published and as well as a ton of names of fungi that had already been published. So he went back and corrected a lot of things as well and during that time in addition to mushrooms Friese also published on green plants and lichens. So he was an all around mycologist botanist. He did all that kind of stuff. So after working on this mycological illustration project in copenhagen Friese went on to lay the groundwork for pretty much all of modern fungal taxonomy and now is considered one of the founders of the field. Taxonomy is like, basically just the naming of things based on how they're related. So Freise, one of his most important works was his three volume Systema Mycologicum, it was written entirely in Latin and in this he described fungi based on their physical characteristics of their fruiting bodies, primarily based on spore color in the structure of their hymenium or their spore bearing surface. So whether they had gills, folds, teeth, pores like I mentioned earlier, they can be very different.

I: If you hear of someone taking a spore print, that's one of the ways you can check spore colors.

H: Yeah

E: Okay.

H: It's relatively easy. You just kind of like cut the stem off the mushroom put the hymenium on a piece of paper and like put a bowl over it and then the fungus drops its spores like it normally would but the wind isn't there to pick it up so they just kind of deposit on the paper and you can observe what color the spores are.

I: It makes really pretty patterns, especially in guild mushrooms.

H: That's probably how he looked at the spores because Elias Magnus Friese was very against microscopes.

I: That's so weird.

H: Right! He thought that they were primitive instruments of the day that did not provide any information he could not get by other means.

I: Primitive compared to his eyes!

Laughter

H: Apparently, apparently he just thought his eyes were better.

E: Talk about arrogance. Okay.

H: But like I get not wanting to f***ing look in a microscope for your whole career but like.

E: Like I understand the urge but to say you don't need it. Wow.

H: And while I was reading about him, I questioned whether he should still be considered the father of modern taxonomy because. This is a quote from my source, okay are you ready? “Apart from the scientific influence he received from his mentors young Friese was also much influenced by the dominating spiritual thinking of the period, romanticism. Thus the god-created perfect world is especially seen in his taxonomy in Systema Mycologicum volume 1, where all fungi are divided into four classes, each class into four orders, each order into four tribus, and the number of species in each tribus,” which I guess in modern terms would be genus “often was multiple of four.” So in genus Amanita he had 12 species, in Lepiota he had 12 species, in Armalaria he had 12 species and so on and so on.

I: He really liked the number four.

E: I guess so.

H: Yeah so my thing was like how can we say that he was like objectively describing things based on their morphology when he was like making them fit into these predetermined boxes of four.

E: Look the man thought his eyeballs were the same as a microscope.

Laughter

I: At least he like put them into a grouping probably no one had bothered they were just like these are weird. It's not a plan,t it's kind of squishy, eeeh.

H: Right.

E: Clearly he did it first. Also just as clearly the first scientist to do it is not always the best scientist to do it y'all.

H: True. Well apparently someone tried before him and he did a better job because remember he corrected like that guy in Copenhagen.

E: Oh that's right, that's fair. I already forgot about that I was very focused on the eyeballs equal microscope bit of the story.

H: Oh right. Not to downplay his passion because this source also had a lengthy section about how a lot of descendants of freise are still in the mycology field and in the botany research field well.

E: Hey that's cool if he passed it on to his family. That's really cool. I like that.

H: Right there are descendants and like a good portion of people working who were like inspired by his passion.

E: That's pretty cool.

H: Which I will give him was admirable. However I'm just saying there may have been some flaws in his work as well.

I: That's why science is constantly evolving.

E: Right and that’s why we spend so much time double checking everybody else's work.


(Species Description)


H: Exactly. Okay so ,now if you'd like to look at the pictures in the link I sent you. You're welcome to describe the species as you see it.

E: My first thought is fluffy.

I: I mean definitely some of the first few pictures are very fuzzy looking. I feel like I've seen this fungus before. Like I’m almost positive I have pictures of it on my phone somewhere.

H: You've probably seen it somewhere.

E: It's definitely got a lot of grooves, the underside to me kind of looks like a seashell you know when you pick up a seashell and it's got the lines on the top. And I can't think of what kind of seashell it is, there's a specific type.

I: Yeah it's kind of I would definitely say like a seashell shape, it looks like the gills are facing upwards maybe? That or there's just a lot of underneath pictures.

H: Yeah I think they're taken from underneath.

I: Okay that makes more sense. Oh, that's a cool picture someone took a photo with the mirror underneath it. So the top is pretty light colored looks like an uneven edge, beautiful gills. I'm loving these gills. Is every guild doubled or is that where it gets its name like the guills look like they're split?

H: They are double gills and that's why it's called the split gill fungus.

I: Yeah so like every gill is like two smushed together.

E: The color seems to range from white to like a pinkish coral beige. Most of them seem to be about the size of quarters or smaller.

I: Not seeing too much of a stem. It looks like it's pretty much attached directly to its substrate.

E: Yes that's a good point. Oh wait, I think there's a picture with some stems but yeah almost all of these look like they're coming almost directly out of the substrate and with like maybe a very short stem.

I: Like from the side not the center. You think, do you think we got it?

H: Yeah I think you did a good job here's the official description. The mushrooms of shizophylum commune grow alone or more frequently clustered closely together in like groups. The cap of each individual mushroom is 1-4 cm across. It's considered fan shaped when attached to the side of a log and irregular or shell shaped when it's attached above or below. It's finely hairy to velvety or almost granular on the upper surface. It's dry texture-wise. The flesh is whitish or grayish or brownish, sometimes developing concentric textural zones on the top of the cap. So those zones if they exist will look kind of like concentric rings around the edge of the fan. The gills of this mushroom are considered distant, folded together and they appear split down the middle. They're whitish to grayish but I also think i've seen in the field, like you said Elizabeth, they look kind of pinkish too, even almost violety. Like they can be very beautiful when they're fresh. The stipe on this species is absent because the fan just kind of directly attaches to the log like like you mentioned. The flesh of this mushroom, like if you cut the mushroom in half like what the inside of it would look and feel like, the flesh of the mushroom is tough whitish though it's often listed in guidebooks as inedible, especially guidebooks in temperate regions this is due to taste preferences rather than this mushroom being toxic. It is not preferred in temperate regions like i said due to its tough flesh, it's just like hard to cook and chew on but it is widely consumed in mexico in the tropics.

I: Fair warning though if you want to try eating any fungi make sure you're sure about the identification don't, don't just go out and be like that's totally this munch. Bad decisions.

H: Oh good thing to say,listeners if you're not familiar with mushrooms just don't, don't eat ones that like are out in the wild.

E: Even if you are I feel like I've gone on mushroom hunts with these guys and I'll be like oh can I eat that and they'll be like well there's a 90% chance it's safe so no.

H: yeah there are lots of edible mushrooms with non-edible lookalikes. Just don't eat a mushroom unless you are absolutely 100% certain what species it is. So yeah, the odor is non-distinctive, it doesn't really smell like anything. The spore print. if you find a fresh specimen and put it on paper, the spore color will be white. And then microscopic features are mentioned because a lot of times there are mushrooms that to the naked eye will appear to be the same species but are sometimes distinguished by different features on their spores. So the spores of this mushroom are 4 to 6.5 by 1.5 to 2 micrometers. They're very very very small you can't see them with your naked eye like unless they're all deposited on one another in a spore print. The shape of these spores is considered sub-cylindric or sub-ellipsoid and in this case sub just means imperfect so they're imperfectly cylindric or imperfectly ellipsoid shaped. The texture of the spores is smooth. So that's what shizophylum commune looks like.


(fungal sex and gender)


H: And now I want to talk generally about sex and gender in fungi to then explain why there are so many sexes in this specific fungus. So we're kind of starting to get into why it's queer because as you'll see all fungi are kind of queer.

E: Awesome.

I: I think I found pictures of it on my phone.

H: Awesome look at that you have seen it before. Alright cool. So sex and gender and fungi, as we've said in previous episodes biological sex is not necessarily defined the same way by biologists as by people in the general public. The generally accepted definition of biological sex has to do with genitalia and what you're assigned at birth based on the shape of those genitalia and you know stuff like that but in actual biology biological sex is related to the gametes an organism produces not to its genitalia. So how is sex determined in fungi. Let's first go over what gametes are and what their purpose is because gametes aren't really used the same way in fungi as they are in animals. Like i said the gametes in the human body are the egg and the sperm, and the egg and the sperm are different because they've gone through meiosis. So, they have half the number of chromosomes that the normal human body cell has, right. So think about it your, any cell in your body normally has two sets of chromosomes. One set from your mom and one set from your dad because these cells have two copies they're called diploid right. This is probably a review of like high school biology for a lot of people but just to get everybody on the same page. After your diploid body cells go through meiosis the number of chromosome sets in the cells goes from two to one. So that's where your egg and sperm get one copy to then give to your children. So those egg and sperm since they have one copy of each chromosome are considered haploid instead of diploid and then during conception when the egg and the sperm meet and fuse their nuclei containing their chromosomes also fuse and then they produce a zygote that again has two sets of chromosomes, right, the one from the egg and the one from the sperm so now the zygote is again diploid, right. And then that cell divides and copies itself and produces a whole diploid human body. So essentially to sum it up, the purpose of gametes for animals, is just to be like a vehicle to bring together two haploid nuclei in the gametes so that then they can fuse to form a diploid nucleus in the zygote.

E; Okay, okay I'm pretty sure I'm following that.

H: Okay cool. So the purpose of gametes is to meet and make a diploid zygote that's the purpose. In mushrooms and in mushroom producing fungi the gametes are the spores and they are all the same size, there's not a large one in a small one to be like okay this is the male sex and this is the female sex, that doesn't exist. There's no way to to be like this is the large and this is the small. These spores like we said they're often distributed by air and when they encounter a suitable substrate they will land on that substrate and germinate into a network of mycelium. But therefore fungi don't have a small and a large gamete to fuse together because like I said that doesn't happen they just land on the dirt or the the wood that they grow on and then grow into a mycelium there's no fusion so how do they have genders or sexes or sex? So the spore has landed on its substrate it's germinated and divided into a mycelial network, right that's the body of the fungus and while it's growing when the mycelial cells of one fungus physically encounter the mycelial cells of another fungus, and remember both of these are still haploid the entire mycelium is haploid, so when they physically encounter each other and those fungi are compatible, they exchange haploid nuclei and the contents of their cytoplasm combine. And this process is called plasmogomy but their nuclei don't fuse which is unique. Because in animals the gametes fuse and the nuclei fused and the zygotes formed immediately right, that's not the case here.

E: What!

H: Yeah, the cells touch each other and then the contents mix. So that's where the word like plasmo and plasmogamy comes from the cytoplasm right.

E: Right.

H: All the liquid inside the cell and all of its contents they kind of exchange that including the nuclei but those, like I said, those nuclei don't fuse. So you end up with this network of mycelium that now has two genetically distinct nuclei in them and this phase is called the dikaryotic phase. This doesn't exist in humans and “di” meaning to “kary” meaning nucleus which is pretty cool. And this dikaryotic phase can last a very long time. Then, when the right stimuli have been encountered and the fungus is ready to move on to the next stage, the nuclei fuse and this process is called karyogamy. So there is plasmogamy the combination of the cytoplasm and now there's karyogamy which is the fusion and the combination of the nuclei and this is actual sex. So, the nuclei finally fuse the diploid zygote is formed, right, finally but the diploid zygote doesn't last very long it doesn't develop into its own organism. Meiosis immediately happens again and this occurs in the mushroom itself. Karyogamy happens but then meiosis happens so the haploid spores are formed again and that is the fungal life cycle for mushroom forming fungi at least. The main difference between fungi and humans our haploid cells don't divide and form like a whole network, our diploid cells do that. In mushrooms their haploid cells divide and form the mycelial network and their diploid cells they don't last very long. So it's kind of the opposite and like I said kind of queer in itself.

E: Fair, fair.

I: Fungi itself are kind of queer.

H: Yeah all fungi. So, that's the fungal life cycle, now on to mating type recognition in shizophylum commune. So this is getting into how this fungus can have over 23,000 sexes, right. I still haven't quite answered the question of like how we can define a sex in a fungus because like I said biological sex is the small and the large gamete, they don't have small and large gametes they have spores all of the same size. In fungi sexes are called mating types and this is because there aren't necessarily visible or microscopic or just like physically observable differences between mating types. They don't look different, they don't function differently all that is different about them is their genetics. So to recognize compatible mates fungi use something called a G-protein coupled receptor and these are proteins that exist on the, in the membrane of the cell. So they're within the membrane, the protein has a portion sticking out of the cell in a portion sticking into the cell and this protein is used by the fungus to sense stimuli from the environment around the cell.

E: Kind of like eyeballs…

H: But very very different and not visible, right. It's just a way for it to interact with things around it, like this protein can bind to chemicals and signals in the environment. Specifically, these G-protein coupled receptors are found in a ton of different organisms but they're used to sense different chemicals in each organism and in fungi they are specifically used to detect peptide pheromones produced by potential mating partners.

E: So kind of like a touch sensor with the extra ability to sniff out the mates.

H: Right, right. So like I said like they have to get physically close to each other to sense each other to then come into contact to exchange cytoplasm. So they get kind of close to each other and then this one fungus its G-protein receptor will start receiving and binding to a pheromone of a potential mate and then that fungus, since that protein is picking up that signal will start to grow toward the other mycelium until they eventually physically touch and then they can do plasmogomy and karyogamy and the rest of it. But first that chemical recognition has to happen. So in quote-unquote lower fungi, according to my source but like I said I don't like using terms like that and this source just means yeasts, so these are single-celled fungi that don't ever produce a multi-cellular fruiting body but I'm just using this as an example to kind of explain a very simple mating type system.

E: Okay.

H: So, in yeasts there's a single gene that determines mating type and there are two alleles of that gene and just as a reminder of the difference between genes and alleles because like I said like genetics is very important in determining the sex of fungi. So that's what most of the rest of this podcast is going to be talking about. So a gene, you can think of like the gene for eye color for example, the gene is for eye color the gene is a specific location on the chromosome the alleles are two different possible versions of that gene that an organism can have.

E: So like green or brown.

H: Exactly. Exactly. So the gene would be for eye color and then two possible alleles for the gene are like Elizabeth said green or brown, exactly. So in yeasts there's one gene responsible for determining mating type and it has two alleles, so therefore there are only two possible mating types or quote unquote sexes because mating type is as close as fungi come to having separate sexes and in yeasts these two different mating types are called big A little a or plus and minus. And the receptor protein for one type is only activated by the pheromone produced by the opposite type.

E: Oh so as close as hetero as fungi get.

H: Yes exactly. So like big A will only recognize the pheromones of little a and it can only mate with little a. If a big A and a big A encounter each other plasmogamy and karyogamy and all that doesn't happen.

E: No homo.


(Why shizophylum commune is queer!)


H: No homo. So now into why shizophylum commune is so queer.

E: So incredibly queer.

H: In sshizophylum commune there are two mating type factors involved in determining mating type and these mating type factors are called a and b. This is this is also kind of queer. In this species plasmogomy can occur regardless of mating type of the two partners in order to be considered completely different mating types they have to differ in both mating type factors a and b.

E: Okay so hang on. So let me see if I can come up with a comparison for this. So it'd be like if you were trying to say two people looked different right, because i'm still in the eye color thing from earlier. So it would be like one person would have to have like brown hair and green eyes and the other person would have to have like red hair and brown eyes to be considered different. If they both had the same eye color and hair color then they wouldn't be different even if it was just one of the two.

H: Exactly if you're saying like a is hair and b is eye color yeah they have to be different in both of them. If they have the same thing for a and different things for b, plasmogomy can happen because like I said plasmogamy can happen regardless of mating type in shizophylum commune but the nuclei don't end up fusing. Because mating type factor a controls one part of the nucleus like fusion process and mating factor b controls the second part of the process.

E: So they do the the feeling up but not the trading.

H: Yeah like if they're different in one factor one part of the process can't happen so therefore the whole thing doesn't end up being a success.

I: No baby fungis.

E: Okay no reproduction.

H: Exactly so they'll get into the dikaryotic state but the fusion of the nuclei won't happen.

E: Oh it won't work.

I: Yeah normally this is to prevent like self-compatibility and like replicating of the same genes which can lead to mutations that are not helpful and a decrease in diversity. But having a double requirement is still going to an extreme that must have at some point had an advantageous reason we would think.

H: Right.

E: Yeah.

H: So I was talking about how the process of sex can be interrupted if the two mating types are the same in mating type factor a or b. If they are different in all of them, if they're completely compatible and they can have sex. They will go through plasmogomy and then the nuclei of the mate will be transported throughout the entire mycelium, so that each cell in the end will end up with two haploid nuclei that will then form one diploid nucleus because you don't want to end up with all of the nuclei in the part of the fungus that's touching the other fungus. Like you need the nuclei in the whole thing. So that's the, that's a prerequisite to karyogamy and that is the part of the process that gets interrupted if the two mating partners don't differ in mating type factor a or b . That part of the process won't happen, therefore karyogamy cannot occur. But if that redistribution of the nuclei does happen karyogamy occurs after the mushroom is produced in the gill surface or the hymenium and then immediately after like I said meiosis happens so that diploid zygote doesn't last very long.

E: Okay but it does successfully transfer to the next stage.

H: Yep and then like I said if the two mates have the same allele in a or b nuclear fusion doesn't happen. So, what makes this species exactly so complicated is that it's not just a and b like that's a and b are not single genes a and b are each composed of two separate genes a alpha and a beta and then b alpha and b beta and then each of these four genes has not just two alleles but like a lot of alleles.

E: Okay. I see how we're getting to those 23,000s now.

H: Right a alpha has nine alleles, a beta has around 32 alleles we're not positive, b alpha has nine alleles, and then b beta also has nine alleles.

E: Okay you guys I just tossed my pencil down. I was like I’m gonna do the multiplication to see what I end up and I was like nope not doing it. We're not going there.

H: Right I'm not good at math. I can't do that math in my head but somebody who has done that math has figured out that it comes out to 23,328 possible mating types or sexes.

E: Love that. That is so bad.

H: Right.

E: Oh my god that's so cool. Okay, okay wow you know that really gives me a sense of appreciation for our like two chromosomes. Thank you for that system. I know that we've been able to express it differently which is absolutely amazing but like i'm glad we didn't start with 23,000 and then have to try to figure out how to express that.

H: Right I'm thinking about how hard it would have been to pass like high school biology if I'd had to like memorize how this genetic system works like it was so much easier just learning x and y.

E: Yeah, oh no.

H: Not to say that x and y are like the only options in humans because we also learned in biology that that is not the case.

E: Oh absolutely not.

H: Humans can also have you know xxy, xyy, xxx, there are lots of different options in humans as well.

E: yeah there's tons of options so even for the folks that think biological sex is the only version of gender that counts, which by the way I hope you're listening to this podcast because I want to enlighten you but like also why are you here. But if you are one of those people there's still more than two biological sexes so…

H: Because no matter how you define it there's more than two because if you define it incorrectly by genitalia there are intersex people, if you divide it by chromosomes there like we said there are lots of different chromosomal arrangements. No matter how you look at it there's more than two. If you look at, the the big thing right now is hormones there's going to be a whole f***ing spectrum of hormone levels in people.

E: Yeah absolutely.

I: Hormones are wild.

E: Oh my god so wild. Yeah everybody thinks that everything should be just like this box and this box and I hate to tell you but biology doesn't do boxes very well there's always a sliding spectrum of options.

I: Well where we're good at making boxes, things just don't stay in them.

H: Like we said we make these generalizations but there are always exceptions and there are always a lot of them.

E: And there's so much beauty in the exceptions too. They're really special there's something to be celebrated, don't cry about your broken box.

H: Yeah no your box just got way bigger and that's beautiful and way fuller of lots of different more things so.

I: Or you just got a whole lot of them that's fine and funny shapes.

H: Yeah or lots of different boxes, you're right. However it's arranged yes. And with that we conclude our episode on shizophylum commune or the split gill mushroom thank you so much for listening.

I: Thank you hannah and thank you funguys fungals and fun-binary pals!


Exit music


H: Queerly Natural was created by Ilana Zeitzer, Elizabeth Fuhrman and Hannah Rhoden with music by Migfus20, thank you Migfus for putting your music in the creative commons you are very talented. Visual design for the show is done by Ilana Zeitzer. To get updates about the podcast follow us at queerlynatural on facebook, twitter, and instagram we also upload all of our sources and episode transcripts to our website queerlynatural.com. Above all else if you liked what you heard today tell your friends. Thank you so much for listening and keep an eye out for our next episode coming at a later date to be determined in the meantime stay queer because queerly it's natural.


Sources:



Kothe, E. (1995) Tetrapolar fungal mating types: Sexes by the thousands. FEMS Microbiology Reviews 18(1996) 65-87


Kothe, E. (1999) Mating types and pheromone recognition in the Homobasidiomycete Schyzophyllum commune. Fungal Genetics and Biology 27(2-3) 146-152 https://doi.org/10.1006/fgbi.1999.1129


Scharping, Nathaniel. (2017) Why This Fungus Has Over 20,000 sexes. Discover magazine https://www.discovermagazine.com/planet-earth/why-this-fungus-has-over-20-000-sexes


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