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Okay, let's unpack this.
Imagine a perfect picnic.
You know, champagne,
fresh crusty bread, some creamy camembert cheese, maybe even a hint of truffle in your pate.
Now picture the meadow around you.
Maybe a big pine tree giving shade.
What if I told you that from the drinks to the food, the very health of that meadow, that tree,
fungi are playing a starring role.
Sometimes good, sometimes, well, a bit naughty.
Welcome to the deep dive.
Today we're really digging into chapter one of Grace Kendrick's The Fifth Kingdom.
Our mission, to give you a shortcut really to understanding the absolute basics of mycology that's the study of fungi.
We'll look at how scientists categorize life, the surprising twists in figuring out what fungi are and why knowing this stuff is just so vital to appreciating another huge impact.
We're covering kingdoms, classification, nomenclature, and yeah, the silent crisis of biodiversity.
It's fascinating, isn't it?
Fungi aren't just like simple organisms.
They represent this fundamental, incredibly versatile way of life.
This chapter really lays the groundwork.
It helps us untangle why defining a fungus is way more complex than you might think and how our understanding keeps changing, you know, with new science popping up all the time.
Right.
So before we dive specifically into fungi, let's zoom out.
Big picture.
How is life itself organized?
We usually think, okay, plants and animals, but modern biology, it recognizes at least seven kingdoms.
To really get where fungi fit, we kind of have to start at the beginning.
Yeah.
Exactly.
The most basic division in all life on earth is between prokaryotes and eukaryotes.
Think of prokaryotes as life's sort of original simple cells, DNA just floating around getting stuff done.
They showed up billions of years ago.
Eukaryotes, though, they're like the cellular architects.
They evolved maybe two billion years ago.
They built complex internal structures like a nucleus to keep their DNA organized in chromosomes and these little power plants, mitochondria.
It wasn't just, you know, a small upgrade.
It was the ultimate biological toolkit.
It unlocked the potential for almost all the complex life we see, us, plants, animals,
and fungi.
So this eukaryotic cell evolution, it wasn't just a minor tweak.
It was like going from a basic calculator to a supercomputer, basically.
And part of that upgrade involved new ways for cells to divide.
Precisely.
Eukaryotes developed mitosis.
That ensures really accurate copying of genes when cells divide for growth, repair, that kind of thing.
And then there's meiosis.
That's reduction division.
It creates unique sex cells, or gametes.
This process, plus something called crossing over, constantly shuffles genetic information.
It creates variation, which powers evolution.
It's really key to eukaryote complexity.
That's incredible.
And here's where it gets really interesting for me.
Multicellularity.
Suddenly cells could specialize, work together, build something bigger.
Absolutely.
Game changer.
When organisms became multicellular, cells could take on different jobs.
Specialization.
This division of labor led to tissues, organs, complex life.
And with multicellularity, these three fundamental ways of life really emerged.
Producers, like plants making their own food through photosynthesis.
The green specks.
Consumers, like animals, eating others.
And decomposers.
And that's where fungi primarily step in, recycling all the organic matter after things die.
Okay, but hold on.
You said fungi are decomposers.
But the book also mentions fungi can fit into two kingdoms.
How does that work?
Does that mean our whole idea of fungus has been kind of off?
Well, off isn't quite right.
It's more that our understanding gets refined.
The word fungus is often used functionally, ecologically.
It describes a certain lifestyle.
Things that absorb nutrients, break down stuff, reproduce by spores.
So we recognize what we call chromastan fungi, sometimes called pseudofungi.
Pseudo meaning false.
Exactly.
And then the umacotitan, or true fungi, it just shows that this successful strategy, this lifestyle,
evolved more than once in different lineages.
It's convergent evolution.
Okay, so before we get into true versus pseudo, give us that initial functional definition again.
What makes something fungus -like?
Generally they're eukaryotic, so cells with nuclei.
They're heterotrophic, can't make their own food.
Crucially, they are osmotrophic.
They absorb dissolved nutrients from outside.
They eat like animals.
Oh, okay.
Absorb, don't ingest.
Right.
And they typically develop this diffuse branched body, little threads called hyphae.
These hyphae make up a network called a mycelium, and they reproduce via spores.
That's the basic toolkit.
That makes sense.
So this idea of true fungi, the umacota, it's relatively modern then.
And it sounds like some groups we used to call fungi got, well, kicked out.
Who were these biological outcasts?
Uh -huh.
Outcasts is a good way to put it.
It shows how science corrects itself.
These outgroups, they were initially lumped in because they looked and acted like fungi, but molecular data showed they weren't related.
They include members of Kingdom Chromista, like the umicetes.
These are actually more closely related to brown algae, water moles, potato blight, things like that.
Wow.
Algae.
Not fungi at all.
Not true fungi, no.
And then from Kingdom Protozoa, you have things like the slime molds.
Totally different evolutionary path.
The key thing here is they're convergent analogs.
They arrived at a similar solution of fungus -like lifestyle, independently.
Not homologues, meaning sharing a common ancestor for that trait.
Precisely.
And the differences are fundamental, like umicetes have cell walls made of cellulose, like plants.
Okay.
True fungi, the umicota.
They primarily use chitin, that's the same stuff in insect shells.
Chitin.
Okay, totally different chemistry.
Totally different.
And other things too, like how they make certain amino acids, the structure of their mitochondria.
These details tell us their separate lineages.
Wow.
So discovering these deep differences just redrew the map.
Once these pseudo fungi were moved out, how did our picture of the true fungi, the umicota, keep changing?
Because it sounds like it didn't stop there.
Oh, it definitely didn't stop there.
Once the decks were cleared, so to speak, we initially thought true fungi had about five main phyla.
But then molecular data, DNA sequencing mainly, just blew things open again.
It wasn't just adding names, it changed our whole concept.
It showed some fungi adapted by losing traits we thought defined them.
Losing traits.
Well, take microsporidia.
Tiny intracellular parasites.
We always thought they were protozoa.
They don't even have cell walls when they're active.
And no mitochondria.
But their DNA and chitin and their spores, turns out they're fungi.
Weird, highly adapted fungi.
No way, that's bizarre.
Right.
And then we found anaerobic fungi living in cow stomachs, the neocalamastiga mycota, they also lack mitochondria, and maybe even the cryptomycota, the hidden fungi, found only as DNA in ponds initially.
They might lack titan walls entirely, and maybe even engulf food particles.
Still debated, but DNA links them to fungi.
My head is spinning, so the definition keeps getting stretched.
If fungi can lose chitin walls, lose mitochondria, how do we even define them now?
Is the current definition solid?
It's definitely an evolving definition, but we have a working one.
The updated minimal definition is, absorptive heterotrophs.
Meaning, no chloroplasts, not photosynthetic, don't ingest food, they usually produce spores with chitinous walls and often have multi -nucleot walled hyphae.
It has to allow for these evolutionary losses.
And yeah, molecular data is powerful, but it's not perfect.
Different genes evolve at different rates, which can sometimes create biases in the evolutionary trees, and it's always being refined.
Okay, so with all these discoveries, reclassifications, constant change.
Scientists need a system just to keep track, right?
That's where classification comes in.
Like a giant, ever -updating library catalog for life.
Precisely.
Classification is all about information storage and retrieval.
Creating that cognitive map, you need to navigate diversity.
A big step was the higher -level phylogenetic classification of the fungi in 2007, based heavily on molecular data.
It formally excluded the oomacids and slime molds, and it reorganized a lot of traditional groups like the old zygomycota got split up, and the ascomycota and basidiomycota, which
most known fungi, mushrooms, yeasts, lichens, rusts, smuts, got much more detailed subdivisions.
Right, and part of that system is the naming convention, the binomial nomenclature, right?
These Latin names, like homo sapiens.
Yeah, the binomial system is key.
Every species gets a unique two -part name italicized.
First part is the genus, capitalized.
Second is the species epithet, lowercase.
Genus and species.
Right.
So homo is the genus, sapiens is the species epithet.
The common mushroom is agaricus brunessens.
Agaricus is the genus, brunessens the specific species.
Only the full two -part name is unique.
And this fits into that bigger hierarchy, kingdom, phylum, class, order, family, genus, species, like nested boxes.
Kingdom fungi,
phylum, basidiomycota,
all the way down to agaricus brunessens.
Exactly.
Each level groups things by shared features, getting more specific as you go down.
Okay, clear roadmap.
But why not just use common names?
If I find a mushroom, I call it a field mushroom or whatever, it seems easier.
It seems easier, yeah.
But for science, common names just don't work reliably.
Three big reasons.
One, they change everywhere.
What's a field mushroom here might be called something else a hundred miles away or in another country.
Okay, inconsistent.
Two, the same common name often gets used for totally different things.
Think Robin, different birds in Europe and North America, confusing.
And three, they can be misleading.
Like we said, Irish moss is an alga, reindeer moss is a lichen, neither is a moss.
Got it.
So Latin avoids all that.
Pretty much.
Latin is stable, a dead language, so it doesn't change much.
And it's international.
No single modern language gets priority.
It's a universal standard.
Makes sense for global science.
Yeah.
But you mentioned one little hiccup, the graphium example.
Ah, yes.
That's a recognized flaw.
Sometimes the same generic name, the genus name, accidentally gets used in different kingdoms.
So graphium is a type of fungus, but it's also the genus name for a type of swallowtail butterfly.
Whoops.
Yeah, it's a problem, especially now we know fungi are actually evolutionarily closer to animals than plants.
There's no easy fix for those historical overlaps right now.
Okay.
Now that we know how they're classified and named,
let's talk numbers or rather the lack of known numbers,
biodiversity.
We hear that word a lot.
But for fungi, it sounds like we're mostly in the dark, a huge biological frontier.
It really is a stark contrast.
Think about birds or mammals.
We know pretty much all of them.
Finding a new species is massive news.
For fungi, mycologists find new stuff constantly, every day practically, especially with DNA sequencing of soil, water, finding fungal DNA never seen before.
We've officially described maybe around 100 ,000 species, but everyone in the field knows that's just scratching the surface.
So how many might be out there?
Well, David Hawks were thinking for this really clever estimate back in the 90s.
He looked at Britain, which is well studied mycologically, found about a six to one ratio of known fungi species to known flowering plant species there.
Six fungi for every plant.
Roughly, yeah.
So he extrapolated if there are about 250 ,000 flowering plant species globally, multiply by six.
That's a 0 .5 million fungi.
That's his estimate.
1 .5 million fungi worldwide.
Maybe more, maybe less, but it gives you a sense of scale.
Wow.
1 .5 million, and we know maybe 100 ,000, so like six or 7%.
Something like that.
It's pretty shocking, really.
It means the vast majority, over 90 % of the world's mycota, the fungal diversity, is undescribed.
It's a massive task for generations of scientists.
And here's the really concerning part, isn't it?
This huge unknown.
It's not just sitting there waiting.
Exactly.
That's the tragedy.
Human activities, habitat destruction, climate change are undoubtedly driving a fungi extinct.
Many before we even know they exist.
It's hard to document, right?
Especially for tiny microscopic fungi or ones that only fruit rarely.
How do you prove something's gone if you never formally described it?
A silent extinction.
Pretty much.
But we see signs.
Like Bridgiporus nobilissimus, a huge, rare bracket fungus in old growth forests in the Pacific Northwest.
It's endangered now because its habitat is vanishing.
In Europe, they have red lists tracking fungal decline because they have centuries of records.
North America doesn't really have that baseline, which is a problem.
And like Dr.
Bob Murphy said, protecting charismatic animals, the big fuzzy ones, protects forests.
And protecting forests protects everything else.
Especially the fungi, which are producing the majority of new pharmaceuticals.
Exactly.
That's the connection.
So let's bring it back to us, the listener.
Why should you care about these unseen species vanishing?
What's the real world impact?
It's immense.
Fungi give us life -saving stuff, penicillin, obviously, but also cyclosporine, the immunosuppressant that makes organ transplants possible.
There's even research on fungal compounds for diabetes.
Huge radical potential.
Huge.
And ecologically, they're the master recyclers, breaking down dead plants and animals.
Without them, nutrients would be locked up.
Plus, they form essential partnerships, mycorrhizas with plant roots.
Most plants depend on these fungi for water and nutrients.
Healthy ecosystems rely on them.
So losing fungi means losing potential cures and undermining entire ecosystems.
Absolutely.
And this realization, this gap in knowledge, has led to things like all tax of biodiversity inventories or ATBIs, like in the Great Smoky Mountains National Park.
They estimate maybe 20 ,000 fungi species live there.
20 ,000?
Yeah.
But guess how many are officially known and described?
About 2 ,250.
Wow.
So less than 15 % are known, even in a protected park that's being studied.
Exactly.
It highlights the scale of the challenge.
These ATBIs are trying to speed up discovery, but it's a race against time.
So pulling it all together.
What we've seen today is that the fungal world is just incredibly complex, way more diverse, and far more important than most people realize.
Their evolution, their classification keeps changing, their biodiversity is vast and threatened.
They really are this fifth kingdom demanding our focus.
Absolutely.
We've walked through the kingdoms of life, sort of redefined fungus by separating out the pretenders, learned the rules of the naming game, and stared into this huge, mostly unknown abyss of fungal diversity.
It's clear these aren't just mushrooms on pizza or moldy bread, they're essential players everywhere.
Food, medicine, the environment.
Which really makes you wonder, doesn't it?
What other secrets are hidden in that massive, undescribed 90 % of fungi out there?
What cures?
What ecological rules we don't even understand yet?
What truly bizarre life forms are waiting?
And how will our understanding keep evolving?
We really hope this deep dive gave you a new appreciation for fungi, and a solid foundation if you're studying this stuff.
A big thank you from us, your guides here on the deep dive, and from everyone at the last minute lecture team for joining this mycological adventure.
Keep exploring, keep asking questions, and maybe keep an eye out for a hidden fungus or two next time you're outside.