September 10, 2020 • 46 mins
Lichen are incredibly widespread and easy to take for granted, but these composite organisms are some of the most fascinating lifeforms on the planet. In this episode of Stuff to Blow Your Mind, Robert and Joe explore their remarkable qualities.
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Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind, production of by
Heart Radio. Hey you welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick. And
today we're gonna be talking about lichens. That's right. I'm
excited for this one because the lichen are the type
(00:25):
of life form that are are easy to take for granted,
but at the same time are in more places than
you think, and are of course far more complicated and mysterious. Uh,
you know, compared to whatever you're sort of offhand thoughts
might be about them, and we're continuing to learn more
about them, just a year by year. Yeah. I was
(00:46):
just talking to Rachel a few minutes ago, and uh,
she was not actually aware that a lichen is not
a solitary type of organism, but in fact a composite
organism made of other organisms. Uh. And the I was
trying to come up with an analogy, like, you know,
what do you use using macroscopic life and and the
liking in a way is kind of like if you
(01:07):
had like a human being or a bear or something
sown to a tree and they were just helping each
other out, except it it gets even more complicated than that,
because it wouldn't just be based on some recent research.
It wouldn't just be a bear in a tree, would
be like a bear and a tree and maybe some
other types of vines and things like that. Yeah, it's
(01:27):
it's really one of these um things in nature that defies,
you know, our easy understanding of what life even is,
what does it mean to be a species? Because we've touched,
you know, on the the composite aspects of say even
human biology that we depend on microbes living inside us, etcetera.
(01:49):
But lin Is it's like a more pronounced expression of
this same idea. There's actually a wonderful quote from an
article that we're going to reference in this episode by
a young one of my favorite science writers in the
Atlantic that's about some recent discoveries in like in biology
and ed rights. Quote. When we think about the microbes
(02:10):
that influence the health of humans and other animals, the
algae that provide coral reefs with energy, the mitochondria that
power ourselves, the gut bacteria that allow cows to digest
their food, where the probiotic products that line supermarket shelves,
all of that can be traced to the birth of
symbiosis as a concept, and symbiosis in turn began with lichens. Yeah,
(02:33):
that's that's a great quote from a great article that
will come back to again here. But I understand you
also have a little poetry for us here, Joe. Oh well, yeah, Robert,
you were asking if there were any great poems about lichens,
and I couldn't think of any at first, but I
did come across this actually fantastic poem by Jane Hirshfield
that I'm not going to read in full, but the
title is for the lobaria usnia witches hair map like
(02:57):
in beard, like in ground, like in she old lichen,
which is great because the title itself is almost like
a line from a Walt Whitman poem. But it has
that Walt Whitman spirit. It's very it's very propulsively enthusiastic
about the world. And so in this poem she speaks
about about lichen and she calls them a marriage of
(03:18):
fungi and algae, chemists of the air, changers of nitrogen
unusable into nitrogen usable. And then her last couple of
paragraphs in this poem go like those nameless ones who
kept painting shaping engraving, unseen, unread, unremembered, not caring if
they were no good, if they were past it, rock wolves,
(03:40):
water fans, earth scale, mouse ears, dust, ash of the woods, transformers, unvalued, uncounted,
cell by cell, word by word, making a world they
could live in that's really great. And that that comes
that that that kind of gets into something we'll touch
on later too, about this idea that Liken or some
(04:01):
of the the first settlers of new Lands, you know
that they are, they're the first to emerge on volcanic
soils and so forth. Yeah, And I like how she
compares them to sort of like unknown and unrecognized artists who,
in a way, by by laboring away producing say say
poetry or paintings or things that you know, most people
(04:24):
might never know the names of the authors and the
artists who created these things. But in doing so, they
create a culture, and they make an environment that people
can inhabit, the same way that that Likens sort of
like create an ecosystem within themselves. Yeah. Another thing I
love about this poem is that it reminds me of
college poetry class exercises where our our our teacher and
(04:49):
I remember I had I had a wonderful teacher. Uh.
That would more than one wonderful teacher in college poetry classes.
But I specifically remember my teacher, Maryland Collett would have
us go out and and roam around, find something natural,
and write a poem about it, you know, which I
think is a great exercise uh, you know, in in creativity.
(05:10):
But it also is perfect for liking, because I feel
like I've always found something at least soothing about moss
and and and especially liking uh and indeed something that
that inspires poetry on some level, even if you never
actually right it. It kind of forces a little poetic
energy in the head because I remember as a child
(05:31):
I loved like touching varieties of lichen and moss. You know,
we go out and scramble around on the rocks, and
when you scramble around on the rocks, you're always finding uh,
you know, remarkably new to you alien life, little red
um uh, the little red arachnids uh that are that
are roaming around. And then also you know, different types
of lins, sometimes beautifully colored. Uh. I also love that
(05:54):
lin always had this this kind of miniature world feel
to them, something that was probably compounded by the fact
that my dad kept some miniature railroad dried out liking
that he would use, like facing model tank kit and
that sort of thing, like little dried out likings that
you could put in in a miniature environment and pretend
that they were, you know, shrubbery or even trees. That's
(06:17):
really interesting because it also connects with a very fond
childhood memory that I have, which was that every Christmas,
my family would get out this little decorative tabletop manger scene,
which I have to admit I thought of kind of
like you would you would imagine a G. I. Joe
play set that's got the fortress or the base and
(06:37):
then the action figures that can inhabit it, and I
played with it in the same way I would have
like fights on the roof of the barn and all that.
But so it was a little wooden barn set, and
it had these plastic figurines of of course Mary and
Joseph and the sheep and the and the cows and
the wise men or the magi and the shepherds, and
(06:58):
then the wooden barn set how to kind of lichen
like material all over the roof, I guess for that
rustic Bethlehem feel I don't know if it was actually alive,
but I recall it it felt very lifelike, so it
may have been at some actual dried out lichen or
maybe actually moss like material. I'm not sure. Yeah, this
is interesting because in Christian theology, Jesus is said to
(07:19):
have a triple nature and in in other ways to like.
Even going back to medieval times, there are expressions of
Jesus's having this dual nature of both masculine and uh
and the feminine. But but in many ways, Jesus is
a composite being, so it's perfect that he's in there
amid the lichen. Oh. I like that very much. You
have the like in theology. Now, in terms of just
(07:43):
how widespread lin are, it's it's really amazing. I've read
it estimated that six percent of Earth's land surfaces covered
in liking, and I've also seen this number side it
as seven percent. But either way you shake it, that's
a lot of lichen. I think it's an It's a
type of life that we often think of just occupying
(08:04):
the cracks here and there, the rocks here and there.
We don't think about just how much like in there
is in the world. But one particular researcher who will
will come back too much later in the episode Uh
liking researcher by the name of Jin Peng Wong. In
a in a paper that I'll cite later on, he wrote,
Lichens are everywhere. If you go on a walk in
(08:24):
the city, the rough spots or gray spots you see
on rocks or walls or trees, those are common crust lichens.
On the ground, they sometimes look like chewing gum. And
if you go into a more pristine forest you can
find orange, yellow, and vivid violet colors. Lichens are really pretty.
I think he's kind of selling them short with that
last phrase, but it's hard to follow up. You know,
(08:46):
the poet with the scientists, but I think there's a
lot of poetry with what Wong has to say here. Well. Sure,
and you really do find an amazing aesthetic diversity within
the liking world. For example, there's a type of like
in that figures into a paper that we're going to
talk about later that produces a toxin called vulpinic acid,
(09:09):
But it gives the like in this beautiful yellow green
color that makes me want to eat it, which is
exactly what I should not do. Yeah. Yeah, so some
like in our Our Toxic we'll touch on that as well. Um.
One of the other crazy things about like and is
that you will you will find them growing on every
continent on Earth. And and they're important species that they
(09:30):
grow on soil, rock and bark, but also on buildings
or even barnacles. As James Walton points out in likings
of the Arctic for the National Park Service, they'll even
grow on mountain tops in nunatos, which are the exposed
rock outcrops of ice fields. So they really thrive in
(09:51):
some some otherwise kind of desolate or challenging environments. And
and wherever they are they provide important food, shelter and
nesting material. They're important ecological players for hydrological and mineral cycles.
Oh yeah, Arctic like in stores are specifically what's known
as reindeer like in or sometimes reindeer moss are in
(10:12):
a very important food source for migrating caribou, I think,
especially during the winter. Uh. And the fact that the
word moss comes up, I think it's important to mention
that that lichens are often associated somehow with moss. Many
types of lichen are called types of mosses for example,
reindeer moss, which is a lichen, but in scientific terms
(10:32):
like in and moss are are totally different types of
organisms because moss is one type of organism. Moss is
a plant, whereas lichen are living alliances of fungi and
meshed with tiny photosynthetic organisms for example algae which are plants,
or cyanobacteria, which are bacteria but which make food the
(10:53):
same way plants do by photosynthesis. Yes, sometimes you'll you'll
hear discussion of lichen in terms of lichen ized fungi um,
which which is which is maybe a little more precise
way of thinking about because again it just kind of
bucks traditional understanding that we're not looking at a single species,
we're looking at a composite. Yes, though it's interesting how
(11:15):
certain composites can behave like species in themselves. They have
like certain combinations of what's called the photo bion to
the part of the lichen that that does photosynthesis and
the micro bionto the major fungal components of the lien.
In certain combinations have particular characteristics that can be studied
(11:36):
like the characteristics of an individual species. Yeah, Now, in
terms of the species count, I've seen a number sided
as high as like twenty thousand different known species of lichens.
One of the more recent sources I looked up, though,
puts it more at five hundred. Uh. Either way, a
lot of lichens out there, uh, in the world. Now
(11:58):
we should we should probably back up a little bit
and point out that there was a time when scientists
thought lichen were plants. Later on, as Ed Young points
out in this wonderful Atlantic article titled how a guy
from a Montana trailer park overturned a hundred and fifty
years of biology. Uh. And we'll get to the details
of that headline a bit, but uh, Young points out
(12:18):
that in eighteen sixty eight, a Swiss botanist named Simon
schwinden Or revealed the duel or composite nature of of liking.
But he believed that the fungus had quote head quote
enslaved the alga and this would of course proved not
to quite be the case. Now, a lot of you
(12:38):
are probably listening to this, and you already heard us
mentioned the idea of there being not two, but three
components in a liking. That that might come as a
shock to you because for a long time, uh, post
schwinden er, that's that's what we thought. You probably may
have learned this growing up, and in fact you'll probably
see it in a lot of not so old documentaries.
Um saying, you know, it's it's like a comic book scenario.
(13:01):
It's like a venom and Eddie Brock, you know, the
symbient in the human They come together and then they
become the comic book superhero slash villain. Yeah. I think
this used to be known as the dual hypothesis. There's
two species, they come together, and that's what the liking is.
But it turns out that there there may be more
parties involved, and there often are. Yeah. So for about
(13:21):
a hundred and fifty years, Yeah, we thought lin consists
of a dual mutual relationship between an alga and a fungus.
You get the best of worlds, right. The alga's photo
is the photosynthesizing partner, or the photobiont, and uh, the
fungus is the microbiont, which makes up most of the
bulk of the of what we see. It's composed of
(13:41):
interwoven fungal filaments, and I think typically the idea is
that the fungal elements supplies stuff like structure, physical protection, shelter, minerals,
and water. Whereas the photobiont whether that's something like cyanobacteria
or a plant like an alga, that that provides the sugars.
It turns the sunlight in the carbon dioxide into the
(14:04):
sugars that feed the system. Now there were there ultimately
ended up being problems with this interpretation UM, and of
course part of it would be that we would ultimately
find out it's not just two things. But this was
revealed when say, scientists would would try bringing two identified
varieties of fungus an alga together to try and grow
lin in the lab. Uh, something seemed to be missing.
(14:26):
It was almost as if there was a third component
that was not present that was necessary for this UM
this combination to take place. Yeah, it was not easy
to to incubate lins from their components species in the lab,
at least not as we understood their component species. But
then in two sen so very recently UM a study
(14:50):
was published in the journal Science from researchers at the
University of Montana, working together with colleagues from Austria, Sweden
and Purdue University, and they found that some of the
world's mo common lichen r indeed composed not of two partners,
but three. And in this particular study, they were looking
at two closely related species of lichen in western Montana,
(15:11):
one toxic to mammals and the other not. Yeah, the
toxic one is the one that makes that poison I
referred to earlier vulpinic acid. The one that makes the
vulpinic acid is that gorgeous yellow green color, and the
one that doesn't make it as kind of a brown color. Apparently,
lichens containing vulpinic acid have at least allegedly been used
to poison wolves in the past. So you might bait
(15:33):
some meat with vulpinic acid lichen in order to to
kill the wolves. I guess if you were trying to
do that. Uh, don't kill wolves, folks. Yeah, but it
is interesting. We were able to work some uh some
lichens into our lichn episode here. Oh I see as
in Rise of the Likings. Oh yeah, I gotta share.
Before we recorded this, I was trying to google horror
(15:54):
movies about lichens to see if there were any like
spelling in the correct way l I C H E N.
But it was just bringing up underworld verse stuff, which
apparently is full of l y c a nds that
are that are their werewolf buddies. Yeah, Google, at times
and other search engines refused to believe that you're you're
actually searching for likings, which I think is a bit presumptuous.
(16:17):
I looked around a little bit too, and I could
not find any liking based horror films. But this is interesting.
Um the film or film adaptations of the Day of
the Triffids uh the novel by John Wyndham. A lot
of people probably know this one because there's a There's
their Killer plants in this book and in the movies
(16:38):
that are based on it. But Wyndham also wrote a
book I was reading. I have not read this, but
he has a nineteen sixty book titled Trouble with Liking,
and it's about a discovery that some sort of unusual
strain of lichen pink can be used to uh slow
down the aging process and enable people to live for centuries.
And then here's apparently a lot of speculation in the
(17:00):
novel about how this would affect society. Well, that's actually
interesting because there is a lot of research into secondary
metabolites produced by lichens as possible uh as possible candidates
for use in biotechnology and medicine. That you know, lichens
produce all kinds of interesting compounds that are of of
(17:21):
great interest too. I think, well, what's the term that
might be called? Like bioprospectors. Yeah, it's also my understanding
there have been some studies of certainly post in the
period after this book came out, that have looked at
potential anti aging um drugs that could be made from lichens. So,
I don't know, interesting topic one. Perhaps we'll have to
(17:42):
come back to in a future episode if everybody gets
liking fever from this one. Well, in fact, even a
minute ago, I was talking about that poison vulpinic acid
that is made by one of the likings that's in
the study, and even volpinic acid itself has been the
subject of a study about treating a throws sclerosis. I think, yeah, so, uh,
let's let's get back to those two likings from the study.
(18:04):
Though again, one of them is um uh is toxic
to mammals. The other is not. But here's the thing.
Previous DNA studies had ruled that the two species were
actually identical, and it was unknown why one was toxic
and the other was not. And this was seen another
liking as well, with other cases in which two types
of liking had the exact same symbiotic partners but differed
(18:28):
wildly in appearance in chemistry. So what was up? So
inter then University of Montana postdoctoral researcher Toby Spreebel, who
is now I believe with the University of Alberta, I think,
but he was the research lead on the study and
it was apparently, you know, quite a ground breaking study, uh,
(18:48):
you know, using a lot of new technology and teaming
up with it wasn't just a Spreebel here, he was
teaming up with a very talented team including u M
University of Montana microbiologist John mcmccutcheon, who had worked with
a lot of insects indiosis studies in the past. All right,
so how do we get to that trifold nature? Okay,
So what they did is they did RNA analysis and
(19:10):
found two fungal species in the test lichens, and they
found that the toxic liking contained more of it the
secondary fungus and this would be the third component of
the of the lichen turned out to actually be a yeast. Yeah,
so the original assumption was that these likings were composed
of a partnership between the photo byant and then the
(19:31):
micro bion was believed to be entirely represented by this
group called the asco my seats, which is a certain
type of fungus. But instead what they found is there
were a bunch of other fungus genes being activated that
belonged to a group known as the basidio my seats. Yeah,
and and so one the crazy thing here is, Okay,
you hear about this and you think, okay, well, they
found a really interesting pair of lichen in Montana. Well
(19:56):
it doesn't stop there, though, because they started testing lichen
from around the world, and I mean from around the world,
including like Antarcticum varieties, and they revealed that this was
not an isolated phenomenon and in the words of McCutcheon,
it was all quote hiding in plain sight for more
than a hundred years. Uh so, uh, it really did
(20:16):
shake up everything we thought we knew about liking. Even
ruined some perfectly good poems. Oh yeah, because the poem well,
I mean, I don't know if the poem is totally ruined,
but yeah, the Jane hirsh Field poem does sort of
envision the liking as a partnership between two and in fact,
it seems now that many lichens are a partnership between
(20:37):
at least two and include other elements as well, for example,
this yeast. And so when you look down at the
micro structure of a lichen, what's often going on is
that it's kind of loaf shaped, and then in the
interior of the loaf you've got a lot of fungal fibers,
and then on the exterior of the loaf you've got
this sort of crust, the structural cortex that has of
(21:00):
course the photo bion element in there, which is doing
the photosynthesis, But then it also has these yeast elements
in the crust, and so what are they doing there?
What what purpose does the yeast serve? Well, I think
in a lot of cases it's not entirely clear yet. Yeah,
based on certainly based on the writings of the time,
and I think this holds true to today, is that
(21:21):
it's still kind of an open question what this These
new third partners are necessarily doing a lot of research
is ongoing and is still yet to be done to
figure out exactly how the lin really works. In light
of this revelation in the world's just almost always more
complicated than you thought. Yeah. Yeah, you push through one
door and then you just find out that there's another
(21:43):
one that was just just a little uh further away
than you were able to glimpse. Yeah, well, should we
take a break and then come back to talk about
some like in history. Let's do it. Thank thank alright,
we're back. So, uh, you know, an important question to
ask is how long have have lins been around? Well,
(22:04):
it's a it's a it's a more difficult question to
answer than you might think because certainly the oldest for
sure fossil likened data goes back to the early Devonian
um uh period. This would have been about four hundred
million years ago, and we have this evidence from a
sedimentary deposit called the Rheiny Church, unearthed near Aberdeen, Scotland. Now,
(22:28):
to call back to a past episode, uh, the Devonian
was the age of prototax I d s and other
strange land flora. So this is one of those those
periods in uh, in Earth's history where it's it's a
it's an interesting exercise to just try to imagine yourself
standing on those strange soils well, yeah, the Devonian was
the age of fishes, but I think it was also
(22:49):
the time when we think that the the dry land
of Earth was first significantly populated by by plant life,
right right, right, So you know that, so we have
fossil evidence of lin from this time, and you know
that the question is okay, well when did liken emerge? Now?
One thing to stress about all of this is that
fossil record of lin is not all that compelling. Most
(23:11):
liken dominated habitats such as tundras, deserts, mountaintops, they don't
produce a lot of fossils. And of course we also
have to remember that the fossil record itself is inherently incomplete.
Not everything fossilizes, and and and as it turns out,
like in are are less prone to fossilization. Yeah, the
fossil record is not a clear indication of what existed.
(23:34):
It often is biased in favor of what kinds of
things get fossilized easily and what you know, there are
certain steps that you have to go through in order
to get fossilized. You have to often get buried quickly
after death in certain types of soil and chemical soil conditions,
so it's it's a finicky process. Yeah. Now, there there
are some fossils from between two point two and two
(23:56):
point seven billion years ago that have at least in
the path asked been interpreted by some as being likenised organisms.
But it's nothing that everyone agrees on. So um, so
we can't really we can't really dated back that far. Um.
But like can have certainly existed for hundreds of millions
of years. But we used to think that they were
even older, that they were perhaps even the earliest land organisms.
(24:21):
And this this has long been the conventional wisdom on lins,
and it matches up with how they are frequently observed
to behave on our own world today. Um lichn is
often documented as an early colonizer of New Land. And
again they're capable of popping up in some really rugged
conditions again you know, mountain tops, bits of of rock
poking out of the frost, that sort of thing. Um.
(24:44):
So you know, it seems to match up with what
we see. Uh. One example, I came across to give
like some some some sort of um, you know, human
level um. Uh, you know time stamps. The volcanic island
of Certaincy emerged in nineteen sixty three, and by nineteen
seventy lichens were found growing there. So I think that provides,
(25:05):
you know, a sort of a rough timeline for how
this sort of thing might occur, not in the archaic since,
but in you know, in our modern world, right, because
at least in the modern world you already have liken
symbiosis that exists. It doesn't have to evolve a new
it just has to colonize the land. But it does
colonize the land quite well. Yeah. Now, the most recent evidence,
(25:26):
interestingly enough, um suggests that that this idea of lichen
as the first colonizer of of New Earth, Uh, that
this is not quite the case. I was reading a
wonderful two thousand nineteen New York Times article by Joanna
Klein on this, uh and uh. Basically in the idea
here is that likns may have made their way onto
(25:47):
land some one d million years after ferns and other
vascular plants. And interestingly enough, this actually matches up, uh,
you know, to the extent that we can compare these
two things with the data from certain cy that Volcanic Island,
because vascular plants actually popped up there by nineteen sixty five,
that's just two years after it emerged, and mosses by
(26:09):
nineteen sixty seven. But but to be clear, we do
observe lichens filling the role of first settlers in environment.
So it's it's not like it doesn't occur, um but uh.
But anyway, based on the more recent evidence, it seems
that that lichens would have followed ferns and other vascular
plants on to the primordial Earth. Yeah, and it seems
(26:32):
especially apt to happen in certain types of extreme environments
where lichens are more well adapted than plants would be
on their own, for example Arctic tundra. Yeah. Like one
way of looking at it, and this was certainly part
of the older interpretation is that lichen would grow where
plants could not, and they would make the environment more
hospitable than for vascular plants to move in. Okay, so
(26:54):
that was the old theory, But maybe that might not
always be the case. That's right, because in two thousand
nineteen you had the study um uh from Nelson at
all published in Geobiology that pushes the evolution of lichn
to two and fifty million years ago. But they also
argue that different fun guy developed their alga hugging habits
independently and didn't inherit it from one main ancestor. But
(27:18):
it still remains a lot to be done in the
genomic study of likn. But but still it does seem
to point towards a a version of history in which
lin follows the vascular plants follows the ferns. Right now,
this is all kind of a set up to the
main question I had in the main paper that really
caught my interest here, revolving around this question, how did
(27:40):
lichn fair when the dinosaurs died sixty six million years
ago in the Kati extinction event. This is a really
interesting question because we've discussed on the show before the
role of fung gui by themselves in the aftermath of
the kat extinction. Specifically, the hypothesis us that fungi may
(28:01):
have played a role in the evolving primacy of mammals
in the food chain after the KPg extinction. Because if
you you have this period where um where much of
the sunlight is being blocked out, and so you have
this earth that's just full of dead, rotting plant and
animal matter, what's doing really well in a place full
of dead rotting animal and plant matter. It's fungus, right.
(28:24):
Fungus is the decomposer of the Earth. And so if
you've got planet fungus in the wake of this asteroid
impact or combination of asteroid impacts and volcanic eruptions, what
survives well in the presence of an aggressive fungus dominated biosphere. Well,
apparently mammals in their warm blood do a lot better
(28:45):
at protecting their bodies from fungal infection than say, cold
blooded reptiles do. Yeah. And another part of that too
is not only is the post Katie extinction world a
world full of dead things, it's also a world in
which the sky is darkened by the ash clouds, although
of what was probably a near Earth object impact, right,
(29:08):
I guess that that's what causes the dead things to
begin with. So I think that the commonly assumed cascade
is there's impact that darkens the skies, which which limits
the amount of sunlight available to the primary producers, such
as plants, so they all die off. The animals that
eat the plants can't get enough food, so they start
to die off. The animals that those animals can't get
(29:28):
enough food, so they start to die off. And it's
this trophic cascade of death creating a just you know,
an amazing buffet for the fungus of the earth. So
that this particular paper that looked into this two nineteen
study again just really driving home how much of our
like in like really exciting like in work is happening
right now. And and as ill as I'll touch on
(29:50):
two like this is a study that couldn't have taken
place just ten years ago. But this study was from
the Field Museum, um Cassette, Start University of him Young University,
and Academia Seneca, and they looked into this question that
the lead author was Jim Peng Wong, who I referenced earlier,
read a quote from him, a former postdoctoral researcher at
the Field Museum in Chicago. And so the idea here is, yeah,
(30:13):
like we've been discussing, Katie, extinction of then occurs wipes
out the non avian dinosaurs, but also plenty of other
organisms as well, a lot of early birds. Um that
they have that ash rising up into the sky blocking
out the sun. So photosynthetic organisms also suffered. Plant life
was devastated on Earth. So Huong was curious about the
lichen Uh He and his team. They suspected that lichn
(30:36):
would have suffered as well given their relationship with the Sun. Again,
that's part of lichens whole thing is that they have
the fungal element, but then they have the the alga
that that are also that are I mean, that are
capable of photosynthesis. But it comes back to the dual
nature of lichen, right because there, you know, there's the
photosynthetic aspect of of the of the life forms that
are good that would presumably suffer in this world. But
(30:58):
then there's the fungal ask becks that that might thrive. Um.
So anyway, they decided to look into this. Uh, we've
already touched on the fact that fossil records show an
increase in fungal smores. At this time, we know that
fungus was was getting to run amuck post KT extinction event.
This is planet mold. You have planet mold. But when
(31:21):
it comes to like and again like in fossils are
not common enough to really prop up a study like this,
So most of this was based on modern Like in DNA,
it involved identifying the mutation rate in species, determining common ancestors,
and they used to program to sort through these large
molecular data sets, and this is what Huong points out
is being just something that wouldn't have been possible ten
(31:43):
years ago. And all of this is also backed up
by what fossil evidence we do have and um and
this was used to see, okay, when are we when
are we observing branching occurring among the liking and at
least for some like in families. The results of all
this point to a boom in liken populations after sixty
(32:03):
six million years ago, So that's very interesting. Was that
we have genetic evidence or genomic evidence of what was
going on with with liken species diversity in general, but
we don't necessarily know all the reasons why. And there
would be some lingering questions, right like if if the
if plant life is suffering because of decreased access to
the sun and so forth, wouldn't likens also be suffering
(32:25):
because they're also not getting the you know, the sunlight
for the photosynthesis that makes their carbohydrates. But then of
course you've got this fungus component in a world where
fungus is doing well. So yeah, it makes you wonder
about the mechanisms at play. But it looks like at
least some species were doing really well and diversifying at
this time right now. Now, to be clear, some liken
(32:47):
definitely went extinct, and other lien seemed you know, they
seemed to be doing okay. You know, they weren't thriving,
but they weren't perishing. But interestingly enough, you did have
these families that thrived. Um now at Long points to
the fact that some lichens grow sophisticated three D structures
like plant leaves, and therefore it could have been these species,
(33:08):
he argues, that filled the niches of the plants that
died out. So you have widespread, uh plant devastation that
that creates an opportunity for certain savvy, composite organisms to
rise up and fill the void. That's really interesting. So
maybe after the dust clears, whatever's left might involve a
lot of lichens that suddenly have new opportunities to say,
(33:30):
access sunlight, whereas previously there would have been plant cover
blocking them or something. Yeah, yeah, I think so. But again,
like you said, this is an area of very new
stag nineteen. A lot of work still remains here, but
it is it is interesting. You have to think back
on this post extinction age and imagining, you know, at
its own pace, the lichen uh taking over alongside the mold. Yeah. Alright,
(33:54):
on that note, we're going to take a quick break,
but we'll be right back with more liking. Alright, we're back.
So to finish out here today, I wanted to talk
briefly about a paper that I will admit caught my attention,
mainly just because it's brand new. It came out this summer,
and I was looking for recent like in research, and
(34:15):
also because of a punny title. But it actually turned
out to be very weird and interesting. So the paper
I want to talk about was published in the journals
Symbiosis in July by Lucia Mugia, Polano's Allar Armando Azua
Bustos and Carlos Gonzales Silva, Martin Grube and Nina Gunde Simmerman,
(34:36):
and it is called The Beauty and the Yeast. Can
the microalgae Donaliella form a borderline lichen with Jortea vernecki
i uh so? The authors here point out that, of course,
symbiotic relationships often allow organisms to survive in environments where
they wouldn't be able to survive and proliferate at least
(34:57):
not as well if they were on their own. And
lichens are of course an example of this. You'll find
like in thriving in environments where the microbiant and the
photobiont alone would face extreme challenges. But the question is
how do these relationships evolve in the first place. What
gets these organisms working together and becoming a composite, becoming uh,
(35:19):
just a partner within a symbiosis. The author's site previous
studies showing that like and thali meaning the physical structure
of the like and go back to the Lower Devonian
as we were talking about earlier. But there's still a
lot we don't know about how these alliances between organisms
are formed in their earliest stages. They're surely interacting and
(35:39):
forming relationships before they're actually building bodies together. And one
place where we can look for clues about the early
stages of this evolutionary process is in what are known
as a borderline likens, which they define as quote species
associations showing a high degree of specialization, but without the
form a shin of well differentiated fungal layers characteristic of
(36:03):
true lins. And one of the organisms that they're studying
here really melted my brain. I love this. Uh. It
was first described in a study from two thousand ten
by Armando Azua Bustos see Gonzales, Silva, el solace, Ari Palma,
and R. Vicuna. And this was a study published in
(36:24):
the journal Extreme of Files in two thousand ten. So
the authors of the study describe a newly discovered species
of single celled alga in the genus Dunaliella. Now normally
Dunaliella is a marine algae. They're they're tolerant of hyper
saline conditions, so you salt them like a slug. They
don't really care. Uh. The scientific term for the ability
(36:47):
to live in really salty conditions is halo tolerance. By
the way, don't salt a slug, You'll just make a
nath and you'll feel bad afterwards. Oh yeah, why why
would you do that? How would you feel if a
slug salted you? Yeah? Uh So. Donaliella is a primary
food source for a lot of filter feeders of plankton
in the ocean. Uh, and a few species can actually
(37:09):
be found in freshwater sources, but this genus has always
been known as a water dwelling class of organisms. You
find them in the water, and almost always in very
salty water. Well. The study in two thousand ten discovered
an exception here. Researchers described a species of Dunaliella found
on the walls of a cave in the Atacama Desert
(37:32):
of Chile. So one of the driest places in the world.
How would the alga be surviving in a desert cave?
And at this point, I just want to read a
quote from the paper. Quote. On further inspection, we noticed
that it grows upon spider webs attached to the walls
of the entrance twilight transition zone of the cave. This
(37:55):
peculiar growth habitat suggests that this Dunaliella species uses air
moisture condensing on the spider web silk threads as a
source of water for doing photosynthesis in the driest desert
of the world. This process of adaptation recapitulates the transition
that allowed land colonization by primitive plants and shows an
(38:19):
unexpected way of expansion of the life habitability range by
a microbial species. So whoe, I mean? So many things
interesting about this. So you're you're talking about a plant,
an alga that normally lives in the water. Now living
on land. Of course it needs sunlight to survive, but
(38:41):
it lives in a cave. So how is this going
on while it's living on silk from spider web threads,
which you know, collects moisture from the fog in the air,
and then it stays in the twilight transition zone of
the cave so it can still get some sunlight in
order to do photosynthesis. This is a This is a
(39:03):
real cliffhanger of an organism. Yeah, yeah, I just I mean,
you know, most of us wouldn't think of, you know,
spider webs in the twilight realm of a cave. Uh.
And and and think to ourselves that's a that's a
great place for some uh you know, of photosyn synthetic
organism to thrive. It's yeah, it's so strange. Yeah, but
(39:25):
that's nature on the spider webs. So I love this.
And anyway, this species is now known as Dunaliella at
a commensus. And to come back to this paper in symbiosis,
the authors note something else about this species of alga.
It has been observed cuddling up to some fungus, specifically
(39:45):
another hallow tolerant organism, a fungus A kind of black
yeast called Hortatia vernecki i. So you would normally when
you look at these in these little dew drops of
water that are forming from the silk of a spy
fider web in this cave, you will find small colonies
of algae of this species at at a commensus in
(40:09):
which you will find embedded cells of this black yeast verneckii.
And as far as I can tell, there was no
previous evidence that these species were in a symbiotic relationship.
That they just appear to be huddling together, and finding
organisms in proximity to one another is not necessarily a
(40:29):
sign that they're symbiotic. You can think of examples, you know,
where you might find organisms together but not symbiotic in nature.
I think, for example, about different animal species that you
might find gathering around a savannah water source to drink.
So if you have gazelles and elephants nearby each other
drinking water, they're not necessarily in a symbiotic relationship with
(40:50):
each other. They just happen to be side by side
accessing a common resource. And so the question these authors
were looking into is, well, can we find any evidence
that these species are actually in a mutualism that they're
providing benefits to one another, and unfortunately the study encountered
problems where they were unable to get the algae to
(41:12):
grow properly in vitro. They actually tried a couple of
different algae, both at A Commensis and then another one
known as de Selena, which they note as a common
inhabitant of saltern brindes and salterns are pools of sea
water that can evaporate and leave crystal salt behind. But anyway,
so they had these these methodological problems trying to get
(41:33):
the algae to grow in the lab, and they discussed
several possible reasons for this, including the possibility that the
washing process of preparing the algae for in vitro incubation
may have removed some kind of vital environmental nutrient, or
in keeping with the findings that we were talking about
earlier from spree Bill and others, it may possibly have
(41:56):
removed some other crucial but yet unidentified microorganism partner. So
we still don't know if these organisms are involved in
what could be called a borderline like in relationship or not.
The experiment was not able to establish evidence of any
mutual benefit provided. But I do want to say I
always respect reading research that doesn't come to a conclusion
(42:18):
about its central question, but still publishes its findings, because,
for example, discussion of the methodological problems they encountered could
be useful for other researchers who were trying to study
the same thing. Yeah. Absolutely, And I guess it's easy
to lose sight of the importance of that, especially in
a sort of headline driven science consumption, Right you want
(42:39):
that especially We've already touched on some some some studies
that definitely hit that chord totally. So the question remains
about these species in particular. But I think this this
is one fascinating picture of how the symbiotic relationships that
create like and could potentially first evolve. You have two
tiny organisms clinging to one another for drops of fog
(43:02):
do collecting in a spider's web in a cave against
the water starved desert, and perhaps eventually in these harsh
conditions they could come to appreciate what they can do
for one another in an evolutionary sense, But we we
don't always know how it happens. And that that's hammered
home by another quote that was cited in ed Young's
article that was from a researcher from the University of
(43:25):
Exeter named Nick Talbot who's talking about lin and Talbot says, quote,
if the right combination meet together on a rock or twig,
then a lin will form and this will result in
a large and complex plant like organism that we see
on trees and rocks very commonly. The mechanism by which
the symbiotic association occurs is completely unknown and remains a
(43:49):
real mystery. I love it. I mean, so it happens
in nature all the time, we see it all over
the world, but it's it seems to be kind of
scattershot as to whether we can recreate a in lab
conditions or what all is needed to make the relationship work. Yeah,
it's it's it's such a fascinating topic again. Um, liking
(44:10):
are just so much more mysterious, uh and and been
beautiful and complex, and we often give them credit. Um.
I know during this trying time, those of us who
do have access to nature have you know, have probably
been taking more nature walks. I know, just based on
my own famili's activities and on various friends that I uh,
(44:32):
you know, say follow on on Instagram. I know I've
noticed a lot of people exploring their their natural world
a little bit more, getting into perhaps, uh you know,
the chronicling mushrooms in their area. Mushroom hunting can be
a great deal of fun. But liken hunting uh also
something I think it's on the table right now. Go out,
Uh look for the liking. Um, you know, observe the
(44:54):
like and heck, heck, if you want to take some
photos of liking and share them with us, uh, please
do so. We'll we'll tell you where you can email
us here in a bit. But also we have the
we have the old Facebook group, the discussion module, the
stuff to Wear your Mind discussion module. That's it seems
like a perfect place to drop some lik in photos. Yeah.
Also frankenstein up your own like and see if you
can do it? Can you incubate get some algae and
(45:16):
some fungus together and just throw them into the mix.
See what happens. Yeah, that's a good beginner level, like
an experiment for your your quarantine day. It probably won't work,
but you know, it's always worth a try. All right, Well,
there you have it. Um as always, UM, you know,
you can find our podcast wherever you get your podcasts. Uh.
And that goes without saying right wherever that happens to be.
(45:38):
If there's a way to rate us, to review us,
to give us a nice you know, smattering of stars. Uh,
you appreciate that helps the show out allegedly. Um. But yeah,
if you just have some wonderful liking experiences, some li
in sightings, or even better, if you have a liking expertise.
(45:59):
Are you are are you are you a liking hunter,
an amateur like and hunter? Are you yourself a lichnologist?
Well then we would love to hear from you. Of course.
Now we always want to say a huge thank you
to our excellent audio producer Seth Nicholas Johnson. But if
you do want to get in touch with us, you
can email us as always at contact at stuff to
Blow your Mind dot com. Stuff to Blow Your Mind
(46:29):
is production of I Heart Radio. For more podcasts for
My Heart Radio, visit the iHeart Radio app, Apple Podcasts,
or wherever you're listening to your favorite shows,
Welcome to Stuff to Blow Your Mind, production of by
Heart Radio. Hey you welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick. And
today we're gonna be talking about lichens. That's right. I'm
excited for this one because the lichen are the type
(00:25):
of life form that are are easy to take for granted,
but at the same time are in more places than
you think, and are of course far more complicated and mysterious. Uh,
you know, compared to whatever you're sort of offhand thoughts
might be about them, and we're continuing to learn more
about them, just a year by year. Yeah. I was
(00:46):
just talking to Rachel a few minutes ago, and uh,
she was not actually aware that a lichen is not
a solitary type of organism, but in fact a composite
organism made of other organisms. Uh. And the I was
trying to come up with an analogy, like, you know,
what do you use using macroscopic life and and the
liking in a way is kind of like if you
(01:07):
had like a human being or a bear or something
sown to a tree and they were just helping each
other out, except it it gets even more complicated than that,
because it wouldn't just be based on some recent research.
It wouldn't just be a bear in a tree, would
be like a bear and a tree and maybe some
other types of vines and things like that. Yeah, it's
(01:27):
it's really one of these um things in nature that defies,
you know, our easy understanding of what life even is,
what does it mean to be a species? Because we've touched,
you know, on the the composite aspects of say even
human biology that we depend on microbes living inside us, etcetera.
(01:49):
But lin Is it's like a more pronounced expression of
this same idea. There's actually a wonderful quote from an
article that we're going to reference in this episode by
a young one of my favorite science writers in the
Atlantic that's about some recent discoveries in like in biology
and ed rights. Quote. When we think about the microbes
(02:10):
that influence the health of humans and other animals, the
algae that provide coral reefs with energy, the mitochondria that
power ourselves, the gut bacteria that allow cows to digest
their food, where the probiotic products that line supermarket shelves,
all of that can be traced to the birth of
symbiosis as a concept, and symbiosis in turn began with lichens. Yeah,
(02:33):
that's that's a great quote from a great article that
will come back to again here. But I understand you
also have a little poetry for us here, Joe. Oh well, yeah, Robert,
you were asking if there were any great poems about lichens,
and I couldn't think of any at first, but I
did come across this actually fantastic poem by Jane Hirshfield
that I'm not going to read in full, but the
title is for the lobaria usnia witches hair map like
(02:57):
in beard, like in ground, like in she old lichen,
which is great because the title itself is almost like
a line from a Walt Whitman poem. But it has
that Walt Whitman spirit. It's very it's very propulsively enthusiastic
about the world. And so in this poem she speaks
about about lichen and she calls them a marriage of
(03:18):
fungi and algae, chemists of the air, changers of nitrogen
unusable into nitrogen usable. And then her last couple of
paragraphs in this poem go like those nameless ones who
kept painting shaping engraving, unseen, unread, unremembered, not caring if
they were no good, if they were past it, rock wolves,
(03:40):
water fans, earth scale, mouse ears, dust, ash of the woods, transformers, unvalued, uncounted,
cell by cell, word by word, making a world they
could live in that's really great. And that that comes
that that that kind of gets into something we'll touch
on later too, about this idea that Liken or some
(04:01):
of the the first settlers of new Lands, you know
that they are, they're the first to emerge on volcanic
soils and so forth. Yeah, And I like how she
compares them to sort of like unknown and unrecognized artists who,
in a way, by by laboring away producing say say
poetry or paintings or things that you know, most people
(04:24):
might never know the names of the authors and the
artists who created these things. But in doing so, they
create a culture, and they make an environment that people
can inhabit, the same way that that Likens sort of
like create an ecosystem within themselves. Yeah. Another thing I
love about this poem is that it reminds me of
college poetry class exercises where our our our teacher and
(04:49):
I remember I had I had a wonderful teacher. Uh.
That would more than one wonderful teacher in college poetry classes.
But I specifically remember my teacher, Maryland Collett would have
us go out and and roam around, find something natural,
and write a poem about it, you know, which I
think is a great exercise uh, you know, in in creativity.
(05:10):
But it also is perfect for liking, because I feel
like I've always found something at least soothing about moss
and and and especially liking uh and indeed something that
that inspires poetry on some level, even if you never
actually right it. It kind of forces a little poetic
energy in the head because I remember as a child
(05:31):
I loved like touching varieties of lichen and moss. You know,
we go out and scramble around on the rocks, and
when you scramble around on the rocks, you're always finding uh,
you know, remarkably new to you alien life, little red
um uh, the little red arachnids uh that are that
are roaming around. And then also you know, different types
of lins, sometimes beautifully colored. Uh. I also love that
(05:54):
lin always had this this kind of miniature world feel
to them, something that was probably compounded by the fact
that my dad kept some miniature railroad dried out liking
that he would use, like facing model tank kit and
that sort of thing, like little dried out likings that
you could put in in a miniature environment and pretend
that they were, you know, shrubbery or even trees. That's
(06:17):
really interesting because it also connects with a very fond
childhood memory that I have, which was that every Christmas,
my family would get out this little decorative tabletop manger scene,
which I have to admit I thought of kind of
like you would you would imagine a G. I. Joe
play set that's got the fortress or the base and
(06:37):
then the action figures that can inhabit it, and I
played with it in the same way I would have
like fights on the roof of the barn and all that.
But so it was a little wooden barn set, and
it had these plastic figurines of of course Mary and
Joseph and the sheep and the and the cows and
the wise men or the magi and the shepherds, and
(06:58):
then the wooden barn set how to kind of lichen
like material all over the roof, I guess for that
rustic Bethlehem feel I don't know if it was actually alive,
but I recall it it felt very lifelike, so it
may have been at some actual dried out lichen or
maybe actually moss like material. I'm not sure. Yeah, this
is interesting because in Christian theology, Jesus is said to
(07:19):
have a triple nature and in in other ways to like.
Even going back to medieval times, there are expressions of
Jesus's having this dual nature of both masculine and uh
and the feminine. But but in many ways, Jesus is
a composite being, so it's perfect that he's in there
amid the lichen. Oh. I like that very much. You
have the like in theology. Now, in terms of just
(07:43):
how widespread lin are, it's it's really amazing. I've read
it estimated that six percent of Earth's land surfaces covered
in liking, and I've also seen this number side it
as seven percent. But either way you shake it, that's
a lot of lichen. I think it's an It's a
type of life that we often think of just occupying
(08:04):
the cracks here and there, the rocks here and there.
We don't think about just how much like in there
is in the world. But one particular researcher who will
will come back too much later in the episode Uh
liking researcher by the name of Jin Peng Wong. In
a in a paper that I'll cite later on, he wrote,
Lichens are everywhere. If you go on a walk in
(08:24):
the city, the rough spots or gray spots you see
on rocks or walls or trees, those are common crust lichens.
On the ground, they sometimes look like chewing gum. And
if you go into a more pristine forest you can
find orange, yellow, and vivid violet colors. Lichens are really pretty.
I think he's kind of selling them short with that
last phrase, but it's hard to follow up. You know,
(08:46):
the poet with the scientists, but I think there's a
lot of poetry with what Wong has to say here. Well. Sure,
and you really do find an amazing aesthetic diversity within
the liking world. For example, there's a type of like
in that figures into a paper that we're going to
talk about later that produces a toxin called vulpinic acid,
(09:09):
But it gives the like in this beautiful yellow green
color that makes me want to eat it, which is
exactly what I should not do. Yeah. Yeah, so some
like in our Our Toxic we'll touch on that as well. Um.
One of the other crazy things about like and is
that you will you will find them growing on every
continent on Earth. And and they're important species that they
(09:30):
grow on soil, rock and bark, but also on buildings
or even barnacles. As James Walton points out in likings
of the Arctic for the National Park Service, they'll even
grow on mountain tops in nunatos, which are the exposed
rock outcrops of ice fields. So they really thrive in
(09:51):
some some otherwise kind of desolate or challenging environments. And
and wherever they are they provide important food, shelter and
nesting material. They're important ecological players for hydrological and mineral cycles.
Oh yeah, Arctic like in stores are specifically what's known
as reindeer like in or sometimes reindeer moss are in
(10:12):
a very important food source for migrating caribou, I think,
especially during the winter. Uh. And the fact that the
word moss comes up, I think it's important to mention
that that lichens are often associated somehow with moss. Many
types of lichen are called types of mosses for example,
reindeer moss, which is a lichen, but in scientific terms
(10:32):
like in and moss are are totally different types of
organisms because moss is one type of organism. Moss is
a plant, whereas lichen are living alliances of fungi and
meshed with tiny photosynthetic organisms for example algae which are plants,
or cyanobacteria, which are bacteria but which make food the
(10:53):
same way plants do by photosynthesis. Yes, sometimes you'll you'll
hear discussion of lichen in terms of lichen ized fungi um,
which which is which is maybe a little more precise
way of thinking about because again it just kind of
bucks traditional understanding that we're not looking at a single species,
we're looking at a composite. Yes, though it's interesting how
(11:15):
certain composites can behave like species in themselves. They have
like certain combinations of what's called the photo bion to
the part of the lichen that that does photosynthesis and
the micro bionto the major fungal components of the lien.
In certain combinations have particular characteristics that can be studied
(11:36):
like the characteristics of an individual species. Yeah, Now, in
terms of the species count, I've seen a number sided
as high as like twenty thousand different known species of lichens.
One of the more recent sources I looked up, though,
puts it more at five hundred. Uh. Either way, a
lot of lichens out there, uh, in the world. Now
(11:58):
we should we should probably back up a little bit
and point out that there was a time when scientists
thought lichen were plants. Later on, as Ed Young points
out in this wonderful Atlantic article titled how a guy
from a Montana trailer park overturned a hundred and fifty
years of biology. Uh. And we'll get to the details
of that headline a bit, but uh, Young points out
(12:18):
that in eighteen sixty eight, a Swiss botanist named Simon
schwinden Or revealed the duel or composite nature of of liking.
But he believed that the fungus had quote head quote
enslaved the alga and this would of course proved not
to quite be the case. Now, a lot of you
(12:38):
are probably listening to this, and you already heard us
mentioned the idea of there being not two, but three
components in a liking. That that might come as a
shock to you because for a long time, uh, post
schwinden er, that's that's what we thought. You probably may
have learned this growing up, and in fact you'll probably
see it in a lot of not so old documentaries.
Um saying, you know, it's it's like a comic book scenario.
(13:01):
It's like a venom and Eddie Brock, you know, the
symbient in the human They come together and then they
become the comic book superhero slash villain. Yeah. I think
this used to be known as the dual hypothesis. There's
two species, they come together, and that's what the liking is.
But it turns out that there there may be more
parties involved, and there often are. Yeah. So for about
(13:21):
a hundred and fifty years, Yeah, we thought lin consists
of a dual mutual relationship between an alga and a fungus.
You get the best of worlds, right. The alga's photo
is the photosynthesizing partner, or the photobiont, and uh, the
fungus is the microbiont, which makes up most of the
bulk of the of what we see. It's composed of
(13:41):
interwoven fungal filaments, and I think typically the idea is
that the fungal elements supplies stuff like structure, physical protection, shelter, minerals,
and water. Whereas the photobiont whether that's something like cyanobacteria
or a plant like an alga, that that provides the sugars.
It turns the sunlight in the carbon dioxide into the
(14:04):
sugars that feed the system. Now there were there ultimately
ended up being problems with this interpretation UM, and of
course part of it would be that we would ultimately
find out it's not just two things. But this was
revealed when say, scientists would would try bringing two identified
varieties of fungus an alga together to try and grow
lin in the lab. Uh, something seemed to be missing.
(14:26):
It was almost as if there was a third component
that was not present that was necessary for this UM
this combination to take place. Yeah, it was not easy
to to incubate lins from their components species in the lab,
at least not as we understood their component species. But
then in two sen so very recently UM a study
(14:50):
was published in the journal Science from researchers at the
University of Montana, working together with colleagues from Austria, Sweden
and Purdue University, and they found that some of the
world's mo common lichen r indeed composed not of two partners,
but three. And in this particular study, they were looking
at two closely related species of lichen in western Montana,
(15:11):
one toxic to mammals and the other not. Yeah, the
toxic one is the one that makes that poison I
referred to earlier vulpinic acid. The one that makes the
vulpinic acid is that gorgeous yellow green color, and the
one that doesn't make it as kind of a brown color. Apparently,
lichens containing vulpinic acid have at least allegedly been used
to poison wolves in the past. So you might bait
(15:33):
some meat with vulpinic acid lichen in order to to
kill the wolves. I guess if you were trying to
do that. Uh, don't kill wolves, folks. Yeah, but it
is interesting. We were able to work some uh some
lichens into our lichn episode here. Oh I see as
in Rise of the Likings. Oh yeah, I gotta share.
Before we recorded this, I was trying to google horror
(15:54):
movies about lichens to see if there were any like
spelling in the correct way l I C H E N.
But it was just bringing up underworld verse stuff, which
apparently is full of l y c a nds that
are that are their werewolf buddies. Yeah, Google, at times
and other search engines refused to believe that you're you're
actually searching for likings, which I think is a bit presumptuous.
(16:17):
I looked around a little bit too, and I could
not find any liking based horror films. But this is interesting.
Um the film or film adaptations of the Day of
the Triffids uh the novel by John Wyndham. A lot
of people probably know this one because there's a There's
their Killer plants in this book and in the movies
(16:38):
that are based on it. But Wyndham also wrote a
book I was reading. I have not read this, but
he has a nineteen sixty book titled Trouble with Liking,
and it's about a discovery that some sort of unusual
strain of lichen pink can be used to uh slow
down the aging process and enable people to live for centuries.
And then here's apparently a lot of speculation in the
(17:00):
novel about how this would affect society. Well, that's actually
interesting because there is a lot of research into secondary
metabolites produced by lichens as possible uh as possible candidates
for use in biotechnology and medicine. That you know, lichens
produce all kinds of interesting compounds that are of of
(17:21):
great interest too. I think, well, what's the term that
might be called? Like bioprospectors. Yeah, it's also my understanding
there have been some studies of certainly post in the
period after this book came out, that have looked at
potential anti aging um drugs that could be made from lichens. So,
I don't know, interesting topic one. Perhaps we'll have to
(17:42):
come back to in a future episode if everybody gets
liking fever from this one. Well, in fact, even a
minute ago, I was talking about that poison vulpinic acid
that is made by one of the likings that's in
the study, and even volpinic acid itself has been the
subject of a study about treating a throws sclerosis. I think, yeah, so, uh,
let's let's get back to those two likings from the study.
(18:04):
Though again, one of them is um uh is toxic
to mammals. The other is not. But here's the thing.
Previous DNA studies had ruled that the two species were
actually identical, and it was unknown why one was toxic
and the other was not. And this was seen another
liking as well, with other cases in which two types
of liking had the exact same symbiotic partners but differed
(18:28):
wildly in appearance in chemistry. So what was up? So
inter then University of Montana postdoctoral researcher Toby Spreebel, who
is now I believe with the University of Alberta, I think,
but he was the research lead on the study and
it was apparently, you know, quite a ground breaking study, uh,
(18:48):
you know, using a lot of new technology and teaming
up with it wasn't just a Spreebel here, he was
teaming up with a very talented team including u M
University of Montana microbiologist John mcmccutcheon, who had worked with
a lot of insects indiosis studies in the past. All right,
so how do we get to that trifold nature? Okay,
So what they did is they did RNA analysis and
(19:10):
found two fungal species in the test lichens, and they
found that the toxic liking contained more of it the
secondary fungus and this would be the third component of
the of the lichen turned out to actually be a yeast. Yeah,
so the original assumption was that these likings were composed
of a partnership between the photo byant and then the
(19:31):
micro bion was believed to be entirely represented by this
group called the asco my seats, which is a certain
type of fungus. But instead what they found is there
were a bunch of other fungus genes being activated that
belonged to a group known as the basidio my seats. Yeah,
and and so one the crazy thing here is, Okay,
you hear about this and you think, okay, well, they
found a really interesting pair of lichen in Montana. Well
(19:56):
it doesn't stop there, though, because they started testing lichen
from around the world, and I mean from around the world,
including like Antarcticum varieties, and they revealed that this was
not an isolated phenomenon and in the words of McCutcheon,
it was all quote hiding in plain sight for more
than a hundred years. Uh so, uh, it really did
(20:16):
shake up everything we thought we knew about liking. Even
ruined some perfectly good poems. Oh yeah, because the poem well,
I mean, I don't know if the poem is totally ruined,
but yeah, the Jane hirsh Field poem does sort of
envision the liking as a partnership between two and in fact,
it seems now that many lichens are a partnership between
(20:37):
at least two and include other elements as well, for example,
this yeast. And so when you look down at the
micro structure of a lichen, what's often going on is
that it's kind of loaf shaped, and then in the
interior of the loaf you've got a lot of fungal fibers,
and then on the exterior of the loaf you've got
this sort of crust, the structural cortex that has of
(21:00):
course the photo bion element in there, which is doing
the photosynthesis, But then it also has these yeast elements
in the crust, and so what are they doing there?
What what purpose does the yeast serve? Well, I think
in a lot of cases it's not entirely clear yet. Yeah,
based on certainly based on the writings of the time,
and I think this holds true to today, is that
(21:21):
it's still kind of an open question what this These
new third partners are necessarily doing a lot of research
is ongoing and is still yet to be done to
figure out exactly how the lin really works. In light
of this revelation in the world's just almost always more
complicated than you thought. Yeah. Yeah, you push through one
door and then you just find out that there's another
(21:43):
one that was just just a little uh further away
than you were able to glimpse. Yeah, well, should we
take a break and then come back to talk about
some like in history. Let's do it. Thank thank alright,
we're back. So, uh, you know, an important question to
ask is how long have have lins been around? Well,
(22:04):
it's a it's a it's a more difficult question to
answer than you might think because certainly the oldest for
sure fossil likened data goes back to the early Devonian
um uh period. This would have been about four hundred
million years ago, and we have this evidence from a
sedimentary deposit called the Rheiny Church, unearthed near Aberdeen, Scotland. Now,
(22:28):
to call back to a past episode, uh, the Devonian
was the age of prototax I d s and other
strange land flora. So this is one of those those
periods in uh, in Earth's history where it's it's a
it's an interesting exercise to just try to imagine yourself
standing on those strange soils well, yeah, the Devonian was
the age of fishes, but I think it was also
(22:49):
the time when we think that the the dry land
of Earth was first significantly populated by by plant life,
right right, right, So you know that, so we have
fossil evidence of lin from this time, and you know
that the question is okay, well when did liken emerge? Now?
One thing to stress about all of this is that
fossil record of lin is not all that compelling. Most
(23:11):
liken dominated habitats such as tundras, deserts, mountaintops, they don't
produce a lot of fossils. And of course we also
have to remember that the fossil record itself is inherently incomplete.
Not everything fossilizes, and and and as it turns out,
like in are are less prone to fossilization. Yeah, the
fossil record is not a clear indication of what existed.
(23:34):
It often is biased in favor of what kinds of
things get fossilized easily and what you know, there are
certain steps that you have to go through in order
to get fossilized. You have to often get buried quickly
after death in certain types of soil and chemical soil conditions,
so it's it's a finicky process. Yeah. Now, there there
are some fossils from between two point two and two
(23:56):
point seven billion years ago that have at least in
the path asked been interpreted by some as being likenised organisms.
But it's nothing that everyone agrees on. So um, so
we can't really we can't really dated back that far. Um.
But like can have certainly existed for hundreds of millions
of years. But we used to think that they were
even older, that they were perhaps even the earliest land organisms.
(24:21):
And this this has long been the conventional wisdom on lins,
and it matches up with how they are frequently observed
to behave on our own world today. Um lichn is
often documented as an early colonizer of New Land. And
again they're capable of popping up in some really rugged
conditions again you know, mountain tops, bits of of rock
poking out of the frost, that sort of thing. Um.
(24:44):
So you know, it seems to match up with what
we see. Uh. One example, I came across to give
like some some some sort of um, you know, human
level um. Uh, you know time stamps. The volcanic island
of Certaincy emerged in nineteen sixty three, and by nineteen
seventy lichens were found growing there. So I think that provides,
(25:05):
you know, a sort of a rough timeline for how
this sort of thing might occur, not in the archaic since,
but in you know, in our modern world, right, because
at least in the modern world you already have liken
symbiosis that exists. It doesn't have to evolve a new
it just has to colonize the land. But it does
colonize the land quite well. Yeah. Now, the most recent evidence,
(25:26):
interestingly enough, um suggests that that this idea of lichen
as the first colonizer of of New Earth, Uh, that
this is not quite the case. I was reading a
wonderful two thousand nineteen New York Times article by Joanna
Klein on this, uh and uh. Basically in the idea
here is that likns may have made their way onto
(25:47):
land some one d million years after ferns and other
vascular plants. And interestingly enough, this actually matches up, uh,
you know, to the extent that we can compare these
two things with the data from certain cy that Volcanic Island,
because vascular plants actually popped up there by nineteen sixty five,
that's just two years after it emerged, and mosses by
(26:09):
nineteen sixty seven. But but to be clear, we do
observe lichens filling the role of first settlers in environment.
So it's it's not like it doesn't occur, um but uh.
But anyway, based on the more recent evidence, it seems
that that lichens would have followed ferns and other vascular
plants on to the primordial Earth. Yeah, and it seems
(26:32):
especially apt to happen in certain types of extreme environments
where lichens are more well adapted than plants would be
on their own, for example Arctic tundra. Yeah. Like one
way of looking at it, and this was certainly part
of the older interpretation is that lichen would grow where
plants could not, and they would make the environment more
hospitable than for vascular plants to move in. Okay, so
(26:54):
that was the old theory, But maybe that might not
always be the case. That's right, because in two thousand
nineteen you had the study um uh from Nelson at
all published in Geobiology that pushes the evolution of lichn
to two and fifty million years ago. But they also
argue that different fun guy developed their alga hugging habits
independently and didn't inherit it from one main ancestor. But
(27:18):
it still remains a lot to be done in the
genomic study of likn. But but still it does seem
to point towards a a version of history in which
lin follows the vascular plants follows the ferns. Right now,
this is all kind of a set up to the
main question I had in the main paper that really
caught my interest here, revolving around this question, how did
(27:40):
lichn fair when the dinosaurs died sixty six million years
ago in the Kati extinction event. This is a really
interesting question because we've discussed on the show before the
role of fung gui by themselves in the aftermath of
the kat extinction. Specifically, the hypothesis us that fungi may
(28:01):
have played a role in the evolving primacy of mammals
in the food chain after the KPg extinction. Because if
you you have this period where um where much of
the sunlight is being blocked out, and so you have
this earth that's just full of dead, rotting plant and
animal matter, what's doing really well in a place full
of dead rotting animal and plant matter. It's fungus, right.
(28:24):
Fungus is the decomposer of the Earth. And so if
you've got planet fungus in the wake of this asteroid
impact or combination of asteroid impacts and volcanic eruptions, what
survives well in the presence of an aggressive fungus dominated biosphere. Well,
apparently mammals in their warm blood do a lot better
(28:45):
at protecting their bodies from fungal infection than say, cold
blooded reptiles do. Yeah. And another part of that too
is not only is the post Katie extinction world a
world full of dead things, it's also a world in
which the sky is darkened by the ash clouds, although
of what was probably a near Earth object impact, right,
(29:08):
I guess that that's what causes the dead things to
begin with. So I think that the commonly assumed cascade
is there's impact that darkens the skies, which which limits
the amount of sunlight available to the primary producers, such
as plants, so they all die off. The animals that
eat the plants can't get enough food, so they start
to die off. The animals that those animals can't get
(29:28):
enough food, so they start to die off. And it's
this trophic cascade of death creating a just you know,
an amazing buffet for the fungus of the earth. So
that this particular paper that looked into this two nineteen
study again just really driving home how much of our
like in like really exciting like in work is happening
right now. And and as ill as I'll touch on
(29:50):
two like this is a study that couldn't have taken
place just ten years ago. But this study was from
the Field Museum, um Cassette, Start University of him Young University,
and Academia Seneca, and they looked into this question that
the lead author was Jim Peng Wong, who I referenced earlier,
read a quote from him, a former postdoctoral researcher at
the Field Museum in Chicago. And so the idea here is, yeah,
(30:13):
like we've been discussing, Katie, extinction of then occurs wipes
out the non avian dinosaurs, but also plenty of other
organisms as well, a lot of early birds. Um that
they have that ash rising up into the sky blocking
out the sun. So photosynthetic organisms also suffered. Plant life
was devastated on Earth. So Huong was curious about the
lichen Uh He and his team. They suspected that lichn
(30:36):
would have suffered as well given their relationship with the Sun. Again,
that's part of lichens whole thing is that they have
the fungal element, but then they have the the alga
that that are also that are I mean, that are
capable of photosynthesis. But it comes back to the dual
nature of lichen, right because there, you know, there's the
photosynthetic aspect of of the of the life forms that
are good that would presumably suffer in this world. But
(30:58):
then there's the fungal ask becks that that might thrive. Um.
So anyway, they decided to look into this. Uh, we've
already touched on the fact that fossil records show an
increase in fungal smores. At this time, we know that
fungus was was getting to run amuck post KT extinction event.
This is planet mold. You have planet mold. But when
(31:21):
it comes to like and again like in fossils are
not common enough to really prop up a study like this,
So most of this was based on modern Like in DNA,
it involved identifying the mutation rate in species, determining common ancestors,
and they used to program to sort through these large
molecular data sets, and this is what Huong points out
is being just something that wouldn't have been possible ten
(31:43):
years ago. And all of this is also backed up
by what fossil evidence we do have and um and
this was used to see, okay, when are we when
are we observing branching occurring among the liking and at
least for some like in families. The results of all
this point to a boom in liken populations after sixty
(32:03):
six million years ago, So that's very interesting. Was that
we have genetic evidence or genomic evidence of what was
going on with with liken species diversity in general, but
we don't necessarily know all the reasons why. And there
would be some lingering questions, right like if if the
if plant life is suffering because of decreased access to
the sun and so forth, wouldn't likens also be suffering
(32:25):
because they're also not getting the you know, the sunlight
for the photosynthesis that makes their carbohydrates. But then of
course you've got this fungus component in a world where
fungus is doing well. So yeah, it makes you wonder
about the mechanisms at play. But it looks like at
least some species were doing really well and diversifying at
this time right now. Now, to be clear, some liken
(32:47):
definitely went extinct, and other lien seemed you know, they
seemed to be doing okay. You know, they weren't thriving,
but they weren't perishing. But interestingly enough, you did have
these families that thrived. Um now at Long points to
the fact that some lichens grow sophisticated three D structures
like plant leaves, and therefore it could have been these species,
(33:08):
he argues, that filled the niches of the plants that
died out. So you have widespread, uh plant devastation that
that creates an opportunity for certain savvy, composite organisms to
rise up and fill the void. That's really interesting. So
maybe after the dust clears, whatever's left might involve a
lot of lichens that suddenly have new opportunities to say,
(33:30):
access sunlight, whereas previously there would have been plant cover
blocking them or something. Yeah, yeah, I think so. But again,
like you said, this is an area of very new
stag nineteen. A lot of work still remains here, but
it is it is interesting. You have to think back
on this post extinction age and imagining, you know, at
its own pace, the lichen uh taking over alongside the mold. Yeah. Alright,
(33:54):
on that note, we're going to take a quick break,
but we'll be right back with more liking. Alright, we're back.
So to finish out here today, I wanted to talk
briefly about a paper that I will admit caught my attention,
mainly just because it's brand new. It came out this summer,
and I was looking for recent like in research, and
(34:15):
also because of a punny title. But it actually turned
out to be very weird and interesting. So the paper
I want to talk about was published in the journals
Symbiosis in July by Lucia Mugia, Polano's Allar Armando Azua
Bustos and Carlos Gonzales Silva, Martin Grube and Nina Gunde Simmerman,
(34:36):
and it is called The Beauty and the Yeast. Can
the microalgae Donaliella form a borderline lichen with Jortea vernecki
i uh so? The authors here point out that, of course,
symbiotic relationships often allow organisms to survive in environments where
they wouldn't be able to survive and proliferate at least
(34:57):
not as well if they were on their own. And
lichens are of course an example of this. You'll find
like in thriving in environments where the microbiant and the
photobiont alone would face extreme challenges. But the question is
how do these relationships evolve in the first place. What
gets these organisms working together and becoming a composite, becoming uh,
(35:19):
just a partner within a symbiosis. The author's site previous
studies showing that like and thali meaning the physical structure
of the like and go back to the Lower Devonian
as we were talking about earlier. But there's still a
lot we don't know about how these alliances between organisms
are formed in their earliest stages. They're surely interacting and
(35:39):
forming relationships before they're actually building bodies together. And one
place where we can look for clues about the early
stages of this evolutionary process is in what are known
as a borderline likens, which they define as quote species
associations showing a high degree of specialization, but without the
form a shin of well differentiated fungal layers characteristic of
(36:03):
true lins. And one of the organisms that they're studying
here really melted my brain. I love this. Uh. It
was first described in a study from two thousand ten
by Armando Azua Bustos see Gonzales, Silva, el solace, Ari Palma,
and R. Vicuna. And this was a study published in
(36:24):
the journal Extreme of Files in two thousand ten. So
the authors of the study describe a newly discovered species
of single celled alga in the genus Dunaliella. Now normally
Dunaliella is a marine algae. They're they're tolerant of hyper
saline conditions, so you salt them like a slug. They
don't really care. Uh. The scientific term for the ability
(36:47):
to live in really salty conditions is halo tolerance. By
the way, don't salt a slug, You'll just make a
nath and you'll feel bad afterwards. Oh yeah, why why
would you do that? How would you feel if a
slug salted you? Yeah? Uh So. Donaliella is a primary
food source for a lot of filter feeders of plankton
in the ocean. Uh, and a few species can actually
(37:09):
be found in freshwater sources, but this genus has always
been known as a water dwelling class of organisms. You
find them in the water, and almost always in very
salty water. Well. The study in two thousand ten discovered
an exception here. Researchers described a species of Dunaliella found
on the walls of a cave in the Atacama Desert
(37:32):
of Chile. So one of the driest places in the world.
How would the alga be surviving in a desert cave?
And at this point, I just want to read a
quote from the paper. Quote. On further inspection, we noticed
that it grows upon spider webs attached to the walls
of the entrance twilight transition zone of the cave. This
(37:55):
peculiar growth habitat suggests that this Dunaliella species uses air
moisture condensing on the spider web silk threads as a
source of water for doing photosynthesis in the driest desert
of the world. This process of adaptation recapitulates the transition
that allowed land colonization by primitive plants and shows an
(38:19):
unexpected way of expansion of the life habitability range by
a microbial species. So whoe, I mean? So many things
interesting about this. So you're you're talking about a plant,
an alga that normally lives in the water. Now living
on land. Of course it needs sunlight to survive, but
(38:41):
it lives in a cave. So how is this going
on while it's living on silk from spider web threads,
which you know, collects moisture from the fog in the air,
and then it stays in the twilight transition zone of
the cave so it can still get some sunlight in
order to do photosynthesis. This is a This is a
(39:03):
real cliffhanger of an organism. Yeah, yeah, I just I mean,
you know, most of us wouldn't think of, you know,
spider webs in the twilight realm of a cave. Uh.
And and and think to ourselves that's a that's a
great place for some uh you know, of photosyn synthetic
organism to thrive. It's yeah, it's so strange. Yeah, but
(39:25):
that's nature on the spider webs. So I love this.
And anyway, this species is now known as Dunaliella at
a commensus. And to come back to this paper in symbiosis,
the authors note something else about this species of alga.
It has been observed cuddling up to some fungus, specifically
(39:45):
another hallow tolerant organism, a fungus A kind of black
yeast called Hortatia vernecki i. So you would normally when
you look at these in these little dew drops of
water that are forming from the silk of a spy
fider web in this cave, you will find small colonies
of algae of this species at at a commensus in
(40:09):
which you will find embedded cells of this black yeast verneckii.
And as far as I can tell, there was no
previous evidence that these species were in a symbiotic relationship.
That they just appear to be huddling together, and finding
organisms in proximity to one another is not necessarily a
(40:29):
sign that they're symbiotic. You can think of examples, you know,
where you might find organisms together but not symbiotic in nature.
I think, for example, about different animal species that you
might find gathering around a savannah water source to drink.
So if you have gazelles and elephants nearby each other
drinking water, they're not necessarily in a symbiotic relationship with
(40:50):
each other. They just happen to be side by side
accessing a common resource. And so the question these authors
were looking into is, well, can we find any evidence
that these species are actually in a mutualism that they're
providing benefits to one another, and unfortunately the study encountered
problems where they were unable to get the algae to
(41:12):
grow properly in vitro. They actually tried a couple of
different algae, both at A Commensis and then another one
known as de Selena, which they note as a common
inhabitant of saltern brindes and salterns are pools of sea
water that can evaporate and leave crystal salt behind. But anyway,
so they had these these methodological problems trying to get
(41:33):
the algae to grow in the lab, and they discussed
several possible reasons for this, including the possibility that the
washing process of preparing the algae for in vitro incubation
may have removed some kind of vital environmental nutrient, or
in keeping with the findings that we were talking about
earlier from spree Bill and others, it may possibly have
(41:56):
removed some other crucial but yet unidentified microorganism partner. So
we still don't know if these organisms are involved in
what could be called a borderline like in relationship or not.
The experiment was not able to establish evidence of any
mutual benefit provided. But I do want to say I
always respect reading research that doesn't come to a conclusion
(42:18):
about its central question, but still publishes its findings, because,
for example, discussion of the methodological problems they encountered could
be useful for other researchers who were trying to study
the same thing. Yeah. Absolutely, And I guess it's easy
to lose sight of the importance of that, especially in
a sort of headline driven science consumption, Right you want
(42:39):
that especially We've already touched on some some some studies
that definitely hit that chord totally. So the question remains
about these species in particular. But I think this this
is one fascinating picture of how the symbiotic relationships that
create like and could potentially first evolve. You have two
tiny organisms clinging to one another for drops of fog
(43:02):
do collecting in a spider's web in a cave against
the water starved desert, and perhaps eventually in these harsh
conditions they could come to appreciate what they can do
for one another in an evolutionary sense, But we we
don't always know how it happens. And that that's hammered
home by another quote that was cited in ed Young's
article that was from a researcher from the University of
(43:25):
Exeter named Nick Talbot who's talking about lin and Talbot says, quote,
if the right combination meet together on a rock or twig,
then a lin will form and this will result in
a large and complex plant like organism that we see
on trees and rocks very commonly. The mechanism by which
the symbiotic association occurs is completely unknown and remains a
(43:49):
real mystery. I love it. I mean, so it happens
in nature all the time, we see it all over
the world, but it's it seems to be kind of
scattershot as to whether we can recreate a in lab
conditions or what all is needed to make the relationship work. Yeah,
it's it's it's such a fascinating topic again. Um, liking
(44:10):
are just so much more mysterious, uh and and been
beautiful and complex, and we often give them credit. Um.
I know during this trying time, those of us who
do have access to nature have you know, have probably
been taking more nature walks. I know, just based on
my own famili's activities and on various friends that I uh,
(44:32):
you know, say follow on on Instagram. I know I've
noticed a lot of people exploring their their natural world
a little bit more, getting into perhaps, uh you know,
the chronicling mushrooms in their area. Mushroom hunting can be
a great deal of fun. But liken hunting uh also
something I think it's on the table right now. Go out,
Uh look for the liking. Um, you know, observe the
(44:54):
like and heck, heck, if you want to take some
photos of liking and share them with us, uh, please
do so. We'll we'll tell you where you can email
us here in a bit. But also we have the
we have the old Facebook group, the discussion module, the
stuff to Wear your Mind discussion module. That's it seems
like a perfect place to drop some lik in photos. Yeah.
Also frankenstein up your own like and see if you
can do it? Can you incubate get some algae and
(45:16):
some fungus together and just throw them into the mix.
See what happens. Yeah, that's a good beginner level, like
an experiment for your your quarantine day. It probably won't work,
but you know, it's always worth a try. All right, Well,
there you have it. Um as always, UM, you know,
you can find our podcast wherever you get your podcasts. Uh.
And that goes without saying right wherever that happens to be.
(45:38):
If there's a way to rate us, to review us,
to give us a nice you know, smattering of stars. Uh,
you appreciate that helps the show out allegedly. Um. But yeah,
if you just have some wonderful liking experiences, some li
in sightings, or even better, if you have a liking expertise.
(45:59):
Are you are are you are you a liking hunter,
an amateur like and hunter? Are you yourself a lichnologist?
Well then we would love to hear from you. Of course.
Now we always want to say a huge thank you
to our excellent audio producer Seth Nicholas Johnson. But if
you do want to get in touch with us, you
can email us as always at contact at stuff to
Blow your Mind dot com. Stuff to Blow Your Mind
(46:29):
is production of I Heart Radio. For more podcasts for
My Heart Radio, visit the iHeart Radio app, Apple Podcasts,
or wherever you're listening to your favorite shows,
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Joe McCormick
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