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Soil ecologist Dr. Ylva Lekberg explains the connection between microscopic fungi and invasive plants, and Jessi from Animal Wonders introduces us to Sydney the woylie!

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Hank: Hello, and welcome to SciShow Talk Show, the day on SciShow where we talk to interesting people about interesting stuff, stuff that they're doing in the world.  Today, we're talking to Ylva Lekberg.  Hello, you are all up in the dirt.  

Ylva: Yeah, I work with dirt.

H: So you spend a lot of time--do you like, spend a lot of time in the dirt?

Y: I spend less and less time in the dirt, you know, as a grad student, you spend a lot of time taking soil samples, but now I sometimes try to get other people to do it for me.

H: And what is your--what are you titles, 'cause you have multiple jobs?

Y: So I'm a soil ecologist with MPG Ranch, which is a local organization here in town and I'm an adjust at University of Montana.

H: So you study what makes plants go, I assume?  'Cause soil on its own is interesting, but mostly it's all about like, okay, so these things are important.  We get our, you know, our furniture and our food from plants.

Y: Yeah, that's true.  As a soil ecologist, I like to flip that around, though, you know, 'cause it's--

H: Okay, we don't get anything from plants.  We get it all from the dirt.

Y: It's very--well, yes, I would argue that if the dirt isn't right, like, plants won't grow, so you need to understand the dirt, and more, I mean, more pointedly, the organisms in it and all the processes.

H: Right, 'cause it's not like, we think of--I think of dirt, or I thought of dirt, before I took a terrestrial ecosystem ecology class in grad school, I thought of dirt as an inorganic thing, as just a bunch of--it's mud.  It's particles of dead things.

Y: Yup.

H: And, you know, sand and rocks, and maybe there's some like, macroscopic things in there, and like, worms are pooping out whatever worm poop is, which is good and you think of worm poop as good, but there is, in fact, a lot of life in there, just like we have a lot of life in our bodies helping us  make it work.

 Y: Exactly, I mean, you can imagine, if you didn't have the saprotrophs that decompose-- (02:00) to (04:00) H: What was that?

Y: Saprotrophs, the ones that live on dead organic matter.

H: Okay.

Y: We would just have dead organic matter accumulating and we would be drowning in it, but now we have bacteria and fungi that decompose that, releases nutrients that the plant can take up again.

H: 'Cause otherwise, I guess you would just sort of end up with a big pile of dead stuff.

Y: Yeah, yeah, yeah.  Nothing would grow.

H: Saprotrophs.  

Y: Yeah, saprotrophs.  

H: And then, do you study--this is mostly what you study?

Y: No, no, actually, saprotrophs are more or less unknown to me.  I study mycorrhizae fungi.

H: Okay.

Y: And they're called mycorrhizae because they're fungus root.  Mycorrhizae.

H: So they're fungus that live around and hang out with the plant roots?

Y: And inside the plant roots.

H: Oh, so they're in there.

Y: Yep.  They get all of their carbon from the plant.  

H: So like, we are hearing more and more about like, the human biome, where we've got all this like, huge ecosystem living inside and on us, and that is also true of all plants?

Y: Yeah, I would say, like, there is an amazing diversity around plant roots.  We have the rhizosphere, that is the area around the root that is affected by carbon that is exuded from the plant and it's a really, a rich environment.

H: So the plant, there's stuff coming, like, I think of roots as going in.

Y: Yeah, but there's a lot of carbon leaking out.

H: Well, why does it come out?

Y: So part of it is you just have dead cells and they decompose and bacteria and fungi use that, but they also, there's also active acidation of carbon to stimulate microbial activity on the rhizosphere.

H: So they're doing it on purpose?

Y: They're doing it on purpose and up to 30% of the carbon that is fixed in photosynthesis can go to these mycorrhizal fungi.

H: So--

Y: So it's a costly symbiosis.  

H: Wow.  So in addition to like, that carbon would otherwise be going to make leaves and flowers and fruits and--

 Y: Yep, yep, or grow others roots, yeah.  All of the carbon that is fixed in photosynthesis that plants could use for other things can be allocated to these mycorrhizal fungi. (04:00) to (06:00) H: Wow.

Y: And instead, you know, the plants, because these mycorrhizal fungi help the plant take up nutrients, so they replace the root function to some extent, so therefore, plants often grew less--grow less roots.

H: Let's talk a little bit about fungi.  First question, is it okay if I say fungi?  

Y: I'm okay with that, yeah, yeah.  Fungus, singular.  Fungi, plural, yeah.

H: Okay.  I won't, I won't, but I just, for people who are out there, so that you know you haven't been doing it wrong your whole life.

Y: Yeah.

H: "Cause you ruin the joke, the joke about the fungus that everybody invites to the party, 'cause he's a fun guy or whatever it is.  

Y: Yeah, I've heard that before.

H: I'm sure.  I'm super unsurprised.  Second, we think of fungus, mostly I'm like, mushroom.

Y: Yeah.

H: It's the thing which is like, I can point to it and I can eat it and but, just like there's a whole world of like, animals, there's a whole world of fungi.

Y: Yeah, exactly.  A lot of them are microscopic.  The fungi I look at, you can't just pull up a root and see if it's colonized by these fungi.  We have to use microscopy and staining to see that they're there.  

H: So what's your active research right now?

 Y: I was hired to look at plant invasion and look and see how these mycorrhizal relationships are--differ between native and invasive plants, so I've worked a lot with (?~5:20).  So the first thing I did when I came to Missoula was to basically go out and see our, just, you know, when they invade, do they change fungal abundance?  Are the fungal communities different between native and invasive plants?  And we had this idea before we did this that invasive plants somehow rely less on these fungi and that might be why they're so successful, you know, because they can go to a new place and they don't really care if these fungi are there or not, but what we found was that it differed a lot among invaders.  So, (?~5:57) actually have a really close relationship with these fungi and there's research that have shown that (?~6:05) becomes more competitive towards native plants when these fungi are there and leafy (?~6:11) grows bigger in greenhouse innoculations when you add the fungi compared to where it's not there. (06:00) to (08:00) So these fungi may actually help them become better invaders.  

H: Was that fungi there in their native area?

Y: That's another thing we've looked at.  A lot of the invaders that we have here are actually native in Turkey, so we can go to where they come from and we can say, okay, who has come here and who is successful when they come here and the same thing with Argentina and there's an overlap between Argentina and Turkey as well, so we can compare different areas and I did the soil ecology aspects of that, so we've been looking at fungi and bacteria and do they differ between these places, and they're quite different.

H: Okay, so they don't like, they didn't like, come over and bring their fungus with them?

Y: They didn't bring their own fungi, no.  In New Zealand, we never had pine trees naturally in the southern hemisphere, and they started these different plantations to get wood and they didn't get them to grow very well.

H: Interesting.

Y: So they introduced the mycorrhizal fungi from the native habitat and some of them started spreading and that also allowed these pines to spread as well, so now, pine is a serious invader in New Zealand, which could partly be because they brought their own fungi with them.

H: Right.  Like, they weren't successful until the fungus came.  

Y: Yeah, yeah.

H: Interesting.  I'm definitely seeing, like, we're understanding things better.  Are there practical uses to--is there a way to control invasive plants or increase crop yields or--?

 Y: Yeah, in the 80s and 90s, there were a lot of research going on in terms of mycorrhizal fungi and agriculture.  It didn't really go anywhere at that point because at that point, we had a lot of fertilizer and we watered, so we really substitute a lot of these function that the fungi provide by adding these other inputs. (08:00) to (10:00) I think it could become increasingly important in organic agriculture, for example, where we wanna try to utilize and get the benefits of all these natural interactions.  I think there is a renaissance there to try to understand that better.  In my work with invasions, the first step is obviously to characterize how does it change.  

H: Understand it, yeah.

Y: And then once we know how it changed, to try to understand how we can change it back.  For example, one thing that we found with knapweed and spurge invasions was that they actually harbor more of these fungi and more diverse fungi than remnant native communities.  A lot of people think that you need to reintroduce these fungi after invasion.

H: Right.

Y: 'Cause there's this idea that invasive plants reduce the abundance, but we've shown that it totally depends on what invader is there, so in some cases, you actually have a higher abundance and more diverse fungal community after some invaders.

H: Sometimes I think, like, what, like, what is it that makes leafy spurge so good at living and also knapweed, but the thing that they're good at is not getting eaten by animals.

Y: Yeah, so that's the whole enemy release hypothesis and that's probably the most prominent hypothesis in invasion biology.

H: Right.

Y: The whole idea that you escape your enemies and you come and you can start fresh and everything that you would allocate to defense, you can allocate to growth.  Leafy spurge, I'm fascinated by that plant, though, because you--

H: It is--it's a powerful enemy.

Y: It's powerful.  It has deep roots, it does really well under drought, and when you analyze leaf tissue of leafy spurge, it's--it has so much nitrogen in it.  It's on par with (?~9:36) which is a nitrogen fixer.

H: Wow, yeah.

Y: And we have no idea where that nitrogen comes from, so that's part of what we're looking at on the ranch.  Like, I've actually planted leafy spurge and knapweed into experimental plots.  That means that you can follow how do they change this soil communities and ecosystem processes and how quickly do they do it, and even there, we see higher nitrogen availabilities and spurge communities, and so it's not just that they find areas that has higher, they modify the soil condition to make it more fertile.   

H: Good on them.

Y: It's fascinating.

H: If only an elk could eat it, or a cow, I guess is the main concern.

Y: Yeah, yeah, yeah.  I mean, the whole question is like, it will eventually find a balance, probably, like--

H: Yeah.

Y: Enemies will catch up, and in the meanwhile, we're trying our best to get rid--

H: Just gotta genetically engineer a cow with a little bit of goat DNA so that it can handle spurge.

Y: But would you wanna drink the milk though, is the question.

H: Then we genetically engineer ourselves so that we can have latex milk, it's all, it's great.  

Y: And where does it stop?

H: Science solves every problem.  Well, I'm fascinated and I went and learned a bunch of stuff.  I hope that you did, too.  Do you want to meet an animal?  I've heard that it eats fungi.  

Y: I would love to.  

H: Alright.

Y: Yeah.

Jessi: This is Sydney, and she's a brush-tailed bettong, also known as a woylie.  These guys come from Australia and they're in the kangaroo family, so they're a macropod, but she's teeny tiny.  She's one of the smallest in the kangaroo family and she may be a little nervous.  There's a lot of bright lights here, and she's nocturnal, so she's, she's doing really good right now, but she may shiver just a little bit to get some of that nervous energy out.  Some of the cool things that they do is they are great for fungus dispersal, spore dispersal, so they eats of like, bulbs and tubers and seeds and stuff like that, but their main diet is mushrooms like truffles.  

Y: Oh, wow, yeah, yeah.

J: They grow under the ground and they use, they have an excellent sense of smell, and they'll use their nose, they'll sniff out a fungus under the ground and they'll--they have these tiny little like, T-Rex arms, really well developed nails, and they'll dig up that little mushroom and eat it, and then the mushroom, the fungus has to be digested by a special bacteria in their stomach so they have a really efficient digestive system, I would say, and so it can, to get all the nutrients out, but it doesn't effect the spores. 

Y: But the spores survive, yeah.

J: Yeah, so then, they'll go around and they'll just, you know, poop spores out all over the place, but they also do, they'll cache, too.  So they'll grab a bunch of seeds and other stuff and they'll make holes.  They'll put it in their little cheek pouches and they'll go and they'll spit it out and so they're doing seed dispersal and fungal spore (?~12:21)

Y: Yeah, so they innoculate the seeds at the same time.

J: They do, yeah, so these guys are really beneficial to their environment.  Unfortunately, they're not around very much anymore.  

H: There are not a lot of--these--was this little guy born at Animal Wonders?

J: Yes, yes, so we rescued a male and later, we got an adult female and they bred and we had a little conservation project going on at Animal Wonders.  She was their 5th joey that they had and then we sent that pair on to a larger facility so they could continue that process.

H: They're good at it.

J: They are.  They have a baby about every 100 days, so gestation is 21 days and then they give birth.

Y: Oh wow.

J: They're marsupials, though, so little teeny tiny little guy crawls up into her pouch, and she does have a pouch.

H: That's almost like you shouldn't count that as gestation.

J: I know, right?  I know.  21 days.

H: Well, like possums like, two weeks.  

J: Oh gosh, yeah.

H: But it's not, it's still like--

J: It still is there, but it's so tiny.  

H: A pencil eraser.

J: It's like, it's like a ti--a small, it's like a jellybean.  Smaller than a jellybean.

H: Yeah.

J: And um, but then they, they stay in the pouch for about three and a half months and then they come out and they start hopping around and then the next one starts developing and--

H: My goodness.

J: They get booted out when the other one--

H: You would think that they would be able to do okay in the wild with that breeding strategy.

J: You know--

Y: What is it that threatens them, like what--

J: So initially, the interaction of the red fox.  I mean, they're tasty little morsels and they weren't used to that type of predator.  They knocked them down really, really hard and then they did fox population control and they made a huge--they came off the threatened list, so in 1996, they were like a huge, you know, celebration.   The first Australian mammal that was taken off the endangered species list.  Then, in 2001, they hit their peak, and since then, it's been just this--they've lost 90% of their population.  It's just--

Y: So is that disease or something else then, or what is it, if it's not fox?

J: They're still studying it, so foxes are still an issue.  They think a couple things happened.  Habitat loss.  Um, they changed fire, you know, where they would do burns.  There's more farmland now, but right now, they think a huge culprit is feral cats.  So feral cats are not just preying on them, but they also have several parasites that they spread to these guys and since these guys dig in the dirt so much, they're getting cat poop on their hands and their mouth and their stomachs and so toxoplasma is one that they're really looking into.  It's a parasite that goes into their brain and affects them, so they're not scared of cats, and then they become even easier prey, but new research is saying there might be a secondary parasite.  The Doyley Conservation and Research Project is ongoing.  They're studying these guys trying to figure out how we can keep 'em on our planet.  Maybe we can get them re-established.  They breed really well.  Most recent research, there's about 5,600 individuals left.  They used to cover 60% of Australia, and now they're in these three tiny litte preserves, but they are in Europe and America now in breeding, conservation breeding situations.

H: It's nice to have an animal that can at least breed well in captivity.

J: Yes.

H: So maybe we can get to the point where, once we get cats and foxes under control.

J: We can get them--you see how she stands up?

H: Yeah.  You're doing so good.

J: You're a good girl.  She's our fifth joey born at Animal Wonders, so she's been with me her whole life, and she's been doing programs--sorry--she's been doing educational programs.  We kept her because we already sent off a bunch of joeys to other places.  Her DNA is pretty well represented in the genetic pool, but you know, we still want to do education with her, so maybe in the future, she may breed in the future, we'll see.

H: Is that just a counterbalance tail?  It's big and thick, does she grab stuff with that? 

J: So, yeah! Yeah! This tail is really cool. So, kangaroos mostly use their tail to lean on, and go up on and attack. So, two kangaroos would go up to each other and they would scratch each other and then kick. These guys use their tail to balance like that too, and they hop just like a kangaroo. But the way they fight and their tail is a lot different than a kangaroo. So this tail is pretty cool because it is semi-prehensile; they cant, like, climb a tree and then hang with it. But it curls in a circle, see, there are pretty well defined creases right there. She will gather branches and leaves and sticks into a pile, and then she'll wrap her tail around it, and then she'll hop back to her little nest.
It is super cute, they'll hop around with a little bundle around their bum.

H: That's good! It's a good little backpack.

J: It's good.
Um, but then the way they fight, instead of going right up to eachother; I mean, they do a little scratching with their (claws). But they get really dramatic about it, they hiss, and their tail will start swishing back and forth and they'll both flop on their sides and just start kicking ferociously with their back legs, and grunting and hissing and (rarara *cute growling noises)
It's pretty dramatic.
Would you like to touch her? She's doing really good. Give her a pat on the back (as an invitation to Hank).

H: Oh! Thats nice.

J: Good girl!

H: it is going in every direction here

J: Yeah, it's like, *Poofy*
She, likes, when we are back at animal wonders and she is really calm she likes belly scratches so I was just gonna.
So, she does like this, she likes behind her ear, I think those are mostly just like she tolerates those. But, lets see if she will let me get a little belly scratch.

Y: It's interesting how we think of animals as being so different from us.

J: No, they have preferences too.

Y: Exactly!

J: Here's her pouch, do you want to see?

*purring noises*

J: if I can get it, feeling her pouch here, it's like a belly button, that just keeps going

*noises of awe*

J: got it

H: Is it fuzzy in there?

J: Nope

H: Oh, gosh

J: It is, like, sweaty skin  *laughter*

J: Oh! I wanted to say one more thing! So there is new reasurch with these guys, everyone is really concerned that they are going to go extinct, they are not doing great recovering. But they recently just discovered a new parasite that coexists on them, and they really perfer Brush tail patongs, it's a tick, you know, everyones favorite animal. It is Super species specific, and they think that if these guys go extinct that that tick is also going to go extinct.

H: Oh No! How terrible! (sarcastically)

J: But! You know, parasites do weird and intresting things so like the toxoplasma ---

H: You are never going to convince me that ticks are good.

J: I know, I know, but! But what if the tick is helping them some how (H: maybe) and the translocation process. What if the ticks are in their nests and if they don't go with them when they are relocated and somehow they are benniffical to something or other, because they don't know what is going on, so. It is multifacceted reasurch I don't like ticks but I...

H: It would be cool if there was a tick that gave you some kind of power.

Y: But then you take it to the next step of biocontrol and we have done that a lot with invasive plants that is so hard, it might work in the labritory then you bring it out in the feild and you have all these interactions you could never predict.

H: You mean, like bringing something into ---

Y: Yeah, you bring the natural enemys from Europe and release them here

H: And then they don't have any enemys

J: And then they take over and you try something else

Y: In some cases I think it actually has control to some extent, there are about 30 different biocontrols that have been introduced by mapweed I think it is also doing something with leafy(?) Birch because I have been trying to do something with these Birch seedlings because these birds come in and they totally disseminate them, the only way I can get this birch to grow is to put insectiside. Anyway, that is a side busness

H and Y: Wow!

H: Do you know that they are introduced beetles?

Y: Yeah, because they don't occur naturally.

A: I hope these guys make a recovery and that they keep doing reasurch on them.  We will keep doing education, getting people to like these guys becuase they are super cute! And they do some amazing things, if we can just figure out what is going on with them and get them back out there.

Y: Thats the thing though, we find out afterwards. There is so many facinating interactions in the natural world and we will never even know about them.

A: I know! If these guys would have gone extinct we would have never known about the tick.


Y: Maybe that is knowledge I can be without.

A: Can you say hi? (to Sydney)

H: It was very nice to meet you Sydney.

A: She's like, what are you doing with that finger? Just pet me.

H: Ok.
You like little bitty ear scratches?

J: Shes like ok, that's enough.


H: Thank you Jesse!
If you want to see what Jesse is doing and all of her very cool animals she has a YouTube channel at Animal Wonders Montana. You can search for that. Do you have a paper for us to share.

A: A Paper?

H: Yeah we can put it in the coments.

A: Sure!

H: Something we can read about.
Well, thank you all for joining us, thank you for watching, for hanging out, there is always more intresting science to be found in the world and we here, try to bring it to you at
*outro music*