Okay. So as Don said, I'm going to be talking about niche properties and niche construction by the fungus, so it was pungent. And there we go. So I think today, what I'm going to try and do is argue that one of the major gaps in our understanding of fungal community ecology is really a lack of detailed information about the details of individual species. And, you know, we're all aware and we've seen lots of examples of how high throughput sequencing has really revolutionized our understanding of fungal communities and how it's getting exponentially easier and cheaper with time. And as a result, I think we know a lot about overall changes in community composition sort of similar to this cartoon I've showed you on the left here. We do a lot of sequencing. We can look at samples from habitat one and habitat two. And we can compare the differences in composition and we often, you know, make hypotheses about what sort of environmental filters might be determining membership across these two different habitat types. And so I guess I would argue that in some ways we know a lot about sort of these overall changes in community structure much more than we do about why those changes occur at say the individual species level. And, you know, this is can pose some difficulties because we know that within the species that co occur in the same site of the same sample of the same habitat are actually often doing so even if they're responding to very different environmental cues that have brought them to that particular place. And so even though we tend to treat, you know, communities as real things somewhat akin to if you're familiar the arguments of Clements one of the earliest early very influential ecologists who kind of thought of communities as sort of a super organism where all the individual species kind of function to support the whole. In reality, I think that they're often much more like this. There was a concurrent ecologist and Henry Gleason, who argued that really communities don't exist in a real way they're just really some of all these individualistic species responses. And so if we know that species are responding very individualistically to different environmental conditions. This can cause some problems if we're trying to use these top down approaches to predict, you know what a fungal community might look like in the future.  I really like this overall kind of top down approach but I often feel like I want some more details about the fine grain biology of individual fungal species. And so, you know, my goal for this talk then is really to try and start building motivating myself and maybe other people to start thinking about how we can build a bottom up approach to fungal community ecology that's rooted in the details of individual species of fungal. And so today, what I am going to do is try and give this give a talk kind of using three vignettes that illustrate what I think can be gained from this approach. I'll be using talking about three different, what I'll call niche axes relating to dispersal and recruitment of fungi, some critical soil macronutrients nitrogen and phosphorus. And I'm going to talk a little bit about overall community composition and chemistry in the soils. And I really want to follow the studies through with a single organism, and this is the ectomycorrhizal fungus, so it was pungent. You can see this really charismatic photo of it right here. I love the Betsy's photos of all these different cultures. And hopefully, so it was strikes you as being equally charismatic. And ultimately what I want to do is try and use this information that we can glean about these different niche axes to then try and connect it with what what we know about where this organism occurs in the environment. And you know this is going to be an imperfect story. Since this is kind of a new endeavor for me trying to think about things through this lens. What I really am hoping to do is show you that by going into a deep dive on a single species. I think this actually helps us in the long run to be able to generalize out mechanism when we think about what's going on in entire fungal communities. Okay, so I want to start by talking about dispersal. The image on the left here shows Point Rays National Seashore, which is where I've been doing research for a while where Sewell's pungents occurs. This is just north of San Francisco about 45 minutes to an hour and a half depending on traffic. And really before going any further, I need to acknowledge Tom Bruns who is gratefully here for really introducing me to the system as a doctoral student and all the work that he's done here which has made much of my work possible. And I think Tom is here working on his GPS unit with that hammer.  And then this is me here in San Francisco or I'm sitting right now giving this talk. And, you know, one of the reasons that working here has been so appealing as you can look in this picture on the right, and you can see this very patchy kind of vegetation structure at the coast. In particular, here there's really one species of pine, which is Pinus miracle or Bishop pine. And this pine is really the only host for Sewell's pungents in this area, and really the most important ectomycorrhizal tree out in this coastal vegetation. And it occurs in this primarily our muscular mycorrhizal vegetation matrix which is made up of things like Bishop pine and poison out mostly as far as I can tell. And, or, sorry, of back risk polyleris which is coyote brush, not Bishop pine. And because Sewell is another ectomycorrhizal fungi are obligate by a tropes. This is really an ideal landscape for trying to understand how Sewell is pungent disperses because we can find, you know, find its host pants in this landscape and study how it moves across this fragmented landscape. So I've been studying dispersal of ectomycorrhizal fungi in a number of ways but I want to show you some results from a recent paper that was led by one of my graduate students, Gabriel Smith. And so because Sewell is pungent and other ectomycorrhizal fungi are host specific. So we know the location of potential propagable sources which is the pines as you can see kind of up at the top of this top left of this slide. And we can measure how well these fungi disperse across this landscape by kind of going out and collecting soils, bringing them back to the lab, and then assaying the colonization of bait seedlings that are growing in the greenhouse like this. And so we can look at, you know, the percentage of the root system that's occupied by these fungi and use molecular methods to characterize the diversity of these fungi. And so in this cartoon in the bottom where the y-axis shows the percentage of seedlings that are colonized by E.M. fungi, the percentage of the root system or percentage of seedlings, sorry I should say, and the x-axis shows distance away from established pine trees. If we see something like this, like really no change in colonization of these pine seedlings with distance, then this would suggest that there's really no dispersal limitation of these fungi and that wherever a pine seedling might establish this landscape it's going to be able to find its mutualistic partners. However, if you get something like this where you would see a decrease in the fraction of the seedlings that are colonized, this indicates that there is probably dispersal limitation and that an establishing pine seedling might not be able to find fungal partners in certain parts of this landscape. And what we see in reality is evidence for fairly rapid decrease in the availability of ectomycorrhizal propagules which is consistent with this idea of dispersal limitation. And now, of course, we don't just want to know if fungi colonize these seedlings but also who colonizes them. So we've used DNA sequencing to characterize fungi from the individual root tips at these different sites. And, you know, while this global model shows dispersal limitation, what we see from sequencing are really two important things. The first is that from a total ectomycorrhizal fungal community associated with Bishop Pine at this site which is probably close to 200 species. There are about 20 species of ectomycorrhizal fungal that actually colonize these seedlings. And out of that there's really only seven in this particular study that appeared with any sort of regular abundance. So there's a very small fraction of the total ectomycorrhizal fungal community it's actually very good at dispersing. And we've noticed that these fungi individually show different dispersal patterns. So, some of these, like Helvella vespertina and Tomatella subonassana disappear within a few meters of the forest edge. Whereas some of these, like the left for a terrestris and sewillus pungens, because the star of our show, they're able to colonize seedlings up to, you know, a few hundred meters to a kilometer away from the edge of the forest so they're dispersing quite well. The second thing that you might be noticing is there's actually a pattern for a number of these fungi where they appear to peak in abundance farther away from the forest edge, which seems sort of counterintuitive. And so, you know, we've been really curious about why you might see patterns like this. All right, and so I'll explore this with a little bit more of a deep dive into sewillus. So if you focus on sewillus pungens, we know from the figure I just showed you that colonization does peak at a distance. And so one possibility here is that there's some sort of mechanism where its spores tend to preferentially disperse long distances so they're preferentially deposited farther away from the forest edge than near to the forest edge. But what we know from previous studies is that this actually isn't the case. So we've gone out and use kind of spore trapping methods, along with sewillus pungens specific quantitative PCR to count the number of spores that reach different areas away from the edge of established pines and you can see that here on the y axis this is the spore deposition rate in terms of spores per square centimeter per day. And again on the x axis this is the distance away from established pines. And so we know that the spores do kind of monotonically decreases you move away from the forest edge so we can rule out that as a potential explanation. The thing we do actually know though and this comes from a study by Peter Kennedy is that sewillus pungent is really a wimpy competitor. And so what this figure shows is that this is spore inoculations of sewillus pungent and two other ectomycorrhizal fungi onto Bishop pine seedlings. On the y axis here you can see the fraction of the root biomass that was colonized. And what you can see is for sewillus pungent when it's grown by itself it colonizes a fairly large fraction of the seedling root system. And so it has one you co-inoculate it with either Rizapogon salabrosis or Rizapogon oxidant talus who also were in this last figure I showed you that they totally exclude sewillus pungent from colonizing these seedlings. And so it seems like this incredible dispersal ability that sewillus has sewillus pungent has comes at a competitive cost. So, you know despite the fact that sewillus pungent is a poor competitor, it's actually one of the most common fungi at point raise in early successional settings. And this figure shows what's known as a nestedness diagram from a study of a 10 year old tree or tree islands or tree patches. And this figure I think is one of the more interesting parts of this particular study to me. And what this figure shows is the matrix where the columns are fungi and the rows are tree patches. And so you can go here and these tree patches are kind of arranged, these rows are arranged in sort of the largest tree patches down to the smallest tree patches here.  And so, for example, Amnida Frenchetti here occurred really only on this one large tree island that I surveyed or tree patch that I surveyed. By contrast, you can see far left of this figure, this is sewillus pungent and it was really present on every single tree island that I went out and surveyed. All right. And what this figure shows is that the communities that occur on these smaller tree islands are kind of a nested subset or a subset of the communities that occur on these larger tree islands. But the reason I'm showing you this is because I think it says something about the importance of these competition colonization trade offs, because we actually see this nested pattern repeated across studies. And so this is the figure I just showed you from looking at nestedness with these tree island patches arranged according to size. And this is the same figure, this is the same kind of a figure from Gabriel's paper, but I was just talking about where these, these locations are arranged from kind of closest to the forest edge to farthest away. You can see that this nestedness pattern is repeated across this distance gradient. And, you know, we're able to do then in the same study is take a theoretical model that David Tillman had developed about spatial competition which is based on an assumed dispersal competition trade off. And using this model we're able to recreate a nested pattern parameterized with a community that would someone, something like the community we see in this size gradient study. And so what I think we see here is that, you know, so Willis is probably on the extreme end of being really good at competing and being terrible at competition, but that this pattern really generalizes across the entire fungal community. Okay, so just to wrap this part of the talk. So so this is a great disperser so as pungent is a great disperser I should say, even compared with other so Willis in this particular system. So I think by focusing on this so Willis, where we get all this really detailed information and since it's at the extreme end of this dispersal and competition spectrum, I think we can actually help to generalize this competition competition trade off to be something that is more applicable or widely applicable across the fungal community. And more broadly there's this idea of regeneration niche, which grub in 1977 defined to include all the things that are necessary for successful reproduction and dispersal, as well as the kinds of environments that they have a recruitment. And I think that this regeneration niche actually then becomes a really important way in which we act to micro as a fungal differentiate themselves, and which hopefully you can see from these nestedness diagrams that we can use to understand patterns of fungal decomposition across patterns of say habitat size or isolation, or a successional time. Okay, so, knowing about, you know this dispersal regeneration niche of this fungus, I think helps to explain some of the patterns we see in active micro as a fungal community organization, you know, across a spatial or temporal But next I want to talk about nutrients and this is often one of the things that people think about first when they begin to think about active micro as a fungal. And so up until this point, I've been using the term niche or niche of it vaguely. And when there's, well there's lots of different definitions of the term niche, probably the most widely used is Hutchinson's definition of the end dimensional niche. And I did summary quote describing this up above from from Bob hole, but essentially you can think of the niche as kind of an abstract space defined by different environmental axes. And so I put put one up here. Whoops, and I skipped ahead a little bit. And, you know, we know a lot about these for things like plants so I've got kind of a cartoon example here for say a pine. And this kind of area of, you know, if we know from physiological studies as this area of temperature and rainfall, where this pine, we know is theoretically able to survive this is known as the fundamental niche. If you go out in the environment and look for this time, you'd often find it in some subset of the subset of the environmental conditions we think it can actually tolerate and this is known as the realized niche. And the difference between these two is thought to result from competitive interactions that might exclude it from other areas that it might otherwise be able to occur in. However, this conceptualization of the niche treats body interactions as primarily negative, despite the fact that we know that species are engaged in a large number of positive interactions, such as of course, ectomycorrhizal symbiosis. So a number of people, myself included have kind of tried to incorporate this into kind of niche models and the one that I've proposed is that you could think about the portion of this kind of fundamental niche space where a treat a species is able to grow in the absence of its positive individualistic niche. And then this, you could also think of this mutualistic niche that defines the area of the environmental space, it can occupy in the presence of mutualistic interactions, which is often likely to be much larger due to the positive effects that mutualisms generally have on physiology. Okay, so how can we go about trying to visualize this mutualistic niche. Ectomycorrhizal fungi, as I said, probably the most important niche dimensions are the host plants they can colonize, but also the two key macronutrients that we think are the primary currencies they provide for their hosts, so nitrogen and phosphorus. So to try and test some of these ideas about this mutualistic niche, a postdoc in my lab, Michael Van Nuland and I designed an experiment to grow pine seedlings in a factorial continuous gradient of nitrogen and phosphorus concentrations. And you can see an example of, you know, the experimental layout for one, one replicate of our study here. And so we used seven different factorial combinations of increasing nitrogen and phosphorus concentrations. So seven by seven, a single replicate of this experiment had 49 seedlings in it. So we used an artificial soil so that we could totally control nutrient inputs, which we did by modifying this pine specific fertilizer called ingust ad solution. We kept the recipe sort of normal, other than changing the nitrogen and phosphorus concentrations from point one to about 6.4 times the normal concentrations use in ingust ad. So, to try and connect this back to the mutualistic niche concept we grew the seedlings either alone. We used spores of soulless pungents, inoculated with spores of fluff or terrestris one of these other common fungi point rays, or with spores of both of these fungi. And we waited for about nine months and then harvested the seedlings, weighed their biomass and measured the percentage of roots that were colonized by ectomycorrhizal fungi. So here's a diagram of the kind of data that I want to present. At the bottom on the X and the Y, you can see this seven by seven combination of the end and the P treatments. And so on the top left, you can see it's an increases. And P is going to stay the same if you kind of stay hug the axis there. So you get your highest nitrogen to phosphorus ratios over there. And this is probably kind of P increases across this axis. And so over here we're going to get our lowest end to P ratio so highest phosphorus lowest end. And then in the middle kind of you track the one to one this is going to be the area with the highest total nitrogen and phosphorus. And then if you look up in the z plane. This is where we're going to map performance either the fungi or the plants. And so what we're going to do is kind of use the data we get to map this response surface that charts fungal or plant fungal growth or plant growth across these gradients. And then you can calculate the total volume occupied under that surface using something known as a convex hole. And while biomass isn't a perfect representation of fitness or population dynamics, we can use this as our best possible representation of the niche space that's occupied by each species. And this is the niche space that we mapped out using this approach for a soulless pundit. And you can see there's a few things that jump out right away. So first, if you look kind of over here, you'll see that colonization is lowest, either when nutrients are kind of at their absolute low, or over here where there's lots of nitrogen and not very much phosphorus so kind of high end to P ratios. And then by contrast, you can see that colonization is highest over here, where phosphorus levels are very high, but nitrogen levels are relatively low so and becomes the most limiting nutrient and this is where so well seems to do best. And so it's actually the ratio of these two nutrients, as well as the absolute magnitude of their concentrations but the ratios are really important that tend to predict niche occupancy for this fungus. So if we go to Cilephro, this is where things get even more interesting, you can kind of see that there's the exact opposite pattern. And so you can see that its peak is where N is abundant so these are the areas where our highest nitrogen levels and phosphorus is kind of over here at its lowest level so it kind of peaks over here when there's lots of nitrogen and not much phosphorus in the system. And by contrast, when there's a lot of phosphorus and not much and this is when it has its lowest colonization levels. And when you put both fungi together, what you actually get is kind of maximal colonization across this surface, which suggests that having multiple partners allows the plant, some environmental flexibility. So unfortunately, we didn't separate out fluffer, trestress and Sewell's pungent colonization because this is already a lot of work so we don't know who was colonizing where but that would be an interesting next thing to try and do. Okay, so there you can see those, those are the two areas where in general when there was a single species either Sewell's maybe failed to colonize over here and fluffer failed to colonize over here but by having both of them together. The plant is able to maintain maximal colonization levels. So I want to turn out of the plant side and think about how this resource specialization from the fungi affects post plant growth. And this figure is a little bit different because now we're comparing plant biomass between the control of these non micro as a plants with the colonized plants. And so when you look at this figure, the warm colors are going to show where the fungus improves plant growth or expands the plant niche. And these cool colors show where it contracts the plant nature reduces the plant niche reduces plant growth relative to the control. And so for Sewell is on the left here, you can see that this is a somewhat complicated response surface, but that in general plant biomass is most approved here kind of at the top right where P is abundant but nitrogen is limiting. All right, and this makes a lot of sense is reflects what we saw with Sewell colonization data to large in the large part. All right, and for telephora again, we see the opposite pattern, where telephora seems to maximize plant growth, when n is plentiful and P is limiting. All right, so this together this kind of suggests that this niche specialization of the fun guy is directly reflected in this mutualistic niche space that is able to be occupied by their plant host. All right, so the next part, maybe some of you were thinking this that this is what I expected is that because these two funds I have really complimentary nutrient niches. What it seems to suggest is that the host could then maximize the environmental niche space if can occupy by having a diversity of partners and switching associations depending on the environmental context right. Okay, so this is where if you thought that you were wrong, and I was incorrect. Well, so we found something quite different so this is the figure that looks at plants growing with both the left for a trustress and Sewell's pundits. And what we find actually is that having in this particular experiment having two partners tends to depress the benefits that you get from being my carousel. So over here in the top left corner. Now what we see is that with the left for a trust just we're actually able to maintain pretty comparable benefits when phosphorus is limiting. And there's lots of nitrogen it still seems to improve plant growth. But when you look over here at the place where the left for our solace tends to be the beneficial for the plant host that actually these benefits tend to get suppressed here in the presence of the left for. And so this is probably because Sewell's pundit is actually kind of a weak competitor. And so that in the presence of another fungus, it's not really able to confer the benefits that might otherwise to the host. And interestingly as well you can see that it is also this kind of exaggeration of this of this kind of poor performance space here in the middle. So this is where kind of neither and or peer limiting cities are kind of in kind of equal stoichiometry compared to what the plant probably needs, which is actually quite interesting that it's more about which nutrient is is there isn't limiting that determines, you know when a fungus can actually be beneficial. All right, so it seems like these fungal interactions can actually have a negative effect on the host and complicate our understanding of functional complementarity. So first, while this is a really labor intensive thing to do. It's possible to use these kinds of approaches to map out. We think of this niche space for symbiotic organisms and look for evidence of this neutralistic niche, which we see, I think in this particular study. So doing this actually reveals some really informative things about the nature of the nutrient niche for a soulless and other fungi. And so as I said, first we see the absolute nutrient concentrations are of course important but really that also these relative concentrations and stoichiometry of nutrients are really important as well. What it means is that these two niche axes are interacting with each other, and you can't understand a niche axis alone so we just measured, you know, soulless growth along an axis of nitrogen, and tried to predict how it would, it would do a different. When you had, if you have different sort of levels of phosphorus you couldn't do it. So you need to measure both of these axes at the same time. And finally, we saw that even though there is interesting niche differentiation between these two fungi in a way that suggests functional complementarity in a very appealing way. In contrast with this kind of avatar view of the world where everything is functioning for the good of the whole. We see that these interactions between an individual fungi are often antagonistic and need to be accounted for when we think about things like functional complementarity. Okay, so hopefully it's quite obvious how, you know, defining the nutrient space or the recruitment niche of soulless pundits can determine, you know, help us understand what kinds of habitats it might occur in, or where it might be beneficial. So why is this important more broadly. And the thing I'm going to argue is that this regeneration niche and this nutrient niche for as well as pundits actually dramatically influence the rest of the environmental microbial community through this process of niche construction. So niche construction is the process by which an organism alters its own or another species local environment, and thus changes the selective pressures that they are another organism experience. So how does this apply to soulless pundits. Well we know that based on this regeneration niche that soulless is one of the most common partners of pine seedlings establishing and coastal scrub vegetation. So we've shown in other experiments that the presence of soulless pundits is really critical for pine seedlings to be able to out compete seedlings of this other really dominant are buscular mycorrhizal shrub back risk pillarus that coyote bush. And so, you know, soulless pundits dispersal ability can really help change the trajectory of the plant community by helping its, you know, helping its host plants establish and out compete. Other plants and kind of transform the plant community. And we know that the type of plant species and what root symbiosis they have can lead to very different trajectories in the development of the overall soil kind of chemistry of plant rays. And really changing the soil nitrogen carbon concentrations of the nation. We have this is from a study by a postdoc from my lab, Marty do Hamel, we looked at, you know, 20 years after fire, what a change in vegetation from back risks that say either Bishop pine, see an oath this or staying the same as back risk would do to the soil chemistry, and it has really extreme effects so you can often lead to think we calculated this over the extent of a fire that had been there. There are changes in things like thousands of tons of carbon and hundreds of tons of nitrogen, depending on which way these plant communities are shifting. And we also know that the establishment of these different plant species and the changes in the soil environment, change the selective environment for the rest of the microbial community. And over the 20 years we've chat track these changes in plant communities and their effects on the overall soil microbial communities, we see really different trajectories depending on which plant species established and how the environments have changed for the entire community of fungi bacteria and archaea, not just direct to my carousel fungi. And this of course changes the feedback feedback to change the fitness landscape for as well as pungent itself. Okay, so hopefully, I've convinced you that this bottom up approach is an interesting and useful way to think about fungal communities. With a deep dive into the ecology of a single species can actually help us to make better broad generalizations about what's driving the community assembly for the entire fungal community. And with that, I will say thank you, and I'd be happy to answer questions when it's time.


That was the whole stand doing it as the Rock is sliding through. Now it's just for Heliti onside! And he scores! 11-0 Heliti with 10 minutes to go and gets the run and play. The watchers lead! Well, it's a brilliant goal in its inception and a fantastic finish from a lady. It's a clinical finish. Collins picks up the ball. A little touch there for Bridge was perfect. He's onside across the keeper. He'll score every time. Brilliant finish. Kept his composure. Run with no chance.