 My pleasure to welcome all of you to this last part of Bio1B. My name is Bruce Baldwin and I'll be the instructor for the last part of the course. And my office hours are going to be held right after lecture on Monday Wednesday and Friday, over in the Bio1B area where John Hosenbeck held his, so just outside of Mike Moser's office over in 2063 on the north wing of the building here on this floor. And if you can't make those office hours, just reach me at that e-mail address, bevaldman at Berkeley.edu, and I'll get back to you as soon as I can. The way we're going to operate this part of the semester, I think it's pretty much the way that John and Alan did, which is that I'll give my lectures and after I've given the lecture, I'll post a PDF on B-space of the lecture slides. And if you go to the 1B site, you can find my syllabus already posted with the readings there, and the rough topics for the rest of the semester indicated. But the exam's going to be on the lecture material, and of course the lectures are being video cast here as well. But I really highly recommend you to read the readings to get a little more context and fill in a lot more detail about the topics I'm going to go over because the book is actually excellent. I was really surprised to see how good it is for the botany part of the course. So I highly recommend you do read those readings. So just curious here, how many of you have ever had exposure to plant and fungal diversity, say in high school biology? Can you raise your hands if you have? Actually more than I guessed. This is often an overlooked topic, but it's actually central to biology. Many students feel like this is just something they have to get through, but plants are responsible for our oxygenated atmosphere, for our ozone layer that protects us from UV radiation, for essentially all of our food and actually the bulk of our medicines, pharmaceuticals which are either based directly on plant products or botanical products or in many cases were inspired by those products. And if you're interested in learning more about that, there's an excellent course in medical ethnobotany, IB 117 that Tom Carlson teaches here in fall and summer sessions that has been really valuable to a lot of aspiring physicians, medical types. And it might be interesting to know for you that back in the 1700s, 1800s, that any self-respecting physician would also be at least at some level a botanist, and the people that really led to the creation of botany as a field were physicians. MDs were some of the first really major contributors. So the relevance of this to biology and medicine is really important and I hope that becomes more clear as we go along. So are there any questions about the overall sort of way we're going to proceed here? Yeah. Yeah, the lecture material only. But the reading supplement the lecture to give you a little more context, to flesh it out a bit better for you. So I highly recommend that. So today what I'm going to do is just basically give an introduction to what are plants. That may seem like an absolutely ridiculously simple question, but it's not really. And then we're going to start right in to looking at some of the coolest of the botanical organisms in the broad sense, the fungi, some of their important characteristics and the major groups of which there's been a lot of advances in recent years. So what we call plants and what really kind of dictates the overall subject matter for this part of the course really goes all the way back to Aristotle, to the ancient Greeks. Aristotle concerned himself with what animals were and basically defined animals as groups. I'm paraphrasing here, but more or less organisms with sensory and perceptive capabilities that could move freely about, could experience pain and pleasure, fear, could respond quickly to stimuli, that sort of thing. Those were the animals, the plants are everything else. Okay, the residuum, the things that also share with the animals this ability to nourish themselves, take care of themselves, reproduce, but don't really have anything going on up here. You know, they're pretty much devoid of sensory and perceptive capabilities. And this was more or less enshrined in the taxonomy by Linnaeus who's been considered the father of taxonomy. He was actually a physician, as I was just mentioning, also a botanist and a zoologist. And he came up with three major kingdoms of existence, formal taxa. One of them was the mineral kingdom, which is the non-living kingdom and we'll leave that to the geologists and such, but also the animals and the plants. So that view came about, Linnaeus, that's about the mid-1700s. So we have this view of animals as things that can move about, have sensory and perceptive capability. The name animal, the etymology literally means soul. So things with a soul, whereas plants don't have a soul. There's zoology science focused on animals. Plants are basically everything else, as I just mentioned. And botany is the science focused on everything but animals. So botanies really had a huge scope of focus organismally throughout history. And it wasn't until about the late 1960s, a little over 40 years ago when microscopy became a lot more advanced. We have electron microscopy coming into the scene and people really get into the details of unicellular organisms that this Five Kingdom view of life was proposed. And in here we have, again, the plants and the animals, but pulled out of the plants are now the fungi. These other groups, this major group of things that don't move freely about but are non-photosynthetic, that are not autotrophs, they can't produce their own food. And these are the main multicellular groups here. And then among the unicellular groups, there were two major groups. One, the protista basically was all of these unicellular life forms that were becoming much better understood. There were eukaryotes. And then the manera basically takes in all of the prokaryotes, which are unicellular organisms. We're talking here about what's been loosely called bacteria. And some people would include viruses there, but we can debate about whether those should really be considered forms of life. So just to make sure everybody's on the same page here, the prokaryotes are the eukaryotes. This literally means, you means true. So these are the true nuclei bearers. A carion refers to a kernel or the nucleus. So these are organisms that possess a membrane-bound nucleus, where the nuclear chromosomes are located, and membrane-bound organelles that are important for various metabolic processes. For example, our mitochondria are organelles that where respiration reactions are located. And those organisms that are photosynthetic then have plastids, chloroplasts, for example, where the reactions of photosynthesis are localized. So those are eukaryotes. And as I mentioned, they include the protists, the animals, plants, and the fungi, four of the five kingdoms. And then the prokaryotes before the nucleus, literally, these are things presumably more primitive that lack a nucleus and membrane-bound organelles and just this one kingdom, the manera. This is the system that was in place when I was a grad student, when I first was involved in teaching botany as a GSI. And this pretty much held in place until the 1990s. And what happened to change this view was that in late 1980s that Cary Mullis basically figured out the idea of PCR while he was tripping on LSD. And that became the method by which molecular biology underwent this huge revolution. And we were able to sequence the DNA relatively easily for a wide array of different organisms. And we didn't even have to isolate those organisms. You can imagine a lot of these unicellular organisms, very difficult to actually isolate. If you can't culture them, it's going to be very difficult to discover them. And so there was a huge amount of undiscovered diversity among the unicellular organisms that was discovered by PCR, just environmental PCR, where we actually are amplifying DNA out of raw soil samples or seawater. And all of a sudden, all this life became evident that nobody had even seen yet. And what that revealed was that there was a major oversimplification of this view of the prokaryotes. Prokaryotes actually broke into two major domains of life, what we could call the true bacteria here. And then this other group called the archaea. And the name refers to archaic, this presumably ancient group that has really bizarre biology that seems to predate the oxygenated atmosphere in many cases. So the phylogenetic analyses then showed that the eukaryotes, which I'll get back to in a moment, were also much more interesting and diverse than thought. But they represent basically a group on par with diversity to these two major groups of prokaryotes. So prokaryotes are just vastly more diverse than people thought. They broke into two really ancient divergent groups. Here you can see a rooted tree of life, and the rooting of the tree of life is not a trivial exercise because you don't have an outgroup, obviously, to life. You can't use rocks or minerals for that and get into how one does that, but it's not easy and very controversial. But the bacteria then are here, and here you can see the archaea and this analysis coming out sister to all the eukaryotes. So in this view here we see that actually the archaea are more closely related to the eukaryotes than the art of the other prokaryotes in the bacteria. So that was a real surprise, and there's some controversy about this that perhaps the archaea are that there may be genes that have been inherited by horizontal transfer from both of these groups that were invested in the original eukaryotes. The main point here is that they're just these two major groups of prokaryotes and the archaea are really cool because these include the extrema files, which literally mean the lovers of extreme conditions. File just means love, and this is basically a category that includes the majority of these archaea. And they break into three major groups, the halo files, which are lovers of salty conditions, of saline conditions. And if you fly over the San Francisco Bay and look down at the south end on the east side, you'll see these areas where these salt flats where salt is being harvested and you can see the archaea here imparting this red coloration. These are organisms that generally can't survive except under really high salinity, which would be at such a high level that a self-respecting eukaryote would have their DNA and their proteins denatured. It would be a total disaster, be fatal, but these organisms really require extreme conditions like this. And we can find these things growing in natural environments, for example, places like the Great Salt Lake, various salt flats out in the desert that are occasionally inundated after storms and the like. And that's a really interesting group. These are mostly aerobic organisms that require oxygen. The thermophiles are another major group, and these are even more fantastic really because these require such warm conditions that they would essentially boil alive or basically cook any eukaryote. And these are found in such places as these hydrothermic vents down in rift zones at the bottom of the ocean, these black smokers here where it can get up to 120 degrees Celsius, well over boiling. And these are basically primary producers down in this interesting ecosystem at the bottom of the ocean where we have some bizarre eukaryotes as well. And then we also find these things around actually volcanic vents and these hot springs situations and geysers like in the Yellowstone area around the Old Faithful Geyser Basin and places like that. And some of these guys are actually able to, they're autotrophs that are able to produce their own energy from hydrogen sulfide. So they're able to make use of chemicals that are poisonous to us. So these are really pretty amazing organisms. And then also there's a group called methanogens which live in the guts of ruminants in an anaerobic environment. Oxygen is deadly to these things. And they can, they help cattle and other ruminants digest cellulose and the like. So they're really important ecologically and they produce methane as a waste product. That's where the methane that we associate with cattle comes from in part. And interesting sort of circularity here is that these archaea, these extremophiles are actually responsible for PCR. So the DNA polymerases produced by some of these thermophiles are stable at boiling temperatures as I mentioned and that allowed PCR to actually be feasible because you have to denature the DNA during these cycles of DNA denaturation and then amplifying or annealing the primers and extending the primers. And it's originally thermobacillus aquaticus from Yellowstone National Park that was used to allow for PCR. So this archaea group was discovered because of the archaea. And without the archaea we wouldn't have discovered the archaea. So it's kind of an interesting situation there. Now taking the archaea aside, the remaining true bacteria are no less interesting in terms of their metabolic complexity. In fact they show every major mode of nutrition and metabolism even more so than we get in the archaea because none of the archaea are capable of photosynthesis, true photosynthesis where we're taking the energy from light and using that to fix inorganic carbon into sugars. That's only something that the cyanobacteria, this group here, has figured out how to do in a major way. There isn't another minor example but this is something that the cyanobacteria innovated, the capability for photosynthesis. And it's because of these cyanobacteria that we have an oxygenated atmosphere which arose about 1.8 billion years ago and allowed for the eukaryotes to really come into being. And these cyanobacteria are also really important for nitrogen fixation. You're probably aware that our atmosphere is mostly comprised of nitrogen gas but that nitrogen is unavailable to organisms and it's only through the action of nitrogen fixers like the cyanobacteria that we have nitrogen available which is an essential nutrient for organisms and it's easily lost from ecosystems by, it's easily leached out of soils for example so it's really critical functions here. And as we'll get to next time, the cyanobacteria are responsible for all of our photosynthetic eukaryotes essentially. That may sound a little strange but we'll get to that in good time here. Okay so I think that you've been already introduced to these concepts of major modes of living, the autotrophs and the heterotrophs and the ecology part. But I'll just review this briefly. Basically autotrophs are organisms that can generate their own food from inorganic materials or for non-organic, without the requirement of non-organic sources basically. So the photoautotrophs including basically the cyanobacteria that we've talked about so far. I just mentioned them, the chemoautotrophs I alluded to those, these are things like sulfolobus here which I realize kind of looks like a pepperoni pizza here but that's actually a cell. That's one of these archaea that can basically derive energy from hydrogen sulfide. And heterotrophs then are basically everything else that feed on either other organisms directly or on the products of those organisms, so organic substances. And of course we don't really understand exactly how life evolved, the original organisms but it's thought that the original organisms were heterotrophs and they were feeding on organic compounds that were produced by non-organic means but not by living organisms so in some sort of primordial soup. But subsequent to that after the evolution of autotrophs, the autotrophs which are going to be what we're going to really focus on in this botanical part of the course after the fungi, they really kind of created the conditions for life to exist here to a great extent. Okay so this again is just that five kingdom system in the context of now this three domain system. Now domain is not really a formal taxon, it's an informal group but these are good groups. Bacteria, the archaea being equivalent to the old Manera, all the prokaryotes here. And then we consider all the eukaryotes a single domain of life including these old four kingdoms that are no longer recognized as kingdoms per se. And this kind of lumping all of these groups into one big eukarya doesn't mean that those eukaryotes are less diverse than we thought before. It's actually that they're even more diverse and more complex in their relationships and that this is a vast oversimplification here of the relationships of eukaryotes to just put them into those four cubbies. And here you can see the overall tree of life and sort of well it's rooted here but it's laid out in sort of an unrooted general perspective with the archaea here in pink. These are those extremophiles and relatives. The true bacteria including the cyanobacteria that I mentioned that are photosynthetic. And here's all the eukaryotes up here in gray. And highlighted here are the major terrestrial multicellular groups that occur on land. The fungi, the animals, and the land plants. You can see that they're just little twigs in this big eukaryotic branch of life and that they're not very closely related to one another. In fact, based on their relationships it looks like they've each independently been derived from unicellular organisms. So multicellularity has arisen multiple times in each of these groups. I mean it has arisen independently in each of these groups. So you might wonder about viruses. I mean they're clearly critically important in medicine. I mean human health. They clearly evolve very quickly. They have nucleic acids. They have DNA or RNA. But they're inert unless they're in the presence of the living cells of one of these groups. And unfortunately they don't have very much DNA typically. And it looks like they've inherited their DNA in many cases by horizontal transfer from their hosts. And so these are very difficult to actually analyze in the context of the rest of the tree of life and figure out how they evolved. One thing we can say is that they are mobile genetic elements essentially. Comparable in a lot of respects to plasmids that live inside bacterial cells. Or transposons that live across basically all of life. And they may have their origins from such things as plasmids or transposons. But we're not sure. And they may have various different origins. So they're sort of left out of this picture. But we're not considering them unimportant. They're just difficult to include. Okay so now I want to just give you a general perspective on the organisms we're really going to focus on for the rest of the semester. So first off we're going to talk about the fungi as I mentioned here. Which used to be called plants. Nowadays people that study fungi are called mycologists rather than botanists. Mycology is the study of fungi. And some botany departments that still exist usually include mycologists. For example, our plant and microbial biology department includes a couple of mycologists there. So this Linnaean or Aristotle, you know, holdover of ancient Greeks is still seen in our departmental organizations. And then the so-called algae, which are basically marine or aquatic, typically marine or aquatic photosynthetic organisms. You can see that they fall out all over the place. That they're not a monophyletic group or a clade. And that the algae are much, much more widely scattered in the tree of life than anybody guessed prior to this molecular biology revolution back in the 90s. But as we'll get to next time, they're actually in some regard more closely related than they appear based on this tree. So that's when we start talking about the origin of photosynthesis next time. But just keep that in the back of your mind. And then finally, the things that we can all agree are actually plants, the land plants, the true green plants. These are that occur on terrestrial habitats. These are a natural group, a monophyletic group that we'll be talking about for most of the semester. And you can see that they're closely related to some, but not all of the algae. Okay, so let's focus in on the fungi now. This is going to be the topic for the rest of the lecture today. And we'll spill over next time into talking about them in terms of their ecological importance. But you can see that the fungi are really distantly related to the land plants, the plants in the strictest sense. And that they're actually, and I already mentioned that they've independently evolved multicellularity relative to the plants and the animals actually. But you can see they're quite closely related to animals that they're actually much more closely related to animals than they are to plants. And really, we should be including fungi in zoology departments if such departments still existed rather than botany departments. And that was a really major surprise. But there are some things in hindsight that make sense about that. And actually the fungi are more closely related to animals than to any photosynthetic organism. And neither the animals nor the fungi show any evidence of having ever had plastids, ever had any kind of photosynthetic apparatus that they may have lost. There's no evidence that that ever was the case. And they share a common ancestor based on fossil and molecular considerations about a billion years ago. Which sounds like a long time ago, but eukaryotes started really evolving almost twice that long ago. I mean, back almost two billion years ago. So that's not really all that long ago in the overall history of the eukaryotes. And that's reflected pretty nicely in this tree. So let's focus now in on characteristics of the fungi. The fungi have some really amazing features that make them endlessly fascinating to everyone. The fungi, I think, are really fascinating to the lay public and everyone because they're so different from other organisms. And you can see they include a wide array of multicellular organisms. And there are also some unicellular fungi as well, the yeasts. And there are about 100,000 species of fungi that are recognized, that have actually been described. But they're probably vastly more fungi that remain undescribed and remain to be discovered. And that's especially true for the yeasts is unicellular fungi, which may include more than 100,000 taxa. There's only like 1,500 described, but then maybe like 150,000 yeasts that await description. So the yeasts may actually outnumber the multicellular fungi. But there's not a lot of morphology to go on there to describe them. Okay, in terms of major fungal characteristics then, of course they're eukaryotes. They have membrane-bound nuclei in mitochondria, but no plastids. They don't have any evidence of having ever been photosynthetic. Their bodies are non-motile. Of course, this is one of the reasons they were considered plants back in the old sense. I should say their main adult bodies are typically non-motile. There are some exceptions. And that's one of the things that I think you may have already found out if you took 1A and talked about animals there. When you start talking about the diversity of life, there are always exceptions to the rules. But we're going to focus on the general... Oh, motile just means the ability to move. Yeah, sorry, be able to move around freely. Thanks for asking. And they have a filamentous type of body, and that might strike you as weird if you've seen mushrooms. Those seem like big solid objects, but they're actually made up of filaments, discrete filaments that are all interwoven, that are weaved together. And we call these filaments hyphae, or that's actually plural, a hypha would be singular. And these make up together what's called the body of the fungus, the mycelium. Okay, so that's what we call... this refers to body of fungus. That's what that literally means. And these are heterotrophs. They need organic carbon that's been fixed by some other organism, but they can't actually engulf it. They don't have a way to actually swallow big chunks of organic material. They aren't capable of phagocytosis, like an amoeba, to surround something and digest it. They have to actually enzymatically degrade organic material outside their bodies. They have to basically exude enzymes into their environment, break down that material, and then absorb it through their hyphae. So they have an absorptive mode of nutrition. And they actually do have cell walls. Now remember, animals don't have cell walls. All the eukaryotes have cell membranes, but only certain eukaryotes have cell walls, which are outside the cell membranes. These impart some rigidity, rigidness to the cells. This is one of the reasons that they were considered plants, is that plants also have cell walls, unlike animals. But these cell walls in fungi comprised mostly of chitin, which is the substance that makes up the exoskeletons of arthropods, like insects and crustaceans. So fungi actually, as one of their major constituents, they share a lot with the arthropods, which you probably didn't realize, but that's a pretty interesting similarity there. Unlike in plants where the cell walls are made up of cellulose. Now both chitin and cellulose are complex carbohydrates, but they have very different composition, and it's a real fundamental difference here between plants and fungi. Also the fungi store their carbon as a complex carbohydrate like plants, but in plants they store their carbohydrates as starch. Whereas in fungi they store it as glycogen, just like we do. So they share with animals this storage substance of glycogen. So that's another interesting similarity with animals, actually with all animals here as opposed to just some here. Okay, the life cycle of fungi includes spores, and in this regard they're similar to plants. Plants also have spores in their life cycles, and that's one thing that has been pointed to as a botanical, or plant-like feature even though it's not diagnostic of a close relationship with plants. And I already mentioned that they're both unicellular and multicellular. Okay, so any questions about characteristics of fungi? We're going to get into more of that in a second here. So here we see some fungi, hyphae. Here you can see an enlarged piece of the mycelium, where you can see these individual filaments making up these, I mean I'm sure you've seen this sort of thing on moldy food and such, and it looks pretty disgusting when we're looking at it just with our naked eyes, but when you get down to the microscopic level it's incredibly neat. And as I mentioned these hyphae are, well I don't think I mentioned their tubular filaments, and they grow from their tips. They have a really high surface area to volume ratio. The importance of that is that they can really come into contact with their environment very efficiently. There's a lot of surfaces in contact with the environment. That's critical because they have to digest their food outside their body, and so in part so they have this contact, their surface area to volume ratio is crucial, enhances their absorption. And you can see that the mycelium is extensive in the case of some of these macro fungi underground. What we see on the surface is just the tip of the iceberg. The vast majority of the mycelium is not the fruiting bodies where the spores, the sexual spores are produced, but the under usually what's in many of these terrestrial fungi, the subterranean part of the organism that's in contact with substrate that they can digest. They're just getting their fruiting bodies here up into the atmosphere so they can disperse their spores. I mean teleologically speaking that's the end result of that. Okay, and here you can see the development of the fruiting body of a typical mushroom. And this is obviously not at a typical rate here. This is accelerated greatly but I want to make the point that the fruiting bodies of fungi can develop incredibly fast. So when they go to produce sexual fruiting bodies like this, they really invest a huge amount of their energy in this and it can happen in a matter of hours that you can see the emergence of a fruiting body. So it's basically an overnight phenomenon and I think you've probably maybe seen that in your own experience but it's a pretty amazing capability of fungi. And here just we see a little bit of detail of the fungal hyphae and there are a couple of major types of hyphae that we see. These break out phylogenetically. So there are certain major groups of fungi that have this type and other major groups that have this type. So this is actually helpful to understand relationships of fungi to one another. So there's one type called senocytic and this is basically where the filament is completely open inside. There are no partitions or septi that break up the hyphae into cell-like units. So we have an open cytoplasm inside the hyphae and we have the nuclei in here not separated from one another by cell membranes. The alternative to that are these septate hyphae where you can see these septi that do break up the hyphae into partitions but I don't know if you can see it from the back of the room but there's a little hole inside these septi in the center of these partitions that allow cytoplasm to move freely through. So they do have some partitioning of larger parts of their cells like the nuclei here but cytoplasm can move freely through here and so the hyphae is still capable of rapidly mobilizing resources to growing places. For example, if they're going to produce a fruiting body they can shunt resources quickly to different parts of the hyphae. We don't really have cells in the typical sense in fungi. It's a different kind of situation really. You can think though of each of these partitioned off areas as cell-like. They are cell-like in a sense and we'll get more to that shortly. But fungi are weird. They just face it. They're not like you and me. They're very different and not like plants in this regard. They really do have an unusual biology and they're not all a bunch of decomposers like you might have heard in high school biology. We obviously know there's some really horrendous parasites as well. They are parasitic on living organisms in part but they're actually even some predatory fungi. It's probably hard to realize that a fungus could be a predator, an active predator, but there are some of these specialists and this one group of Ascomycetes will get to that part of the fungi later. It's the most diverse group that actually produce these hyphal loops that can actually act as nooses. You can see here a hapless nematode that's unfortunately trying to get through one of these hoops and now it's constricted around it and it's digested then by the fungus. There are some really bizarre innovations there. They're not just devious. The fungi are not just doing things to other organisms that are negative. They also have some really important in fact absolutely crucial positive interactions with other organisms and this is the one that's really fundamental to basically our survival as well as the survival of most plants and that's what's called the Mycorrhizae. Mycorrhizae literally means fungus root. So it's an association between a root of a plant and fungus and it's a mutualism. So it's a type of symbiotic association that's actually positive to both partners. Remember mutualism is both partners benefit not just one like in a commensalism. This is a mutualism and what you can see here is a fungal hypha that's in contact with root cells of a plant here and what the fungus gets out of this association with these plant cells is that it actually gains carbohydrates. It's getting food from the plant and that might seem like a bad thing for the plant but the plant's gaining inorganic minerals and some really crucial ones like nitrogen and phosphorus that are difficult that can be limiting in the environment that the fungus is really efficient at absorbing and it can also it's very efficient at absorbing water as well. So the plant gets a lot out of this association and we know that because if you prevent this association from forming in plants they do much more poorly in most cases. There are some plants that don't need this but the vast majority of plants need this kind of an association and there are a couple of types of these mycorrhizae. One's called ectomycorrhizal, ecto just referring to it being outside the root. So these are fungi that don't actually penetrate the individual root cells. They just cloak the outside of the root and their hyphae will penetrate between the cell walls but they won't go inside of a cell wall. So you can see here the different cells of the plant root and this is the hyphae. You can see they've intruded in here but they're only going in the intercellular spaces between the cells and they're not actually penetrating the cell walls. And we see these type of fungi which is a special group set of lineages associate with the roots of trees in temperate or boreal environments. Non-tropical trees, both conifers like pines and spruces and things like that as well as hardwoods like birches, et cetera, oaks and other flowering plant trees in temperate regions. Okay, so those are the ectomycorrhizal fungi. Now the vast majority of plants have this type of association. So all the herbaceous plants that don't produce wood, herbs and a lot of tropical trees have this type of association called an arbuscular, well it's an arbuscular mycorrhizae formed from arbuscular mycorrhizal fungi. Remember the association between the plant and the fungus is called the mycorrhizae or mycorrhizae singular and we call the fungi by that name mycorrhizal fungus because only particular fungi will have these types of associations with plants. And here you can see that the fungal hypha not only goes in between the root cells of the plant but also penetrates the cell wall. So here you can see this weird tree-like branching pattern of the fungal hypha where it's coming into contact with the cell membrane and you can see this really dense area here where these dendritic or tree-like branching patterns of the fungal hypha are in contact with the actual cell membrane of the plant. So they penetrate the cell wall and then they're covering the outside of the cell membrane and they're not penetrating the cell membrane of the plant cell. They're not puncturing it, they're just covering it and so they have a lot better contact area with the plant and there's a lot more surface in contact here for transferring substances. So that's the more common association and we see this in this type of association and more than 80% of plant families including some of the earliest diverging plant families were probably critical to the original colonization of land by plants, of terrestrial plants. And so this particular group is actually just a few, there's only a couple hundred species of these types of fungi that we know of today but they're really important. And here you can just see a cartoon of this tree-like dendritic pattern of the fungal hypha and it's sort of, it hasn't punctured the cell membrane here. You can see the cell membrane of the plant root just running along the outside there. So it's just sort of like sticking its fingers into a sort of cushion-like situation here where it's not puncturing but just getting in contact. Okay, so a little bit of time left. I just want to introduce you to the five major groups of fungi. Four of these we actually recognized in the past but one of these we didn't tell DNA evidence. And you can see that the fungi form a monophyletic group. So here's the root of the fungal tree right here. It's laying on its side and these are the five terminal groups with examples out here. We have two major clades of the big macro fungi that produce these big fruiting bodies that are sistered each other, the ascomycota and the basidiomycota. These being the true mushrooms and these being the sac fungi. I'll show you some more examples in a minute. But these are the ones you're probably familiar with. And then I'll talk about these in a moment here. This includes most but not all the organisms that have been called fungi in the past. And you're going to see some things in lab this coming week that are things we used to think were fungi but turn out not to be. But they have kind of similar lifestyles. So here's the sister group, the catridiomycota. These are organisms that have been called kittrids. That's the short hand name. And there are only about a thousand species of these compared to like 65,000 of these and about 30,000 of these. So really small diversity. But they're very interesting because they're one of the early diverging lineages here. And it was questionable whether they were even really fungi in the past but the molecular data really nailed that down. And here you can see some of these kittrids. They're really interesting because they're the only group of fungi that has spores and gametes that can actually move around with flagelli that have a single flagellum, whip-like flagellum. And in that regard they're really similar to some of the close relatives of animals in unicellular forms I should say. This whip-like flagellum is something they share with a common ancestor with the animals. So in the broad sense this big fungal animal group are called the unicons which is not a name you have to know but it means basically having a single whip-like flagellum. And we see that in these kittrid zoospores. And here you can see a little animation or it's not an animation this is actually real life. You can see one of these swimming zoospores and they can really get it on. They can really move fast. You can see them moving in this. You have a hard time keeping them in the field of view under a microscope. And here you can see they're being exuded out of the tip of this sporangium here. There's one being exuded out and as soon as they're released they take off top speed. And then they can settle down onto the environment, produce these hyphae and then a sporangium. So some of these have a really simple life cycle. Others produce big filaments. You can see one of these here. This is Alamyces. And the kittrids are really important ecologically for a number of reasons. They're in the soil. They're important decomposers. They're in aquatic situations. They're important there. Some of them are important in the guts of ruminants like I mentioned the methanogen back here or archaea. Some of them are important in the digestive tracts of ungulates. But you probably have heard about them if in any regard because they're one of the main factors in amphibian decline worldwide. And this wasn't a phenomenon that we knew about until fairly recently, over the last 10, 20 years, this phenomenon of catridiomycosis, this kittrid infection of particularly frogs and toads, has led to the extinction and rapid demise of lots of neurons worldwide. And it's a really serious disease. It's spread into California and other places familiar to us. And it's been a huge problem to organisms that are already having plenty of trouble. So these can be a really aggressive pathogenic disease-causing organisms. Okay, so we're out of time, but next time we'll get into the rest of these fungi. Talk a little bit about their life cycle. So happy Halloween. See you Monday. We're in office hour.