>> Hello, students. This is Plants and Animals of Southern California. This is the first day of class. And throughout the semester, we're going to be talking a lot about species. So I thought just to break you in and give you an opportunity to taste what the class is about, then I should start my thinking or start revealing my thinking about what a species is not. So we're going to use these, you know, we'll be knocking around the word species a lot. We'll be naming lots and lots of species. And I think that in our common usage, our common language, our vernacular, we use the word species and we speak about species in ways that kind of suggest a lot of things about them that are not really exactly true. And so, I wanted to kind of start this out by suggesting that species is a word. It's kind of Democrat, like if you looked it up in the dictionary, there would be multiple definitions. Okay, so species, I think is a word that has lots of different meanings, that are kind of subtly different. And not only that, the meanings of the word have kind of developed historically over time. So 300 years ago, people were naming species as though each one was like an idea of God. That they each, each one was an idea kind of in almost the same way that like a triangle is an idea, right? Like a triangle is an idea and there is some perfect triangle that doesn't exist in the real world but that exists in your mind. And so, I think back then, people were thinking that this is an imperfect sycamore but it represents a perfect sycamore that existed in the mind of God. And you can think of that as kind of platonic thinking. So it's in reference to Plato's Allegory of the Cave which you may have read at some point where he kind of distinguishes that which exist in the ideal world from that which exists in the world that's actually manifest. So that might be a starting point. And I think that actually, when we speak about species, that same type of notion could be kind of floating in the air even though I don't think that species are like that at all. Even though I kind of use the same language that would have been used 300 years ago, I mean a lot less by it now than I might have if I, you know, were at the beginning of the Age of Enlightenment. Anyway, let's go back to the beginning of the Age of Enlightenment and think about that because that is sort of the founding of how we end up with all these names. So there was this guy Linnaeus who was a Swede and he had the big ambition of naming all the species. Of course, many of these species already had names. But he developed a naming system which we'll call the binomial system. It has two names. The first name is the genus name and then the second name is an adjective that modifies the genus name. So like Homo sapiens. Homo would be the genus, sapiens would be the wise ones. Sapien means wise man. So we're like the wise men, he thought. And this sycamore here is Platanus racemosa. So Platanus is the genus and there are several different species of Platanus that exist in the world now. And then racemosa is the Western North American species. So Platanus racemosa and you never use the word racemosa just by itself. It would always, you'd always put the whole, the whole binomial together or at least put P period to imply which genus it's in. So that's the binomial way of naming species. Now, there are, I've already talked about genus. So that's another category that's above the level of species. And if you think about it this way, you're going to have one species and it can be in one genus. Like Homo sapiens, we only have one species left. Presumably, we killed off Homo erectus. I don't know. But there were other species of Homo but they're gone. So there's only one species of humans, Homo sapiens. And that's one species and one genus. But then you could have Platanus. It has several species. And you could have many species in a genus. So for instance, I studied these flowers called penstemons and there's something like 280 species in the genus Penstemon. Now, genera are also grouped together in higher categories. So a bunch of genera together could be a family. Like you might have the family of grasses. There's lots of, lots of species of grasses. Thousands of species of grasses in this family of grasses. Or you could have the family of those flies that we took a picture of, the horsefly was in it. And there's lots and lots of species of horseflies in lots of genera in the horsefly family, the Tabanidae. You can often recognize a family because for animals, they often end in I-D-A-E, I think, I-D-A-E. And for plants, they often end in A-C-E, A-C-E-A-E. So Tabanidae, Tabanidae ends in I-D-A-E. And the family of grasses is the [inaudible] A-C-E. It ends in A-C-E-A-E. Not all families end in those endings but a lot of them do, a great many of them do. Now, of course, you could also have a single genus in a family. It could just have one genus in it and it could have one species in it, right. So you could have a family that has only one species. It would be said to be monotypic, monotypic. And that goes back to when Linnaeus' time when you name a new species, you take a specimen. And you designate it as the type. So if I were to name a new species of moss then I find some of this moss and I think, "Oh, it's distinctive. It's different from all other mosses that have ever been described." And then I would name it something. So like I might name it North regensis. And I might put it in some genus that already exists. So say I put it in the genus Hypnum which are the mosses that might hypnotize you. So it would be called Hypnum north regensis. The distinctive Hypnum found in Northridge. Then I would take some of those specimens and designate them as types. And one would be the master type, the holotype. Then if anybody ever wanted to know what I meant by Hypnum north regensis, they could go back to that specimen and look at it and decide is that really distinctive from all other Hypnums and all other mosses? And should it be recognized as a good species? Or was Wilson crazy and just named a regular Hypnum, you know, like Hypnum centrali, that should be locked together with Hypnum centrali. And if it should be locked together, then my name, my name would become synonymized with the older name, Hypnum centrali. And that name would then no longer valid by those people who lumped it together. So this is kind of a, this is our first definition of species. You might think of it as the taxonomic species concept or the morphological species concept. What it is, is okay, so where were we? So morphological species are taxonomic species, and that's really what the community of taxonomists agree to recognize. It's not a very, it's not a definition that's very satisfactory but what it would be is a species would be something that is you recognize as different from other species. And it would be based on their traits. Like it would be something you could observe about it allows you to recognize it as different from a whole bunch of, from all the other species that are named. But see, that's not really particular to the rank of species. Right, because we might have, for instance, you might have heard of subspecies. So subspecies would be things that you could also kind of recognize as different from other subspecies. And genera, of course, would be something that you could recognize as different from other genera. So just the fact that taxonomists recognize it as different doesn't really give you insight into how come taxonomists recognize it at the species level because there's all this different levels that exist. There's the genus level and the species level and the subspecies level. And it gets worse than that because people realize, oh, there's all, you actually might want to recognize some groups within a genus that are not so low as the species. And these are called sections maybe. So you could have like three genera and then in this genus, you might have two sections. And in this genus, you might five sections. And in this genus, you might have one section. Then within these sections, and I think I'm up to nine sections at this point, then you might have 20 something species scattered amongst these nine sections. Okay, but that's not even good enough, right? Because then you might realize, oh well, so one of these sections really could be split into subsections. So there's all these different ranks that people have come up with. Linnaeus' original ranks, you probably heard of, so species, genus above species, family above genus. Order above family so like the orders of insects. Class above order so like insect is a class. And then phylum above class. So that's like the original ones. Oh and kingdom at the top. There's kingdom at the top. So those are the original ones. But then, people start intercalating things, you know. Like they have to come up with subgenus and section and then subsection. You know, and it keeps on getting broken up. And then even below, even below species, you can start breaking things up into subspecies and stuff like that. So the ranks are these kind of fuzzy things that taxonomists have come up with over the last 300 years to sort of help you along. And it's pretty much the ranks are pretty much a non-evolutionary concept. Like there's no evolution that you have to recognize in order to come up with these ranks or categories or to recognize species because in fact, it was done before Darwin and it didn't really change after Darwin, at least not until very, very recently, the ranks, that is. And in fact, in the Origin of the Species , Darwin spends a whole chapter talking about how the differences between closely related species have all sorts of insensible gradations of closeness. So if you take a bunch of species, a bunch of pairs of species that are each other's apparently closest relatives then they can be very, very close or a little bit farther apart or a little bit farther, more farther apart or a little bit more farther apart, it's just every possible level of distinctiveness exists in nature. Now, we Homo sapiens, we're a very distinctive species. But this Platanus racemosa is not a very distinctive species. Like its closest relative which lives on some other continent looks a lot like it. Very, very similar to it. Okay, so the lecture is really about what a species is not. And I think one of the first things that you want to realize that a species is not is a species are all equally distinctive from their nearest relatives. I'll say it again. Species are not all equally distinctive from their closest relatives. There's every level of distinctiveness. So that was, that's probably one big way in which a species is not what it kind of appears to be. It's not some unit in nature that is separate from all the other units in nature in kind of an equally different way. So, well while we're on a roll on that, I think there are some other things that we also might recognize about species. So these species presumably, they exist on the tree of life. Like the tree of life gave rise to all the individuals and then some of them are in some species and some of them are in other species. Now, you might think that species are little pieces of this tree of life that are whole and complete. And we do try often, recently, like in the last few decades, to make higher groups like genera and families. We try to make them whole complete branches of the evolutionary tree. It's been really hard because the taxonomy that was handed to us from Linnaeus that was handed, that was handed to us when I was born, like the taxonomy that existed when I was born, it was not a taxonomy that took into account the tree of life and tried to recognize each taxonomic group like each genus and each family as a whole complete branch. Very often, those taxa that existed and were recognized when I was born, they were part of a branch and out of that hand, a twig had arisen that represented a different group. So you would have all of these species here that would be, say, recognized as one family like say the family of great apes and then out of this family of great apes, another family could arise, the family of humans. And so you have a great ape family and then you'd have a human family. But you see, in terms of the evolutionary tree, that means that the great ape family contained within it the human family. It had families within families which doesn't make any sense. Like that's not the way Linnaeus set it up. Linnaeus set it up so that a species could only be in one family and it could not be in another family. So if we are in the family of humans, which was called the Hominidae then the Hominidae could not be inside of the family of great apes. So what's happened since I was born, probably since you were born, is that we've had to undergo a massive reorganization of the taxonomy. In order to try to make these groups be what's called monophyletic. A monophyletic group is a group that contains all the descendants of a common ancestor. So all of these organisms are descended back to a common ancestor and the group contains all of those descendants of that common ancestor, not just some of them. That's a monophyletic group. And it's in contrast to a paraphyletic group. A paraphyletic group would be a group that contains some but not all of the descendants of a common ancestor. So a classic paraphyletic group would be the class Reptilia. So if you've ever heard about reptiles from when you were a little kid, the reptiles would include turtles, lizards and snakes, crocodiles, maybe some stuff that's extinct, dinosaurs. But if you recognize that group as, on the tree of life, then you'd have to say based on all the evidence that we have, that birds arose out of that group. And then if you recognized birds at the level of class, birds as a class then that would make the reptiles paraphyletic because they would be all the descendants of this common ancestor of all of these animals except for the birds. And then actually the mammals are somewhat controversial too. So it would be except for the birds and the mammals. Like reptiles are everything that's got a nice eggshell except for the things that became birds and mammals. And certainly the birds, you know, like birds are descended from dinosaurs and dinosaurs were you know, deep in there with crocodiles and everything else. There's no way you couldn't break it up. So it turns out that the class Reptilia is, it's not a monophyletic group. And so the taxonomy is being revised to not recognize Reptilia. Instead, you have to recognize each of the little groups like squamate lizards and snakes is a group. The turtles is a group. And crocodiles, they have to be their own group. And then the dinosaurs, that's a huge mess, right? Okay, so -- So the families and genera that we will encounter, taxonomists are working hard to reorganize the classification so that they will be monophyletic groups. And because of this, a whole bunch of names are changing. Like names have changed since the time you were little kids to now and by the time you have little kids, the names are going to change again because we're trying to figure out what the tree of life is and then reorganize the classification to reflect that tree of life such that everything is a monophyletic group. Now, of course, not everybody agrees with this but I think that is the overwhelming kind of wave of research is moving in that direction is to try to recognize only monophyletic groups. But at the lowest level, at the species level, it's a little more painful than that. Because you could, you can and probably often do, have a very widespread species like for instance, Douglas fir. You might know Douglas fir if you're a carpenter. You know, you get these, you know, Douglas fir two by sixes and whatever that you build houses with. Now that's a very widespread species and out of that very widespread species, has come a local species that's a very narrow species geographically called the big cone Doug fir. And at least in terms of the morphological species concept, everybody would want to recognize the big cone Doug fir. It's got a number of characters that are distinctive and you'd want to recognize it. But then, recognizing that makes the regular Doug fir paraphyletic. The regular Doug fir is paraphyletic by virtue of the fact of excluding the big cone Doug fir. So here's another little hitch of what a species is not. The species, at least, the names that we're handing you, some of them are monophyletic and some of them are paraphyletic. So you can't assume that just because I got a name for something that the taxonomist that recognized this species are recognizing a whole branch, a whole twig of the tree of life. Now, another thing that a species is not, is not all species are equally old. So if you, if you were to have a really good fossil record then some species would go back in time just a little bit. And we have a whole bunch of those in Southern California. Species that have arisen, people have named them. They're nice distinctive species, at least at some level. But they don't have an ancient history. They probably don't go back more than a few million years, maybe three or four or five million years before they merge back to in with other related species. And then other species that we'll bump into are things that haven't changed for a hundred million years very much. They've been really constant entities in the fossil record and they are very, very deeply rooted in the tree of life. Like for instance, giant sequoia or gingko. You know, gingko biloba is supposed to make your memory go good? Yeah, so those species, they've existed for a long, long time without very much change. And so, a third way in which species are not what they seem is they're not all equally ancient. Some of them are really young and some of them are really old. A fourth way in which species vary from one to the next is in how much variation they contain within them. So humans, we seem to have a lot of variation within our species. Like humans look really different and I don't know if this is just because we're super sensitive to noticing that they're different. But if you have looked at humans from around the world, they, you know, kind of all look kind of different. You know, there's a lot of different, a lot of diversity within a species, within that species. On the other hand, there are some species that are very monotonous. But you see it everywhere you see them, they just sort of seem like they're the same thing. And so, the various species that we're going to see throughout this course, some of them are the ones that contain a great deal of variation that you would have to sort of, you'd be wowed by it. There's no way you could ever say even be, you know, like even have the feeling that they adhere to an essential look. And then there's other species that you will bump into that seem to be almost exactly the same, every, you know, every time you ever see it. So there's four ways in which species are not what I think you might think they are in just common usage of language. Like they have, they have this kind of arbitrariness to them that we need to be able to be a little bit aware of. And as the semester progresses, I think this will dawn on you more. Like you can understand it now in the abstract way. But as we start meeting species and I start giving you names and telling you stories about their history then it'll like be the waves that are crashing in on your mind and eroding away time. And this way of talking about species for time out of mind was certainly really strong 300 years ago. And I think that language still kind of carries through with us today. So I said that, I said that species is like a word in the dictionary that has a whole bunch of definitions. And the definition that I talked about is this kind of pre-evolutionary definition, the morphological species concept or taxonomic species concept. And it would be more or less a species is something that a taxonomist recognizes as distinctive by virtue of the fact that some of its characters differ from all other species. It differs in its character from all other species. And some people might, you know, insist on there being a couple of characters that it differs in or maybe three. Probably nobody would insist on four. And then, people suggest species and write them up and then it's up to future taxonomists whether they use it. If they find it useful and distinctive then they carry it through. So that's the morphological or taxonomic species concept. And that's the one that all these names are based on. But then we also use the word species in lots of other ways. So you'll commonly come across usage that suggests that species are communities of interbreeding organisms separated from other such communities. So that the species Platanus racemosa, it is a reproductive community where at least potentially, all the different individuals of Platanus racemosa could interbreed with one another and you know, hold - they're held together by those bonds of mating. And that they are distinct from other species because they don't or haven't in a long, long time interbred very much with those other species. So that's a biological species concept. And that's the so-called biological species concept. And I think it's very common when we talk about species in the abstract where we're not talking about particular names of species to invoke something about the biological species concept. Now, there are additional species concepts that exists. Another species concept that exists, I'll call the genealogical species concept. It's sometimes called the phylogenetic species concept. The genealogical species concept would have something to do with whether, not whether they can interbreed because maybe things can interbreed in the future if there's transportation of seeds from one continent to another. But whether they haven't interbred for so long that their genes have come to coalesce. That they no longer share with their sister species the -- or not very many of the genes that the ancestor gave to both of them. So this is kind of a mathematical concept like you could only do it in a quantitative way and if you actually wanted to apply it, you would need to have some gene sequences or something like that. But even in an abstract sense, without trying to apply it, we can start thinking of species as being things that have enough of an ancient history of commonality to be categorized or different from other related species. And that's kind of the distinction of rank because if it was just race then race is, they just blend into one another, right? They're not distinctive. You just move across the landscape and eventually, things are different but there's not anywhere any nice point where you could just draw a line. Whereas at some point, lineages on the tree of life have enough deep history so that they have a distinctiveness about them. So that's like a third really important definition of species and it's not important so much because of application. It might be applied but if so, only just now. It's more, it's an important way in which we speak about biodiversity. And we'll use that word species and you'll very often not specify whether I mean a phylogenetic species concept like the genealogical species concept or the biological species concept or the taxonomic species concept. You know, if people use the words completely interchangeably even though they have very, they have very different meanings when you really kind of get down to it. They're all about biodiversity so they're related topics. But the topics have changed a lot. Kind of like china and China even. You know, China is this porcelain stuff that you drink tea out of but it's also a country. And so the word china has several meanings in the dictionary. Now, species maybe hasn't gone quite that far but it's at least got as far as democrat and Democrat where if you capitalize it, it means a rather different thing than if you don't capitalize it. All right, well, that's all that I have to say about that.