 Hey, darlings, today, today, we get to start looking at what happens when evolutionary processes go crazy. Today is the first lecture in our series on the diversity of life. And hopefully, we could absolutely spend the entire course talking about the diversity of life. I would be delighted to do such a thing. What you're going to find is that we're going to talk about, you know, we're going to spend four lectures talking about different groups of critters, and you'll see that really, we could spend an entire course on each one of the groups. And there are courses out there on each one of these groups. Some of those courses you could even take here at our institution. So everything, we're going to do a little bit of an overview to get ourselves oriented to kind of how we're going to approach diversity of life. But really, all the details we're going to look at today come from single-celled critters. Now, there's lots of different kinds of single-celled critters. Some of them are considered germs. Germ is probably a term that we should avoid in this course because it isn't very scientific or specific. It doesn't tell us very much. And in fact, while this cartoon is rather humorous, I don't know, I think that these germs look like they have nuclei, which tells you what. They're not going to be bacteria because they have nuclei. So I don't know. That's, what we'll see is that there's a whole bunch of diversity in different kinds of critters. And some bacteria, some cells, single-celled critters with nuclei, which would then be eukaryotes, can cause diseases. They can be considered germs. So we'll just, we'll just enjoy this cartoon because it's kind of entertaining. This is an example of a single-celled eukaryote. Single-celled eukaryotes are called protists. And we're going to put them all into a giant cladogram. So let's go ahead and kind of think about what our cladogram is going to look like. I'm going to draw one for you because I want you to be really clear on the relationship, but we really have three primary groups here. We've got our bacterial group. We've got a group of our chians, and we're going to talk about both of these groups in detail today. And then we have a group called eukaryota, which is all eukaryotes. And I have a visual just to help you picture what are these things that you speak of. Well, our chians are basically bacteria. They are prokaryotes. We're going to have an entire talk on our chians. We're a little more familiar with bacteria and really take microbiology and you will not come out of that class thinking that all bacteria are the same. They are extremely diverse and we're going to spend, I don't know, three or four sections of this lecture just talking about bacteria, but we're a little more familiar with bacteria than archaea. But then what we're really familiar with are the eukaryotes, and the eukaryotes come in single-celled flavors, and those are considered protists. This is an example of a single celled, actually this is two different types of single-celled eukaryotes. And then of course we have holy multicellular madness, and diversity of eukaryotes. Plants are eukaryotes, fleas are animals, and they're eukaryotes, this is an invertebrate animal. Birds are vertebrates, they are animals, they are eukaryotes, here's a fungus, that thing is a eukaryote. Here's a sperm, because of course, I mean you can't talk about critter diversity without talking about sperm. Sperm are interesting because they're like their own little critters, right? Except they're what give rise to a multicellular organism. So sperm, like we're going to have some very interesting sperm conversations throughout this section, but they are considered eukaryotes and not protists. Okay, so let's draw ourselves a picture of, let's draw ourselves a cladogram that illustrates the relationship between these groups. And before I do, I want you to think about the idea that, yeah, you know what, there was a first cell at some stage in the game, and no, it didn't really look like this, but the first evidence of cellular life has been found on our planet. And after aging or what, finding the age of the rocks that contained the fossil evidence of cellular life, we think that the first living critters came about 3.6 billion years ago. So that's a chunk of change, you guys. Like we're talking a long time ago, and the question is, what did that thing look like? What did that very first cell look like, that very first population of cells, what did it look like? So you're going to draw about 50 billion of these different trees to orient yourself to the whole thing, and we're going to continue to add critters onto our tree. So I'm going to show you this little guy, Rat Herr. That's going to be my ancestor. That's going to be my 3.6 billion years ago ancestor that gave rise to everybody else, and it's going to be a cell. Like that's, we should be comfortable with that concept. And remember that a cladogram just shows you evolutionary relationships. So I'm going to show you how these guys are related. The first branch from that very long ago common ancestor of everything else branched into bacteria. And we are going to look at bacteria. The second branch, they got something. So of course that first population went through speciation and various evolutionary processes, and one group was bacteria, which really are pretty similar to what we think this guy was like. The other group got histone proteins. What are those? Histone proteins are proteins that DNA winds around in a chromosome. Remember DNA is just a string, a double helix string, and it winds around, to make a chromosome, it winds around these proteins called histone proteins. The histone proteins help keep the DNA organized inside a chromosome. Now, if you think of histone proteins being a derived characteristic, a trait that is possessed by all critters beyond this point, but not by anybody before this point, then that tells you dog pounds of a feather are archaea, that says archaea, and eukaryotes are, how can we say this? They are connected by the fact that they have histone proteins in common. Now we look back, remember, we look back on this and we go, you know, if they have histone proteins in common, it's more likely, we don't know for sure, but it's more likely that they shared a common ancestor that had histone proteins, and that they both branched off of that, rather than both of them developing histone proteins separately from each other. So this is the characteristic that links them, and then of course, what defines a eukaryote? This one's easy. Eukaryotes are defined by the presence of a nucleus. Eukaryotes are only eukaryotes if they have a nucleus, and I tell you, you know, there are some exceptions, for example, red blood cells in our bodies don't have nuclei, but that's because in their life cycle, they start out with nuclei when they were baby red blood cells, and then they lost them at some point. Now there's somebody that you're actually pretty familiar with that isn't on this cladogram, and go ahead and think about it, or cheat and look at the outline to see who we're going to talk about next.