this lecture is about biological classification how we group living organisms together based on shared characteristics it's important to understand how we do this and it's important to realize if you know the biological classification of an organism and you know what the shared characteristics are of that group that tells you a lot about that organism this subject is called taxonomy it comes from two greek roots taxes which means arrangement and nomia which means a method so this is a method of arranging living organisms again based on shared characteristics this method of classifying living organisms was developed by a swedish botanist in the 1700s and his name was carolus linnaeus and it's important to know his name because you'll often hear this called linnaean classification he is who developed this method of classifying living organisms based on shared characteristics and there's a hierarchy of classification with some groups including more individuals and then getting more and more specific all the way down to what we call a species of organism of course back in linnaeus time this was all based on observable characteristics now we have dna analysis which allows us to really look at who's very closely related based on very detailed shared characteristics of their dna the most inclusive category of classification is what we call a biological domain so these are the three biggest groups of classification of organisms there are three domains in biology domain is fairly new on the scene when i was in college we didn't have domains we started with the next level down which is kingdom now domains are these big inclusive groups the three domains are bacteria archaea and eukarya in this class we really spend the most time talking about the domain eukarya this includes the organisms you're probably most familiar with those are the plants animals the fungi and the protists that's not to say that most organisms are in eukarya those are just the ones you're probably most familiar with i'm not going to spend time today talking in detail about each of these domains and what they have in common we will do that later in the semester but domain are these big groupings of organisms that have shared characteristics but really include the the largest number then within each domain we have kingdoms then with e in each kingdom there are phyla so singular of that is phylum and then with each in each phylum there are various classes then order family genus and finally the most specific level of classification which is species so species and specifics sound the same there's a reason for that those are from the same root word and they both mean something very specific to be the same species you have to be able to breed and produce fertile offspring so this would be the least inclusive level of classification whereas domain is the most inclusive level of classification it's important to know this hierarchy of classification and biology there are a lot of mnemonic devices for remembering this so if you just look at the first letter of each d k p c o f g s the one i learned in school didn't include domains if it's not really useful now but a modification of that is dear king philip came over from great spain i've also heard do kangaroos prefer cake or frosting generally speaking so you can look on the internet for one that makes sense to you that can help you remember i'm going to give you an example of classification or this hierarchy i'm sorry i have to get my piece of paper so i don't skip anything here um i'll do human classification first and then i'll do domestic dogs so you can see examples of this so again domain kingdom phylum class order family genus species do kangaroos prefer cake or frosting generally speaking i think i kind of like that one best so let's look at humans humans are in the domain eukarya which means that they have a membrane around their dna and they have membranous cell organelles they are in the kingdom animalia so humans are animals they are multicellular they have movement a lot of other shared common animal characteristics within the kingdom animalia are various phyla including the phylum chordata the chordates have a notochord a dorsal hollow nerve cord a postanal tail some other shared characteristics within the phylum chordata our various classes including the one that we belong in which is the class mammalia we are mammals we have fur we feed our young milk some other shared mammalian characteristics and within the mammal class there are various orders and we are in the primate order we are in the hominid family amenity our genus is homo and our species is sapiens oops sorry about that typically we write the scientific name of a species of organism using the genus and the species name and we do this with a method called binomial nomenclature this means oops i put in binomial let's try this again okay binomial i said it right but i spelled it wrong binomial okay this means two names and this means a naming system this is a two name naming system in which you use the genus and the species and they are written a very specific way and i'm going to talk about that real briefly and then i'm going to go back and do the domestic dog so you can compare that to the human classification the way you would write the scientific name for humans is the genus name comes first and it's always capitalized so capitalized first letter only of the genus name and then the species name follows but it's all lowercase no capital if this was typed it would have to be in italics so if typed must be italicized oops that's a c isn't it i'm really not in my best spelling game today must be italicized in italics if it is handwritten as this is it must be underlined and it must be underlined each word separately like this so if handwritten genus and species each underline separately also if you were writing a scientific paper and you used homo sapiens multiple times after the first occurrence you wouldn't write the genus name completely out anymore so this gets a little more tricky if you read a scientific paper or a textbook you'll see this so the first reference we would write it just normal with the full genus and species name separately underlined if it was handwritten or italicized if it was typed and then the next reference we would just write h sapiens oops and the whole thing would be underlined and it would be written like this with the period after the h so h period sapiens with the whole thing underlined or the whole thing italicized if it was typed you won't be doing that in this class but i just wanted you to know if you ever see that written that way that's why that is okay binomial nomenclature so if i told you that the species name of something was lupus and the genus of something was canis the correct name to write the scientific name of that organism is going to be genus first so that would be canis species next lupus canis has to have a capital first letter and since i'm handwriting it i need to underline each one separately if it was typed it would be italicized this is a dog this is your dog as canis lupus so let's go back now and write domain kingdom violent class order family gene the species for dogs so you can compare so dogs are also in the domain eukarya they are also in the kingdom animalia they are animals they are not plants fungi or protists they are also chordates and they are also mammals but they are not primates so this is where we're getting more and more specific by the time we get to order they're in the carnivore order order they are carnivora and they are canines they're in the family canada and their scientific name is canis lupus domestic dogs actually have a subspecies canis lupus includes all wolves and domestic dogs so they actually have a subspecies for domestic dogs and it would be written like this canis lupus familiaris that is actually a subspecies not all species have subspecies but in this case wolves and dogs can interbreed but they thought it was important to point out that this particular subspecies is domesticated and has some slightly different characteristics than a wolf but all domestic dogs came from wolves through selective breeding let's look at some examples of scientific names and what they tell us about these organisms starting with the guy at the top what is the common name for that organism right that's a bald eagle does that bird have a bald head no he does not he has white feathers on his head let's look at the scientific name for that bald eagle the scientific name for that bald eagle is halleatus leucocephalus so let's just start with leukocephalus that means white head luca means white and syphilis means head he's a white head not a bald head right so already the species name tells us more about that eagle than the common name and then you can see salt eagle is also very descriptive so in this case the scientific name really tells you something about that organism and that's pretty typical a lot of times a genus and species name are using greek or latin to tell you something descriptive about that organism and i think that's really cool a lot of times you can just look at that name and decipher it and it tells you something about that organism before you can before you even see it you could predict oh well this must be an eagle and it must have a white head sometimes we name organisms after people sometimes they're named after the person who discovered this new species of organism in this case um there were um a lot of ferns that were classified together a new genus of ferns was discovered with 19 different species and they were all given the genus named gaga and then one particular species was named specifically after her using her last name so you can see the scientific name of this fern and it's named after a person not the person who discovered it but somehow this fern reminded the scientists of an outfit that lady gaga had worn so that's kind of a funny one then finally this last picture i want to show you the importance of understanding the differences and the similarities between organisms based on how they're classified so both of these organisms are both in the phylum arthropoda so they'd be domain eukarya kingdom animalia phylum arthropoda one of these is an insect and one's an arachnid a lot of people call these bugs in general which is there's only one specific group of insects that are the true bugs not all insects are even bugs but these two organisms have some shared characteristics okay that's why they're both in the phylum arthropoda but they're also really different in a lot of ways you can see this insect three body segments it has an abdomen a thorax and a head whereas this one has two body segments this is called a cephalothorax and an abdomen you can see that this one has antennae where this one does not these are called petty pelts they're not actually used the same way that antennae are used they're very different in fact insects have six legs whereas this arachnid has eight legs and there are other differences as well they both have an exoskeleton which is part of what makes them together in the phylum arthropoda and obviously they have some similar characteristics but they're enough different that they are put into two different classes and then within each class they're obviously going to be different orders family gender and species so that is my talk on biological classification the next lecture is going to be on evolution in particular natural selection