Taxonomic Systems Section 9.1

The More Specific The Better READ ONLY The More Specific The Better An eyewitness describing a getaway vehicle could say the following: The colour The model The year The license plate number The best evidence of all!!

Classifying Organisms One purpose of a classification system is to allow the accurate identification of a particular organism. The second purpose is to recognize natural groupings of living things.

Taxonomy The practice of classifying organisms is known as taxonomy. Founded nearly 300 years ago by a Swedish botanist named Carolus Linnaeus. He used simple physical characteristics to identify different species and organize them into groups.

Hierarchy of Groups READ ONLY As members of the animal kingdom, the bee, shark, horse, dog and oyster have certain things in common. On the other hand, these animals are obviously not very much alike. There are different degrees of similarity among animals. A horse is more like a dog than like a shark.

Taxa To distinguish such different degrees of similarity between organisms, each kingdom is subdivided several times into a series of progressively smaller groups. Each group is called a taxon (plural taxa). Kingdoms are the largest and most general taxa. Species are the smallest and most specific taxa.

Organisms in this taxon Example Organisms in this taxon (READ ONLY) Kingdom Animalia Bee, frog, shark, horse, oyster, dog, cougar, lynx, bobcat Phylum Chordata Shark, horse, frog, dog, cougar, lynx, bobcat Class Mammalia Horse, dog, cougar, lynx, bobcat Order Carnivora Dog, cougar, lynx, bobcat Family Felidae Cougar, lynx, bobcat Genus Lynx Lynx, bobcat Species Lynx canadensis Lynx rufus Bobcat

Naming a Species Linnaeus’s two word method: Felis domesticus (the house cat). Many of these names are based on Latin or Greek words. These names often reflect characteristics of the organisms, or in other cases, the names are given to honour a fellow scientist or historical figure or a location where the animal lives.

Binomial Nomenclature The system of using a two-word name for each species is called binomial nomenclature. The first word: name of organism’s genus The second word: identifies the particular species. The first letter of the first word is capitalized. The entire name is in italics. There may be several species with the same genus name.

Genus: Canis Canis lupus: wolf Canis latrans: coyote Canis familiaris: domestic dog The fact that the above animals have the same first name tells you that they are all in the same genus of dog-like animals and are very similar to one another.

Common Names Why not just use common names like cat? Common names are not precise. There are many different species of cats: wild cats and domestic cats. In addition, people in different regions may use different common names to refer to the same species. For example: puma, cougar and mountain lion are three different names for the same animal.

Misleading Information Common names can give you misleading ideas about the basic characteristics of an organism and the group in which it should be classified. Should shellfish, starfish, jellyfish, crayfish and catfish all be in the single group, fish? Biologists place each of these members of the animal kingdom in a separate phylum.

Where do we fit in? Taxon Humans Kingdom Animalia Phylum Chordata Class Mammalia Order Primata Family Hominidae Genus Homo Species Homo sapiens Chimpanzee Animalia Chordata Mammalia Primata Hominidae Pan Pan troglodytes Pan paniscus

Dichotomous Key Goal of a taxonomist: identify an organism at the species level. Dichotomous key: an identification tool consisting of a series of two-part choices that lead the user to a correct identification.

Example 1. a. Organism is microscopic...................................PARAMECIUM. 1. b. Organism is macroscopic............................................go to 2 2. a. Organism is a plant.....................................................go to 3 2. b. Organism is an animal.................................................go to 5 3. a. Plant has a woody stem..............................................go to 4 3. b. Plant has a herbaceous stem.................................DANDELION. 4. a. Tree has needle like leaves.....................................PINE TREE. 4. b. Tree has broad leaves............................................OAK TREE. 5. a. Organism lives on land................................................go to 6 5. b. Organism lives in water...............................................CLAM. 6. a. Organism has 4 legs or fewer......................................go to 7 6. b. Organism has more than 4 legs...................................ANT. 7. a. Organism has fur........................................................go to 8 7. b. Organism has feathers................................................ROBIN. 8. a. Organism has hooves.................................................DEER. 8. b. Organism has no hooves............................................MOUSE.

Homework Dichotomous key handout p. 331 #1-5