Classification of Organisms Main Idea *****Chapter 14***** Students should be able to: * Understand why a classification system is important * Understand that there are a variety of ways to classify organisms * Understand the origins of our modern classification system
Why Classify? To study the great diversity of organisms on earth, biologists must give each organism a name. But, a universal naming system was needed to avoid confusion caused by regional names.
Why Classify? Taxonomy is the discipline of classifying and assigning each organism a universal name.
Early Naming Systems The first attempts to classify organisms was to describe the physical characteristics in great detail. This resulted in very long names like: Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.
Binomial Nomenclature This system, proposed by Carolus Linnaeus, is still in use today. It is a two-word naming system. Each species is assigned a two-part scientific name.
Binomial Nomenclature A scientific name is always written in italics (or underlined), and the first word is capitalized and the second word is lowercase. Homo sapien is the scientific name for humans. (or Homo sapien)
Binomial Nomenclature Homo sapien The first part of a scientific name is the genus. A genus is a group of closely related species. The second part of the name is unique to each individual organism or the species.
Binomial Nomenclature 8
Question? Do Ursus arctos and Ursus maritimus belong to the same species? No, they are different species.
Question? Do Ursus arctos and Ursus maritimus belong to the same genus? Yes, they both belong to the genus Ursus.
System of Classification The classification system is hierarchical, or consists of levels. They are, from largest to smallest, domain, kingdom, phylum, class, order,family, genus, species. Each level is called a taxon or taxonomic category.
The 8 Taxa (plural for taxon) Domain Did Do Kingdom King Kentucky Phylum Philip People Class Cross Climbing Order Over Over Family For Fences Genus Good Get Species Spaghetti Shot
The Human Species (Domain Eukarya) Kingdom: Animalia (Animal in Latin) Phylum: Chordata (Spinal Cord) Class: Mammalia (have mammary glands) Order: Primates (two mammary glands) Family: Hominoidea (bipedalism) Genus: Homo (man) Species: Sapien (wise, knowing)
Least Specific (least in common) Section Section 18Lea-118-1 Grizzly bear Black bear Giant panda Red fox Abert squirrel Coral snake Sea star KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Carnivora FAMILY Ursidae GENUS Ursus Most Specific (most in common) SPECIES Ursus arctos
The Classification Game!! With your partner In the following few slides, you will find 14 different organisms, each of them labeled with a letter. In your groups, write down two main classifications (example red/green) Then place the corresponding letters under the correct classification.
For Example These organisms have been classified by their color. Red Green
ARE YOU READY!
A B C D E F G H I J K L M N
One Possible Solution Plants Animals C G M A J???? B K D I E N F L H
Did You Have Problems?? There were actually several different ways to go about classifying these 14 organisms. You might have done color, shape, size, number of legs the possibilities are endless. You might have encountered one or two that really did not fit into either of your two classifications, what should you do when this happens? Make a new classification of course! And this is what scientist have done as well through the years.
Cladistics A phylogenetic classification system that uses shared derived characters and ancestry as the sole criterion for grouping taxa (Phylogenetic means evolutionary development or history) Cladogram: an evolutionary tree
Cladogram a diagram that shows evolutionary relationships among organisms based on shared derived characteristics. **Helps scientists understand how one lineage branched from another in the course of evolution
Derived Characters A unique trait of a particular group of organisms that appears in recent parts of a lineage but not in older members.
Common ancestor