CLASSIFICATION SYSTEMS

LEARNING GOALS: By the end of class, I will be able to:  Explain how organisms are classified  Explain traditional and modern methods of classifying organism  Use and create a dichotomous key to identify and classify organisms

WARM UP – TAXONOMY How are all the items in a grocery store organized? What are common ways of organizing things? Why do we organize things?

INTRODUCTION TO CLASSIFICATION Taxonomy The science of naming, identifying and classifying organisms Biological Classification The organized grouping of organisms into categories based on:  physical and structural features  evolutionary relationships

CARL LINNAEUS Swedish scientist “father” of taxonomy classified organisms based on their physical similarities established the current binary naming system used to name species Binomial nomenclature Eg: Homo sapiens = humans Panthera leo = African lion

BINOMIAL NOMENCLATURE Each organism is assigned a 2 part scientific name using Latin words (sometimes Greek) Provides a common language for all scientists Organisms are named using their genus name followed by their species name  Homo sapiens Genus name is capitalized  Homo Species name is not capitalized  sapiens Both genus and species names are italicized  Homo sapiens

BINOMIAL NOMENCLATURE CONTINUED Ursus horribilis – grizzly bear Ursus americanus – North American black bear Ursus arctos – Alaskan brown bear Binomial Nomenclature can be used to determine how closely related to organisms are. Pg 334 Q 5 Also complete Pg 334 Q 6

LEVELS OF CLASSIFICATION 7 main levels or taxa (singular taxon) kingdom – group of phyla that share similar features phylum – group of classes that share similar features class – group of orders that share similar features order – group of families that share similar features family – group of genera that share similar features genus – group of species that share similar features species – group of organisms that can successfully reproduce Mnemonic: King Philip Came Over For Great Spaghetti Humans Kingdom – Animalia Phylum – Chordata Class – Mammalia Order – Primates Family – Hominidae Genus – Homo Species – Homo sapiens

SIX-KINGDOM CLASSIFICATION SYSTEM There are 6 kingdoms: Eubacteria  Prokaryotes; eg: bacteria Archaebacteria  Prokaryotes living in harsh habitats; eg: thermophiles Protista  Single or multicellular; some eukaryotes; eg. Algae Fungi  Multicellular, heterotrophs; eg: mushrooms, yeast Plantae Animalia See Page 329

THREE DOMAINS Today, many biologists call the broadest taxon a domain There are 3 domains:  Bacteria – prokaryotic cells  Archaea – prokaryotic cells  Eukarya – eukaryotic cells Prokaryotes: no true nucleus, mitochondria or chloroplasts Eukaryotes: more complex membrane-bound nucleus and organelles

MODERN CLASSIFICATION Linnaeus grouped species according to their morphology (structure and function) Biologists now use several types of evidence to help classify organisms including evolutionary relationships  Fossil records, historical geographical range, protein and DNA similarities, etc.  Based on the belief that organisms change over time Phylogeny is the history of evolution of a species or group of organisms  Phylogenetic trees (cladograms) are used to show these evolutionary relationships

PHYLOGENETIC TREES diagram representing evolutionary relationships between different species created using fossil records and similarities in genetic codes Clade is a group of species that include a single common ancestor. Clades vary in size. A large clade can include smaller clades.

DICHOTOMOUS KEYS A series of paired statements that lead to the identification of an organisms Used to help identify an unfamiliar organism Try Activity on pg 332 – Using a Classification Key Homework: pg 334 Q’s 1 and 2

DICHOTOMOUS KEYS – MORE PRACTICE Create a dichotomous key using the following footprints.