18-1 Finding Order in Diversity Photo credit: ©Gary Randall/Visuals Unlimited

18-1 Finding Order in Diversity Natural selection and other processes have led to a staggering diversity of organisms. Biologists have identified and named about ______________________. They estimate that 2–100 million additional species have yet to be discovered.

Why Classify? What’s the point? To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner. In the discipline of taxonomy,

Assigning Scientific Names Common names of organisms vary, so scientists assign one name for each species. Scientific names are always: Homo Sapiens Toxicodendron radicans

Assigning Scientific Names Carolus Linnaeus developed a naming system called: In binomial nomenclature, The scientific name is italicized. Carcharodon carcharias Phoenicopterus roseus

Linnaeus’s System of Classification Linnaeus not only named species, he also grouped them into seven levels of categories. From largest to smallest

Linnaeus’s System of Classification Each level is called a ________, or taxonomic category. Species and genus are the two smallest categories. Grizzly bear Black bear Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

Linnaeus’s System of Classification Genera that share many characteristics are grouped in a larger category, the ________. Grizzly bear Black bear Giant panda Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

Linnaeus’s System of Classification An _________ is a broad category composed of similar families. Grizzly bear Black bear Giant panda Red fox Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

Linnaeus’s System of Classification The next larger category, the _______, is composed of similar orders. Grizzly bear Black bear Giant panda Red fox Abert squirrel Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level. Class Mammalia

Linnaeus’s System of Classification Several different classes make up a ____________. Grizzly bear Black bear Giant panda Red fox Abert squirrel Coral snake PHYLUM Chordata Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level. Copyright Pearson Prentice Hall

Linnaeus’s System of Classification The ________is the largest and most inclusive of Linnaeus's taxonomic categories. Grizzly bear Black bear Giant panda Red fox Abert squirrel Coral snake Sea star KINGDOM Animalia Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

Grizzly bear Black bear Giant panda Red fox Sea star Abert squirrel Coral snake Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.