Classification

1. Classification By Mr. Lacosse The first step in understanding and studying diversity is to describe and name each species. By using a scientific name, biologists can be sure that they are discussing the same organism. Common names can be confusing because they vary among languages and from place to place. For example, the names cougar, puma, panther, and mountain lion can all be used to indicate the same animal— FelisConcolor.

2. Assigning Scientific Names • In the eighteenth century, European scientists agreed to assign Latin or Greek names to each species. Early scientific names often used long phrases to describe species in great detail. • For example, the English translation of the scientific name of a tree might be “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.” • It was also difficult to standardize names because different scientists focused on different characteristics

3. Binomial Nomenclature • In the 1730s, Swedish botanist Carolus Linnaeus developed a two-word naming system called binomial nomenclature. • The scientific name usually is Latin. It is written in italics. The first word begins with a capital letter, and the second word is lowercased.

4. Binomial Nomenclature • The polar bear, for example, is called Ursusmaritimus. • The first part of the name—Ursus—is the genus to which the organism belongs. A genus is a group of similar species. The genus Ursuscontains five other species of bears, including Ursusarctos, the brown bear or grizzly bear.

5. Binomial Nomenclature • The second part of a scientific name—maritimusfor polar bears—is unique to each species and is often a description of the organism’s habitat or of an important trait. The Latin word maritimus refers to the sea: polar bears often live on pack ice that floats in the sea.

6. The scientific name of the Humans is Homo Sapiens. • The genus Homo. • The species sapiens

7. Classifying Species into Larger groups • In addition to naming organisms, biologists try to organize, or classify, living and fossil species into larger groups that have biological meaning. Biologists often refer to these groups as taxa (singular: taxon). • The science of naming and grouping organisms is called systematics.

8. Think About It!!

9. Linnaean Classification System • How did Linnaeus group species into larger taxa? • Over time, Linnaeus’s original classification system would expand to include seven hierarchical taxa: species, genus, family, order, class, phylum, and kingdom.

10. Linnaean Classification System • The first part of the name refers to the genus, or a group of similar species. • The second part of the name is unique to each species. • Just as a genus is a group of similar species, a family is a group of similar genera. • An order is a group of similar families. • A class is a group of similar orders. • A phylum is a group of similar classes. • A kingdom is a group of similar phyla.

12. Problems with the Traditional Classification • Linnaeus grouped organisms into larger taxa according to overall similarities and differences. But which similarities and differences are the most important? • Modern classification schemes look beyond overall similarities and differences and group organisms based on evolutionary relationships.