Chapter 1 Section 2 Classification

Why do we classify living things? Allows us to keep track of the 3 to 10 million different living things on Earth There have been many different ideas about how to classify living things Classification: The systematic grouping of organisms into categories on the basis of evolutionary relationships or physical appearance The Science of classifying is called “Taxonomy” People have been classifying for nearly 2,000 years

Classification Carolus Linnaeus Father of “Taxonomy” Developed systems for naming species and organizing them into groups Named over 4000 plants & animals Used appearance to group species Used binomial nomenclature * His system is still the one we use today

Scientific naming Binomial nomenclature is a system for naming organisms with two-word scientific name: The scientific name is made up of the genus & species name A genus, the first part of the scientific name, is a group of similar species. A species, the second part of the scientific name, is a group of organisms that have similar traits and are able to produce fertile offspring.

Scientific naming What is Binomial Nomenclature? “Binomial” = two-name “Nomenclature” = naming system Language: Latin Ex: common house cat – Felis domesticus Mountain lion, puma, cougar – Felis concolor Bobcat – Felis rufus The scientific name is made up of the genus & species name

Classification Organisms are now classified into one of three domains and then into one of six kingdoms.

Scientific naming Every living thing has its own unique scientific name based on the 7 levels of classification. These levels, from general to specific are: Kingdom Phylum Class Order Family Genus Species

Scientific names

Classification tools A dichotomous key is a series of descriptions arranged in pairs that lead the user to the identification of an unknown organism.

Classification tools A cladogram is a branched diagram that shows the relationships among organisms, including common ancestors.