Classification of Living Things Diversity of Life

What is classification? w Classification is the grouping of things according to similar characteristics What is the purpose of classifying organisms? w The science of classifying organisms is known as taxonomy

Why classify? w 1. to make known organisms easier to study– if you know what group they are in, you know characteristics. w 2. to help in the discovery of new organisms—scientists can put them into a known group Up to 6,000 new species are discovered every year (mostly plants, invertebrates, and microorganisms).

Why Classify? w 3. to help scientists from all around the world communicate with one another w The science of classifying organisms is known as taxonomy

Early classification systems w Aristotle (300 B.C.) was a famous philosopher, scientist, and mathematician. w grouped animals according to the way they moved

Binomial Nomenclature w Developed by Linnaeus : Swedish botanist (1730) w Placed organisms in groups based on observable features w Two-name system: Latin words w Each organism has a genus and a species name w First name (genus); second name (species)

What is a scientific name? w Combination of the genus and species name of an organism w Scientific names of organisms are always italicized or underlined: (Genus is capitalized; species name is lower-case) w Genus name can be abbreviated, species name cannot (H. sapiens for Homo Sapiens)

What classification system do scientists use today? w Based on the contributions of Linnaeus (shared characteristics) w Also takes into account the evolution of organisms (shared ancestors) w 8 Levels of Classification

Eight classification groups of living things w Domain w Kingdom w Phylum w Class w Order w Family w Genus w Species

w Each group is smaller than the one above it. w Each genus contains one or more species. w The species group contains only one organism. w The more classification levels two organisms share, the nclosely related they are. w Pg 19 (textbook)

Types of Taxonomic Keys w Taxonomic keys are used to help identify organisms w Dichotomous Key w Branching Diagram (Cladogram)

Dichotomous Key w A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish. w "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.

1. a. wings covered by an exoskeleton – go to step 2 b. wings freely observed – Go to step 3 2. a. body has a round shape ……….ladybug a red beetle with black spots b. body has an elongated shape ……….grasshopper a green insect that hops 3. a. wings point out from the side of the body ……….dragonfly an insect that is cm long and lives in marshes b. wings point to the posterior of the body ……….housefly a flying insect with red eyes and an annoying buzz

How Does A Branching Diagram (Cladogram) Work? w A branching Diagram groups organisms based on their common ancestors w Each characteristic on the branching diagram is shared by only the animals above it. w The characteristics found higher on the diagram evolved more recently than the characteristics below them.

Two organisms that are side by side on the branching diagram are more closely related than organisms that are farther apart.