Classification

Classification A. Grouping objects, organisms, or information based on similarities B.Taxonomy - science of classifying organisms.

C.Why Study Taxonomy? Helps us organize living things to see relationships To find relatedness between organisms Ex. How related are two species of poisonous snakes?

Useful tool to quickly identify organisms. Ex. You see a snake or mushroom want to find its name and if it is poisonous. Ex. Identify a bird that you see on a nature hike.

taxonomists often discover new sources of lumber, medicine, and energy

D. Carolus Linnaeus (1707-1778) developed the binomial system of naming organisms. Avoids confusion by common or regional names Includes 7 categories

Binomial system - uses two words in which each organism is named by genus and species. Ex. Ursus maritimus (polar bear Felis domesticus (house cat) Homo sapiens (human) 1st word = Genus (Capital letter) 2nd word = species (lower case)

7 taxonomic categories or taxa.

Problems with traditional classification Often organisms were classified by the way they looked/anatomy, moved, or reproduced. Sometimes organisms that are very different evolve similar body structures.

Classification Now Organisms are grouped into categories representing lines of evolutionary descent, not just physical characteristics Cladograms - Tool that helps show evolutionary relationships among organisms

Cladistics groups organisms based on new characteristics that evolve over time. “evolutionary innovations” Look for derived characteristics - ones that appear in recent parts of lineage but not in older members.

similarities in DNA and RNA of organisms can be used in classification. Ex. Organisms that share more DNA sequences in common are more related

Changes in Classification We now use a 6 kingdom system of classification Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia DNA and RNA analysis has given rise to a new category: Domain Bacteria, Archaea, Eukarya