Taxonomy The science of classifying living organisms

History  During the 1700’s naturalists were bringing many examples of new species back to Britain  Scientists needed a way to keep all the organisms straight  Carolus Linnaeus came up with a classification system that we use today

History continued…  Linnaeus’ system originally had two kingdoms: –Plantae and Animalia  New kingdoms have been added as we learn new information  Now there are 6 kingdoms

The Seven Levels  Organisms are sorted into seven levels of classification: –Kingdom (the broadest, many type of organisms) –Phylum –Class –Order –Family –Genus –Species (the narrowest, one type of organism) King Philip came over for great spaghetti

The Seven Levels  Organisms are first put into kingdoms based on their similar characteristics –They are then further sorted through the seven levels  As you move DOWN the levels, the organisms in each level share more and more characteristics –The more levels two organisms share in common, the MORE related they are

The Seven Levels for a Mountain Lion

How do scientists classify organisms?  Scientists put organisms into groups based on SIMILAR CHARACTERISTICS –Always look for what characteristics organisms have in common  Scientists first began using physical evidence to classify organisms. –Now they also use fossil and DNA evidence

Classifying Organisms  Physical Evidence –Scientists examine: Skeletal Structure –Homogolous structures: Bones that are similar Common behaviors Similar appearance Habitats And more…

Classifying Organisms  Fossil Evidence –Scientists examine fossils to determine what organisms have common ancestors –Organisms with a recent common ancestor are more closely related than those with a very old common ancestor

Classifying Organisms  Genetic Evidence –Scientists have more recently started examining similarities in DNA and proteins –The more similar the DNA sequence, the more closely related are two organisms –Upon using genetic evidence, scientists found some previous classifications were incorrect

Classifying Organisms  DNA is the best evidence when classifying organisms  As scientists learn more about an organism, it’s classification may change

Scientific Names  Carolus Linnaeus came up with a system for assigning two name scientific names to an organism –His system is known as binomial nomenclature  Each organisms scientific name consists of it’s Genus name followed by it’s Species name

Scientific Names  When looking to identify commonly related organisms, use their first name –For example: Felis concolor (Pumas) are more closely related to Felis domesticous (house cats) than they are to Pinus concolor (white pine trees)

Scientific Names  Scientific names are used so that scientists from different countries can communicate easily about various types of organisms  Some organisms have more than one common name (ex. Mountain lion, puma, cougar) or different common names in different languages

Identifying Organisms  Scientists often need to identify organisms, so they know if it is a previously identified species –They use tools called a Dichotomous Key –Dichotomous Keys compare two traits in a step-by-step fashion to help one identify an organism

A Dichotomous Key 1. Has green colored body......go to 2 Has purple colored body..... go to 4 2. Has 4 legs.....go to 3 Has 8 legs Deerus octagis 3. Has a tail Deerus pestis Does not have a tail..... Deerus magnus 4. Has a pointy hump Deerus humpis Does not have a pointy hump.....go to 5 5. Has ears Deerus purplinis Does not have ears...…go to 6 Identify Organism D