Taxonomy The science of classifying living organisms History

Taxonomy The science of classifying living organisms

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

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

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

The Seven Levels v Organisms are first put into kingdoms based on their similar characteristics – They are then further sorted through the seven levels v 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? v Scientists put organisms into groups based on SIMILAR CHARACTERISTICS – Always look for what characteristics organisms have in common v Scientists first began using physical evidence to classify organisms. – Now they also use fossil and DNA evidence

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

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

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

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

Identifying Organisms v 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 stepby-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