Presentation on theme: "Taxonomy The classification of living things…. There may be over 100 million different living things on Earth. Less than 2 million have been classified."— Presentation transcript:
There may be over 100 million different living things on Earth. Less than 2 million have been classified at this time. The science of naming and classifying living things is called taxonomy.
Naming a species: A species can be scientifically named using binomial nomenclature (two name). This means that the organism is named using its genus and species name. The entire scientific name is always written in italics. The genus name is always capitalized Homo sapiens
The Hierarchy of Classification Carolus Linnaeus (1707- 1778) used binomial nomenclature to name living things which he placed in groups according to their characteristics. He proposed a hierarchy which had levels (taxa) that included a very broad range of organisms, like animals and plants, and more specific groups like genus and species.
Levels of Classification Kingdom Phylum Class Order Family Genus species
Classification of Humans Kingdom Animalia Phylum Chordata Class Mammalia Order Primates Family Hominidae Genus Homo species sapiens
Evolutionary Classification Classification has changed over time from grouping based on physical characteristics to grouping based on evolutionary history and genetics Phylogeny – evolutionary relationships among organisms Derived characters – characteristics that appear in organisms that were not present in “older” organisms
Cladogram – shows evolutionary relationships between organisms
Molecular Clocks DNA (and mitochondrial DNA) is always changing and mutations happen all the time Scientists can tell how closely related organisms are based on differences in DNA and the subsequent amino acid sequences in proteins. Modern tool to help scientists classify organisms
How are all things classified? The “Kingdoms” have changed over time... 1700s – Plantae, Animalia 1800s – Protista, Plantae, Animalia 1950s – Monera, Protista, Fungi, Plantae, Animalia 1990s – Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia Why???