Taxonomy Bio 250

History of Taxonomy Aristotle Taxonomy – the branch of biology which names and groups organisms according to their characteristics Aristotle First person to put organisms in groups. - Grouped animals into land, air or water dwellers. At first, Aristotle’s system seemed adequate. When many new organisms were discovered, scientists began having problems. More groups were needed. Common names were different from place to place and caused confusion and did not describe the organism.

History of taxonomy cont. Linnaeus created a new system of grouping organisms. Based on their morphology (structure) Created 7 levels of classification Also created a two-part naming system called Binomial Nomenclature. Linnaeus

The 7 Levels of Classification Linnaeus devised seven levels of organization. Kingdom: the largest group of living things. Phylum: The largest group within a kingdom. Class: The largest group within a phylum. Order: The largest group within a class. Family: Largest group in an order. Genus: Largest group in a family. Species: Smallest group of living things.

Wait.. What were those again? No Looking! Kingdom Phylum Class Order Family Genus Species

Binomial Nomenclature The species name, also called the scientific name of an organism has two parts. The Genus name The species identifier The Genus name is capitalized, the species name is lower case and both are underlined or written in italics (typing only) Thus, our scientific name is written as such Homo sapiens or Homo sapiens. The full scientific name of a species will contain the the names of each classification group the organism is in. For Humans: Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Primata Family: Hominidae Genus: Homo species: sapiens

The Six Kindoms All life on Earth has been divided into six different kingdoms. Kingdom Archaebacteria Unicellular prokaryotes Cell membranes are different from other bacteria. Many live in harsh environments. Kingdom Eubacteria: These are the ones which affect you: tooth decay, food poisoning, disease, create food products like yogurt.

The Six Kingdoms cont. Kingdom Protista The catch-all Kingdom. If it’s eukaryotic and not a plant, animal or fungus, it’s in here. Mostly unicellular but do have some multicellular species. Some are plantlike and some are animalike.

The Six Kingdoms cont. Kingdom Fungi Multicellular, eukaryotic, heterotrophic Absorb nutrients – digest outside their body Includes mushrooms, puffballs, rusts, smuts, mildews, and molds

The Six Kingdoms cont. Kingdom Plantae Multicellular, eukaryotic, autotrophic Make their own food through photosynthesis Include mosses, ferns, conifers, and flowering plants

The Six Kingdoms cont. Kingdom Animalia Eukaryotic, heterotrophic, multicellular Can move around in their environment Insects, mammals, reptiles, amphibians, fish, birds, worms

The 3 Domain System Scientists have added another classification group ABOVE the level of Kingdom Molecular biology has shown that all organisms naturally fall into 3 large groups which are called Domains Domain Bacteria Contains the Kingdom Eubacteria Domain Archae Contains the Kingdom Archaebacteria Domain Eukarya Contains all Kingdoms with Eukaryotic cells Protista, Fungi, Plantae, Animalia

based upon specific traits. Taxonomy So how do we put all these organisms into groups? Today, scientists use either Systematics or Cladistics to put organisms into groups based upon specific traits. Systematics – Organizes the diversity of living things in the context of evolution. Creates a Phylogenetic Tree – A family tree which shows the evolutionary relationships thought to exist among groups of organisms. A phylogenetic tree represents a hypothesis. Scientists use morphology (structure), patterns of embryological development, similarity in DNA and proteins to construct phylogenetic trees.

Taxonomy cont. Cladistics – uses certain features of organisms called shared derived characters to establish evolutionary relationships. Derived Characters – are features that apparently evolved only within the group under consideration. Ex: If you’re studying birds, a derived character may be feathers. Scientists believe that if a group shares a character not shared with any other group, then they likely inherited it from a common ancestor. Cladogram – Ancestry diagram made by means of cladistics.