161_systematics

161_systematics - 2-1 Laboratory 3Systematics and Taxonomy...

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Unformatted text preview: 2-1 Laboratory 3Systematics and Taxonomy by Dana Krempels and Julian Lee Recent estimates of our planet's biological diversity suggest that the species number between 5 and 50 million, or even more. To effectively study the myriad organisms that inhabit the biosphere, we attempt to classify organisms into groups that reflect evolutionary relationships. The science of describing, classifying and naming organisms is known as taxonomy. The science of studying their diversity and evolutionary relationships is known as biosystematics, orsimplysystematics. I. TaxonomyStrictly speaking, taxonomyis the sorting of living organisms into various taxonomic groups, ortaxa (sing. = taxon). Since most systematists are concerned not only with the ability to sort and identify organisms, but also with determining their evolutionary relationships, taxonomy is used as a tool within systematics . Biological nomenclatureis the application of names to organisms recognized to be part of a particular taxon. From most inclusive to least inclusive, the major taxonomic ranksare as follows: DOMAIN (e.g., Eukarya)KINGDOM(e. g., Animalia) PHYLUM (e. g., Chordata) CLASS(e. g., Mammalia) ORDER(e. g., Primates) FAMILY(e. g., Pongidae) GENUS(e. g., Homo) SPECIES (e. g., Homo sapiens) Each Domaincontains several Kingdoms. The Kingdoms are made up of related phyla. Phyla, in turn, are composed of related classesof organisms, classes of related orders, orders of related families, families of related genera(singular: genus) and genera of related species. Within each of the major taxonomic ranks there may be larger and smaller taxa such as subkingdom, superphylum, subphylum, subclass, etc. Living organisms were once classified into five Kingdoms (Monera, Protista, Fungi, Animalia and Plantae). More recent data indicate that Monera and Protista included organisms descended from more than a single common ancestor. In modern systematics, this is not acceptable, and so Monera and Protista were dismantled and their members assigned to taxa that more accurately reflect evolutionary relationships. Every described, named organism is nested into a complete organizational hierarchy, from species through its domain, as shown above for our own species, Homo sapiens. Note that the scientific name of an organism (its genus and species) is alwayswritten with the genus capitalized and the specific epithetin lower case letters. Because the words are Latinized, they should be italicized(as is any text written in a language other than that of the main body of the writing, n' c'est pas)?. This standard form was devised by Swedish botanist Carl Linne (who Latinized his own name to Carolus Linnaeus, and who is best known by his last name, Linnaeus) in his seminal work, Systema naturae(1735). 2-2 A. The Aspects of a TaxonA taxon is generally considered to have three aspects: 1. The taxon's name.For example, the name of the taxon containing all domestic dogs is Canis familiaris.The order to which all dogs belong (along with a host of other...
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161_systematics - 2-1 Laboratory 3Systematics and Taxonomy...

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