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1.1.3 CytotaxonomyThe characterization and identification of a cell’s completechromosomeset is referred to as karyotyping. It is the first stage in the
7process of using chromosomes in taxonomy.Karyotypes within interbreeding populations of a species are usuallyconstant. Between species there may be variation in chromosome numberand size. Final stages of chromosomal aberrations such as inversions andtranslocations can give clues regarding intermediary stages.1.1.4 ChemotaxonomyChemotaxonomy refers to the use of information about small moleculesproduced by the action of enzymes. Protein fractions inelectrophoretic techniques, identification of amino acids in chromatography,prevalence of isoenzymes in tissue materials are all toolsemployed in chemotaxonomy. The occurrence of specific pheromones, colourpigments, toxins also help as keys in taxonomy.1.1.5 PalaeotaxonomyThis method depends on identification and dating of fossils. Availabil-ity of a good complete fossil provides better chance foridentification. In several fossils, their sections taken through laborious pro-cesses have provided the identification features.The fossils are normally studied along with other accompanying fos-sils, its geographic location and other factors. Even though it is possible toassign a fossil to a genus or other higher level, fixing the species is not alwayspossible.1.1.6 Nomenclature methodsNomenclature forms the basis by which scientists can name and crossrefer to organisms. It is an integral part of taxonomy. In fact, modern tax-onomy started in 1753 with the publication of first part of Systemaby Linnaeus.According to Linnaeus a Species is specified by the combination of both itsspecific and generic names. Since it requires two names, it is referred to asthe binomial system. This system is now firmly established in Biology.In modern times International Commissions are responsible for nam-ing each major group of organisms. There are several such commissions. Thesecommissions authorize the usage of scientific names in biology. Naming ofanimals is monitored by International Code of Zoological Nomenclature(ICZN) (International Commission of Zoological Nomenclature, 1985).The rules are set out in the ‘codes’. The codes are modified byoccasional science congresses.