113 cytotaxonomy the characterization and

1.1.3 Cytotaxonomy
The characterization and identification of a cell’s complete
chromosome set is referred to as karyotyping . It is the first stage in the

7
process of using chromosomes in taxonomy.
Karyotypes within interbreeding populations of a species are usually
constant. Between species there may be variation in chromosome number
and size. Final stages of chromosomal aberrations such as inversions and
translocations can give clues regarding intermediary stages.
1.1.4 Chemotaxonomy
Chemotaxonomy refers to the use of information about small molecules
produced by the action of enzymes. Protein fractions in
electrophoretic techniques, identification of amino acids in chromatography,
prevalence of isoenzymes in tissue materials are all tools
employed in chemotaxonomy. The occurrence of specific pheromones, colour
pigments, toxins also help as keys in taxonomy.
1.1.5 Palaeotaxonomy
This method depends on identification and dating of fossils. Availabil-
ity of a good complete fossil provides better chance for
identification. 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 to
assign a fossil to a genus or other higher level, fixing the species is not always
possible.
1.1.6 Nomenclature methods
Nomenclature forms the basis by which scientists can name and cross
refer to organisms. It is an integral part of taxonomy. In fact, modern tax-
onomy started in 1753 with the publication of first part of Systema by Linnaeus .
According to Linnaeus a Species is specified by the combination of both its
specific and generic names. Since it requires two names, it is referred to as
the 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. These
commissions authorize the usage of scientific names in biology. Naming of
animals 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 by
occasional science congresses.

8