Linnaean Hierarchy

Questions

(1) What is Hierarchy?.......1/2016TU,2018

(2)What are the obligatory categories used in Linnaean Hierarchy ?...2+2/2016TU

(3)Discuss the present status of Hierarchical Classification ....5/2016TU

(4) Discuss on Linnaean Hierarchy citing example of all taxa in man.....5/2018TU

            Hierarch=a series or succession of different ranks.So, in Systematics the term Hierarchy  is a method of arrangement of categories and taxa in an ascending order so that a higher category includes one or more lower category/categories .

     Linnaean Hierarchy & categories:

      Linnaeus, 1758 first time documented a  definite hierarchy for animals in 10th Edn.of Systema Naturae using only five categories , which are as follows:

(A Car Of Good Spice Varietas)

       (The descending sequence)

    Classis

       Order

          Genus

             Species

                Varietas

The category "varietas"used by Linnaeus was replaced by Sub-species .

               Seven Obligatory categories of a  taxonomic hierarchy:

  (King's PCO for Familie's  Good Security)

            (  The descrnding sequence )

   Kingdom

      Phylum

          Class

              Order

                  Family

                     Genus

                         Species

Linnaean Hierarchy and all taxa of Man 

   Kingdom .....Animalia

      Phylum.......Chordata

          Class........Mammalia

              Order.......Primates

                 Family......Hominidae

                      Genus.....Homo

                            Species....sapiens

  Hierarchical Classification and present status:

                    Advancement of science and technology along with the tedious search of  knowledge result in the increase of the number of known species of organisms . So, a given species requires more specific and precise position in the hierarchic classification .To arrange in a more proper & systemic way original seven obligatory categories are splitted and additional new categories inserted:

     (i) Cohort in between Class and Order,

    (ii) Tribe in between Family and Genus .

    Hence, the arrangement of these nine categories are as follows:

 Kingdom

    Phylum

       Class

           Cohort*

               Order

                   Family

                       Tribe*

                           Genus

                               Species

    Moreover, many more categories are added in the list . These categories are formed by adding prefixes :

(i)  as super- above the basic category ,

(ii) as sub- and infra- successively below the basic category .

e.g. basic category=Class

New categories = Super-Class

                                     (Class)

                                         Sub-Class

                                            Infra-Class

At present 33 categories are in use in the hierarchic classification , out of these 18 (asterisk-marked) are widely practiced . These 33 are as follows:

(First you write the 9 categories, then insert the new ones ...above & below ..Super Sub Inspector)

Kingdom

  Phylum

   Class

     Cohort

       Order

         Family

           Tribe

             Genus

               Species

(Now insert.......)

Kingdom*

  Subkingdom

     Infrakingdom

        Superphylum

          Phylum*

            Subphylum*

              Infraphylum

                Superclass*

                  Class*

                    Subclass*

                      Infraclass

                       Supercohort

                         Cohort*

                           Subcohort

                             Infracohort

                               Superorder*

                                 Order*

                                  Suborder*

                                   Infraorder

                                    Superfamily*(-oidea)

                                     Family*(-idea)

                                      Subfamily*(-inea)

                                       Infrafamily

                                        Supertribe

                                        Tribe*(-ini)

                                         Subtribe(ina)

                                          Infratribe

                                           Supergenus

                                            Genus*

                                             Subgenus*

                                              Superspecies

                                               Species*

                                                 Subspecies*

(No infragenus, infraspecies & Superkingdom )

 Important note*

(i)    A classifier should never leave any one of the seven Obligatory categories while stating the systematic position of an animal ; any violation of this will make the classification unsatisfactory . Therefore, these seven categories are mandatory or obligatory .

(ii) Use of rest categories are optional.

(iii) If a subsidiary level is used within any group , then it should be used for all the organisms of that group.

e.g. if a family is splitted into one or more subfamily , then all the genera should be kept in one or more subfamily.

Merits:

(i) More than one numerical schemes have been proposed to replace the Linnaean Hierarchy, but failed . The fact is that use of definite numerical values to taxa needs a vast knowledge of that taxa, which is not possible in reality.

(ii) In comparison to all other systems the Linnaean Hierarchy provides more and more  flexibility to the taxonomists while he /she is in practical field , by permitting splitting the seven obligatory categories to add new categories.

Therefore, Linnaean Hierarchy will be provisional for ever.