HOW ORGANISMS ARE CLASSIFIED

SEVERAL BASIC ASSUMPTIONS OR POSTULATES ARE MADE

1.     ORGANISMS SHOW DIFFERENT DEGREES OF SIMILARITIES
       AND DIFFERENCES AMONG INDIVIDUALS AND GROUPS

         
A.    ORGANISMS THAT ARE SIMILAR IN NEARLY ALL
                RESPECTS ARE A SPECIES
          B.    SPECIES THAT SHARE SOME OF THEIR
                CHARACTERISTICS MAKE UP A GENUS
          C.    GENERA THAT SHARE FEATURES ARE GROUPED
              
INTO FAMILIES
           D.    FAMILIES THAT SHARE FEATURES ARE GROUPED                  INTO ORDERS
          E.   ORDERS THAT SHOW SIMILARITIES ARE GROUPED                  INTO CLASSES
          F.    CLASSES THAT SHOW SIMILARITIES ARE GROUPED
 
               INTO DIVISIONS
                         G.    DIVISIONS THAT SHOW SIMILARITIES ARE
                GROUPED
INTO KINGDOMS

 KINGDOM

      DIVISION

           CLASS

                ORDER

                     FAMILY

                          GENUS

                               SPECIFIC EPITHET

 IN SCIENTIFIC NOMENCLATURE, EACH ORGANISM IS GIVEN TWO NAMES

 THE FIRST NAME IS THE GENUS

 THE SECOND NAME IS THE SPECIFIC EPITHET

 THE GENUS AND SPECIFIC EPITHET MAKE UP A SPECIES

 RULES OF WRITING A SCIENTIFIC NAME

     1.    BOTH NAMES ARE UNDERLINED, SEPARATELY OR WRITTEN            IN ITALICS
     2.    THE GENUS NAME IS CAPITALIZED
     3.    THE SPECIFIC EPITHET IS STARTED WITH A LOWER CASE
            LETTER
    
4.    THE SPECIES NAME IS FOLLOWED BY THE NAME OF THE
           PERSON WHO NAMED THE 0SPECIES

EX. Solanum tuberosum L.

HISTORY OF CLASSIFICATION

4th CENTURY -      ARISTOTLE
B.C.

                   THEOPHRASTUS

                   THEOPHRASTUS WROTE HISTORIA PLANTARUM WHICH                    DESCRIBED PARTS, USES AND HABITATS OF 
                  
PLANTS

                   DIVIDED PLANTS BASED ON LEAF SHAPE, AND
                   WHETHER THEY ARE TREES, SHRUBS OR
                   HERBS. CLASSIFIED 500 SPECIES OF PLANTS

1ST CENTURY    
   DIOSCORIDES
A.D.
    
              WROTE DE MATERIA MEDICA WHICH CLASSIFIED
                   PLANTS BASED ON THEIR MEDICINAL VALUE

                   PROBLEM: ONLY CLASSIFIED 600 PLANTS WITH
                   KNOWN MEDICAL VALUE.  PLANTS WITH NO KNOWN
                   MEDICAL USE WERE NOT DEALT WITH

                   USED FOR 1500 YEARS AND WERE THE BASIS OF
                  HERBALS

                   HERBALS LED TO THE DOCTRINE OF SIGNATURES

THE DOCTRINE OF SIGNATURES SAYS THAT IF A PLANT PART LOOKS
LIKE A BODY PART IT CAN BE USED TO TREAT AILMENTS OF
THAT BODY PART

EX. LIVERWORT (HEPATOPHYTE)

SOME PEOPLE THINK THE PLANTS LOOKED LIKE LIVER AND WERE USED TO TREAT LIVER AILMENTS.

EX. WALNUTS

SOME PEOPLE THINK THE NUTMEATS LOOK LIKE LITTLE BRAINS SO THEY ARE USED TO TREAT ILLNESS OF THE BRAIN

CAROLUS LINNAEUS (1707-1778)

GAVE PLANTS (AND OTHER ORGANISMS) A TWO PART SCIENTIFIC NAME

     BINOMIAL SYSTEM OF NOMENCLATURE

    
CLASSIFIED PLANTS BY THEIR REPRODUCTIVE PARTS

POST-LINNAEAN CLASSIFICATION

     NATURAL SYSTEMS DEVELOPED

     1.     NO EVOLUTIONARY BASIS
     2.     ASSUMED THAT LIVING ORGANISMS HAVE NOT CHANGED             SINCE THEIR CREATION AND WOULD NOT CHANGE IN THE
            FUTURE

MODERN CLASSIFICATION

     1.     BASED ON EVOLUTIONARY RELATIONSHIPS
            (PHYLOGENETICS)
     2.     NO AGREEMENT ON WHICH PHYLOGENETIC SYSTEM IS
               CORRECT
          a.     FIRST SYSTEM PROPOSED AROUND 1880.
          b.     RECOGNIZED 100,000 SPECIES
          c.     DEVELOPED BY ENGLER AND PRANTL

ENGLER AND PRANTLíS SYSTEM (1887 TO 1915)

    
1.     BASED ON THE FACT THAT FLOWERS LACKING PARTS ARE
               MORE PRIMATIVE THAN THOSE WITH MORE FLOWER PARTS
     2.     MONOCOTS WERE MORE PRIMATIVE THAN DICOTS

BESSEYS SYSTEM (1915)

    
1.     SAID THAT PLANTS WITH MORE FLOWER PARTS ARE MORE
               PRIMATIVE THAN THOSE WITH LESS

WHY ARE THERE SO MANY DIFFERENT PHYLOGENETIC SYSTEMS OF CLASSIFICATION?

DIFFERENT CHARACTERS ARE DETERMINED TO BE IMPORTANT BY DIFFERENT PEOPLE

EX. LEGUMES

1.   ONE TYPE OF FRUIT (ALL LEGUMES IN ONE FAMILY) - LUMPERS
2.   THREE TYPES OF FLOWERS (LEGUMES DIVIDED INTO THREE
     DIFFERENT SPECIES) - SPLITTERS

CLADISTICS - A SET OF CONCEPTS AND METHODS FOR DETERMINING CLADOGRAMS (BRANCHING PATTERNS OF EVOLUTION)

     CLADISTICS INVOLVES WORKING WITH CHARACTER STATES

     A CHARACTER STATE IS THE FORM OR VALUE OF A CHARACTER

          CHARACTER - FLOWER COLOR
          STATE - RED OR BLUE

                    -OR-

          CHARACTER - CHEMICAL TYPE FOR RED PIGMENT
          STATE - BETALIN-TYPE
                  ANTHOCYANIN-TYPE

YOU MUST DETERMINE WHAT STATE IS PRIMATIVE (ANCESTRAL) AND WHICH IS ADVANCED (DERIVED)

ASSUME ANTHOCYANIN-TYPE IS ANCESTRAL AND BETACYANIN IS DERIVED

     A PLANT WITH A DERIVED CHARACTER HAS A MORE RECENT
     COMMON ANCESTOR