different kinds of taxonomic characters and its function
TRANSCRIPT
THE KINDS OF TAXONOMICAL CHARACTERS FALL UNDER FIVE HEADINGS...
MORPHOLOGICAL CHARACTERS
PHYSIOLOGICAL CHARACTERS
ECOLOGICAL CHARACTERS
ETHOLOGICAL CHARACTERS
GEOGRAPHICAL CHARACTERS
EXTERNAL FEATURES PROVIDE PRIMARY AND EVIDENT SOURCE FOR IDENTIFYING THE TAXONOMIC CHARACTERS
THEY RANGE FROM SUPERFICIAL FEATURES ASPLUMAGE AND PELAGE CHARACTERS OF BIRDS AND MAMMALS,SCALES IN REPTILES AND FISH,SCLERITES AND SUTURES OF ARTHROPOD BODY
ANIMAL WITH EXTERNAL SKELETON(ARTHROPOD &MOLLUSCS)
IN GENERAL THE GENITALIC DIFFERENCE MUST BE EVALUATED JUST LIKE OTHER CHARACTERS;BECAUSE GENITALIC STRUCTURES APPEAR TO BE AMONG THE FIRST TO CHANGE IN THE COURSE OF SPECIATION.
GENITALIC FEATURES HAVE BEEN FOUND TO VARY IN THE SAME MANNER AS OTHER CHARACTERS(JORDAN,1905)
GENITALIC DIFFERENCES WILL LEAD TO RI (reproductive isolation-leon dufour)
DUFOUR PROPOSED A LOCK AND KEY HYPOTHESIS –STRUCTURAL DIFFERENCE IN GENITALIA PREVENT SPECIES FROM HYBRIDISING
ANATOMY ALSO PROVIDE ABUDANT SOURCE FOR TAXONOMIC CHARACTERS IN PRACTICALLY ALL GROUPOF HIGHER ANIMALS
Eg: INTERNAL SKELETON(The skull) ARE ROUTINELY PRESERVED FOR IDENTIFICATION
IT OFFER TAXONOMIC CHARACTERS OF GREAT PHYLOGENETIC SIGNIFICANCE...
CLEAVAGE PATTERN
BLASTULATION
GASTRULATION
Eg:The total holoblastic cleavage of springtail emphazize a wide gap which seperate this group from apterygota and pterygota
IT IS ALSO A DETERMINATION FACTOR FOR TAXONOMIST TO CHARACTERISE AN ORGANISM,THE SIMPLEST CYTOLOGICAL CHARACTER IS CHROMOSOMAL NUMBER
CHROMOSOMAL NUMBER HAVE BEEN RECORDED FOR THOUSANDS OF ANIMALS ,SUCH STUDIES HAVE USED AS A EVIDENCE OF PHYLOGENETIC RELATION SHIP
CHROMOSOME MORPHOLOGY (CHROMOSOMAL VARIATION)
Eg:DROSOPHILA
A.METABOLIC FACTORS 1.ENZYMATIC ACTIVITY(ANABOLIC AND CATABOLIC
REACTIONS)
2.CELL CHEMISTRY(GRAM –VE &GRAM +VE )
METABOLIC REQUIREMENTS ARE OF GREAT IMPORTANCE ;WHETHER A BACTERIA IS AEROBIC OR ANAEROBIC,AND HOW THEIR CULTURAL GROWTH PATTERN AND COLORATION IN MEDIA
IT IS HELPFUL IN THE SEPERATION OF CLOSELY RELATED SPECIES
SEROLOGY IS CONCERNED WITH THE NATURE AND INTERACTION OF ANTIGENS AND ANTIBODIES
ANTIGENS ARE THE SUBSTANCES CAPABLE FOR INDUCING THE FORMATION OF ANTIBODIES WHEN INTRODUCED IN TOTHE BLOOD STREAM OF ANIMALS
ANTIBODIES PRODUCED IN RESPONSE TO THE INTRODUCTION OF FOREIGN ANTIGEN
BOVDEN(1943) HE LISTED THE BASIC PREMISES OF SEROLOGY AS FOLLOWS:
1. THE ANTIGENIC COMPOSITION IS AN IMPORTANT PART OF THEIR ESSENTIAL NATURES MAY BE CONSIDERED IN NATURAL SYSTEM OF CLASSIFICATION
2.PROTEIN ANTIGENS ARE CONSERVATIVE HEREDITARY TRAIT
3.GOOD PRECIPITIN TECHNIQUE ARE WELL ADAPTED TO REVEAL THE RELATIVE DEGREE OF BIOCHEMICAL SIMILARITY OF PRIOTEIN ANTIGENS
THIS WAS AN ANOTHER PHYSIOLOGICAL CHARACTER WHICH HAS PROVED USEFUL IN TAXONOMY INVOLVE BODY SECRETIONS WHICH FORM CONSISTENT PATTERNS
Eg:THE WAXY SECRETIONS OF SCALE INSECTAND MEALY BUG
FROM THIS WAX PATTERNS WE CAN UNDERSTAND
MORPHOLOGY
THE NUMBERS
SIZE
ARRANGEMENT OF WAX GLANDS
EARLY TAXONOMIST KNEW THAT THERE IS MUCH STERILITY IN BETWEEN MEMBERS OF DIFFERENT SPECIES SO ITS IS CONSIDERED AS A CRITERIA FOR IDENTIFYING TAXONOMIC FEATUTRES
Eg: 1. IN SOME CASES DISTINCT SPECIES MAY COMPLETELY INTERFERTILE
2.THERE MAY BE A CONSIDERABLE AMOUNT OF STERILITY EVEN BETWEEN SUBSPECIES OF A SINGLE SPECIES
A.HABITAT EACH SPECIES HAVE ITS OWN RANGE OF TOLERANCE
OF HABITAT
NO TWO SPECIES WITH IDENTICAL ECOLOGICALREQUIREMENT CAN COEXIST IN THE SAMEPLACE(GAUSE’S LAW)
EACH GENERA OCCUPIES A SEPERATE ADAPTIVE ZONE (SIMPSON)
Eg: GALAPAGOSE FINCHES
• HOST discrimination
• THE METHOD OFUSING DIFFERENCE IN PARASITE OR COMMENSAL TO DISTINGUISH BETWEEN EXCEEDINGLY SIMILAR SIBLING SPECIES IS VERY USEFUL
FOOD IS A IMPORTANT TAXONOMIC CHARACTERS IN MONOPHAGOUS OR PARASITIC ORGANISM
c.seasonal variation
• SEASONAL VARIATION ARE ALSO A KIND OF TAXONOMIC FEATURES.FROM THIS WE CAN ALSO IDENTIFY THE ORGANISMS
• Eg: stick insect,butterfly,polar bear
Eg; CASE OF BARK BEETLE
Eg: TAPE WORM (Hymnolepis nana) in man & H.fraterna in rodents
Eg: ASCAIS in humans and pig are different
IT IS THE REACTION OF THE HOST TOWARDS A SPECIFIC PARASITE.IT HAS BEEN USED FOR TAXONOMIC PURPOSES
Eg: GALLS PRODUCED IN RESPONSE TO ATTACK BY VARIOUS GALL WASPS (CYNIPIDIAE) GALL FILES
A.COURTSHIP AND OTHER ISOLATING
MECHANISMS
DIFFERENCE IN MATING HABITS ARE ESPECIALLY IMPORTANT BEHAVIOR CHARACTERS,SINCE THEY ARE MORE LIKELY TO RESULT IN REPRODUCTIVE ISOLATION AND CONSEQUENT SPECIATION
Eg : slugs
1.THE NATURE OF WEBBING CONSTRUCTED
BY VARIOUS SPIDERS
2.THE USE OF EXTRANEOUS MATERIAL IN THE CONSTRUCTION OF NEST OR LARVAL OR PUPAL CASES
3.SOME BEHAVIOURAL PATTERN ARE MORE CONSERVATIVE
.DRINKING HABIT OF PIGEON AND SAND GROUSE
USE OF MUD IN NEST BUILDING
A. GENERAL BIOGEOGRAPHICAL
PATTERN
BIOGEOGRAPHERS HAVE DIVIDED THE WORLD IN TO REALMS,REGIONS,PROVINCES,SUB PROVINCES Etc.. BASED UPON GENERALISED COMPARISON OF FAUNA AND FLORA
A TAXONOMIST SHOULD HAVE AN UNDERSTANDING OF THE GEOLOGICAL HISTORY OF THE REGIONS IN WHICH SUCH AS A BIOTAS CENTER,AND THE KNOWLEDGE OF THE PAST RELATIONSHIPS OF THE FAUNA AND FLORA
SYMPATRIC--ONE PARTICULAR SPECIES IS FORMED IN A SAME POPULATION(REPRODUCTIVE ISOLATION--EVOLUTIONARY PROCESS---NEW SPECIES)
ALLOPATRIC--ONE PARTICULAR SPECIES IS EVOVED DUE TO GEOGRAPHICAL SEPERATION(THIS DISTRIBUTIONAL PATTERN IN CLOSSELY RELATED FORMS IS NOW GENERALLY CONSIDEREA TO BE INDICATIVE OF A POLYTYPIC SPECIES CONSISTING OF SEVERAL SUBSPECIES)
THEY HAVE DIAGONOSTIC ASPECTS AS INDICATORS OF DIFFERENCE
THEY FUNCTION AS INDICATORS OF RELATION SHIP
KEY CHARACTERS –EASILY PRODUCED,VARIABILITY,REPRESENTING MATERIAL
HELP IN CLASSIFICATION OF ORGANISMS