different kinds of taxonomic characters and its function

SASNA.P.S

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