Taxonomy - importance, history and development and binomial nomenclature

Taxonomy - importance, history and development and binomial nomenclature. Definitions of Biotype, Sub-species, species, Genus, Family and Order.


Taxonomy - Importance, history and development and binomial nomenclature

Taxonomy is the process of identifying and classifying living organisms. Taxonomists study organisms and identify them based on their characteristics. These characteristics might be visible morphological characteristics or genetic differences.

Binominal nomenclature

The binomial naming system is the system used to name species. Each species is given a name that consists of two parts. The first part is the Genus to which the species belongs and the second part is the species name.
For example, Apis mellifera (the honey bee). The honey bee belongs to the Genus Apis and has a scientific name of Apis mellifera.
The binomial naming system was first uniformly used by Carl Linnaeus. Other names for (or types of) Binomial naming system include:

Biological classification
    Biological classification is the process by which scientists group living organisms. Organisms are classified based on how similar they are. Historically, similarity was determined by examining the physical characteristics of an organism but modern classification uses a variety of techniques including genetic analysis.

Organisms are classified according to a system of seven ranks:

Kingdom
   Phylum
      Class
         Order
             Family
                Genus
                    Species


For example, the honey bee (Apis mellifera) would be classified in the following way:

Kingdom = Animalia
    Phylum = Arthropoda
         Class = Insecta
              Order = Hymenoptera
                    Family = Apidae
                        Genus = Apis
                            Species = Apis mellifera

Species names are always written including the Genus in either full or abbreviated, for example, Apis mellifera or A. mellifera respectively.

BIOTYPE

A group of organisms having the same or nearly the same genotype, such as a particular strain of an insect species.

SUB-SPECIES

   A sub-division of a species, usually inhabiting a particular area: visibly different from other populations of the same species but still able to interbreed with them.
   A subspecies is further division of a species based on minor but constant differences in structure, appearance or biology. Individuals in different subspecies will be morphologically or genetically different from one another but still capable of interbreeding and producing viable offspring.

SPECIES

   The basic unit of living things, consisting of a group of individuals which all look more or less alike and which can all breed with each other to produce another generation of similar creatures.
   Species is one of the seven taxonomic ranks used to classify living organisms. A species can be defined as a group of organisms that can breed and produce fertile offspring.
   Historically speaking, species are described by taxonomists and what's called a Type specimen is catalogued and kept in a museum or other collection where scientists can access it. The Type specimen can be compared with other specimens to determine if they belong to the same species.
   In modern taxonomy scientists now consider a species to be a group of evolving organisms and have moved away from the idea of a historical Type specimen representing the form of a species.


GENUS

    A group of closely related species (plural: genera). The name of the genus is incorporated into the scientific names of all the member species: Pieris napi and Pieris rapae, for example, both belong to the genus Pieris
    Genus is one of the seven taxonomic ranks used to classify living organisms. Genus is positioned after Family and before Species.


1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species


FAMILY

A taxonomic subdivision of an order, suborder, or superfamily that contains a group of related subfamilies, tribes and genera. Family names always end in -idae.

ORDER

A subdivision of a class or subclass containing a group of related families.
Order is one of the seven taxonomic ranks used to classify living organisms. Order is positioned after Class and before Family.

1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species

There are 29 insect Orders although, like much of biological classification, this is still being discussed and changed by scientists.




CLASSIFICATION OF CLASS INSECTA UPTO ORDERS

Insect is a six legged arthropod. Taxonomist A.D. Imms proposed a classification of insect.

Phylum : Arthropoda (with several classes)
Class: Insecta (Hexapoda)

Characters of class Insecta

1. Body is divided into three regions
2. In head a pair of antenna and a pair of compound eyes are usually present.
3. Thorax is the centre of locomotion with, 3 pairs of five jointed legs and two pairs of wings.
4. Excretion is mainly through malpighian tubules.
5. Tracheal system of respiration well developed.
6. Brain is divided into protocerebrum, deutocerebrum and tritocerebrum.


The class Insecta has two subclasses viz., Apterygota and Pterygota



Apterygota

Pterygota

1.

Primarily wingless-evolved from wingless ancestors

Winged or secondarily wingless- evolved from winged ancestors. e.g. Flea, head louse, bed bug.

2.

Metamorphosis is totally absent or slight.

Present.

3.

Mandibular articulation monocondylic i.e., single

in

head

is

Dicondylic i.e., double.

4.

Pleural sulcus in thorax is absent.

Present.

5.

Pregenital abdominal appen- dages present.

Absent.




The subclass Apterygota has 4 orders namely
1. Thysanura - Silverfish (Thysan-fringed, Ura-tail)
2. Collembola- Springtail or snowflea (coll-glue; embol-peg)
3. Protura - Proturans or Telsontail (Pro-first, Ura-tail)
4. Diplura - Diplurans or Japygids (Di-two; Ura-tail)

The sub-class Pterygota has two division, namely Exopterygota and Endopterygota based on the wing development.



Character

Exopterygota

Endopterygota

1.

Wing development

External

Internal

2.

Type of metamorphosis

Incomplete(Hemimetabola) or gradual (Pau- rametabola)

Complete (Holome- tabola)

3.

Pupal stage

Absent

Present

4.

Immature stage

Naiad or Nymph

Larva

5.

No. of orders

16

9




The class Insecta has 29 orders (4 in Apterygota and 25 in Pterygota)

EXOPTERYGOTA  

Group I. Paleopteran orders (1,2)
1. Ephemeroptera - Mayflies 
2. Odonata - Dragonfly, Damselfly

Group II. Orthopteroid orders(3-11)
3.  Plecoptera - Stonefly 
4.  Grlloblatodia - Rock crawlers
5.  Orthoptera-Grasshopper, locust, cricket, mole cricket
6.  Phasmida-stick insect, leaf insect
7.  Dermaptera-Earwigs
8.  Embioptera-Webspinners/Embids
9.  Dictyoptera-cockroach, preying mantis
10. Isoptera - Termites
11. Zoraptera - Zorapterans

Group III. Hemipteroid orders(12-16)
12. Psocoptera - Book lice 
13. Mallophaga - Bird lice
14. Siphonculata - Head and body louse
15. Hemiptera - Bugs
16. Thysanoptera - Thrips


ENDOPTERYGOTA

Group IV. Panorpoid complex (1-9)
1. Neuroptera-Antilions, aphidlion, owl flies, mantispid flies.
2. Mecoptera - Scorpionflies. 
3. Lepidoptera - Butterflies and moths.
4. Trichoptera - Caddisfly.
5. Diptera - True fly.
6. Siphonaptera - Fleas.
7. Hymenoptera - Bees, wasps, ants.
8. Coleoptera - Beetles and weevils.
9. Strepsiptera - Stylopids.





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