Q. Show the History of animal taxonomy?

The beginning of animal taxonomy was made by Aristotle (384-322 B.C.). He extensively studied about anatomy, embryology, habit and ecology. He was able to conclude that animals can be classified according to their way of living actions, habits and body parts. His major study includes: i) distinction of mandibulate from haustellate types, ii) winged from wingless forms among insects, iii) monitoring other animals like birds, fishes and whales. Orders like Coleoptera, Diptera and Psychae (now Lepidoptera) were created by him.

The first important work on both animal and plants was initiate4 by John Ray (1627-1705) Fig. 1,3 He followed Aristotle and divided animals those with blood and those apparently without blood. The former were further divided into those with gills and those with lungs. He also used other characteristics like the production of eggs or living young ones, the possession of broad hooves or narrow claws, the existence of two or more incisor teeth, and so on. Thus, he covered almost the entire animal kingdom. This system of classification was appreciated because, the system was logical, practical and easy to follow. He produced the first rudiments of our hierarchical classification and the first good definition of the species as a reproducing unit.

Then, in 18th century, the work of Linnaeus (Fig. 1.4) and his followers (Haartman, 1751, 1764, Kolreuter, 1761-66) helped systematic to advance further. Linnaeus-was first to introduce the hierarchical system both in animal and plant kingdom. He followed four categories (class, order, genus and species) for the animal world.

He also used the name Mammalla instead of Quadrupeda in 1758. He presented the first character-based classification which serves as basis for the arrangement of specimens in the collections and the binomial nomenclature for information storage and retrieval system for the great bulk of biological data. He was called "Father of 'taxonomy"

The criticism and improvements of the Linnean system continued but the first serious attempt to improve it was made by Lamarck. He divided the animal kingdom into three section on the basis of their mental capacities. His division of animals into four major types was-vertebrates, molluscs, arthropods and radiates.

Lamarck's taxonomy was mainly static in nature and his classification does not show its true value to the development of modern taxonomy. His most important support to the systematic was his preciseness in the diagnosis of various taxa. Many of his generic and other names are still in use. He displayed the groups of animals in form of a branching tree, which was the beginning of the , use of phylogeny in systematic.

Cuvier (1769-1832) was critical of Lamarck's evolutionary concept which thereafter remained in oblivion for half a century. Cuvier's outright criticisms of Lamarck greatly affected the progress of animal taxonomy during that period. And the following decades were known by emergence of three great ideas which influence a lot of progress in animal taxonomy. The first of these was 'Von Baer's Law' which was put forward by Von Baer. The, theory states that "The younger the embryo the more closely did it resemble other embryos of the same stage of development."

The second idea was an explanation of this rule by Ernst Hackel, which is known as Recapitulation theory or "Ontogeny repeats phylogeny"

The third theory of evolution through natural selection was put forward jointly by Darwin, and Wallace in 1859. This theory supported the idea of both Lamarck and Cuvier. Thus, this theory gave the greatest support to systematic zoology.

By the 19th century Darwin's ideas had been widely accepted. The Naturalists started searching for missing links between seemingly unconnected taxa and finally reconstructed the "primitive ancestors".'Phylogenetic trees were proposed by Hackel which also stimulated several empirical workers and large number of species were discovered and described.

Then came the modern taxonomy and with its development workers realised that the Linnean species based on one or two specimens are not as perfect as those which are based .on population studies. After these studies Mayer considered species as groups of interbreeding natural population. This idea of population taxonomy was useful in establishing "polytypic concept".

New terms like New Systematic and biosystematics were added. The faxonomists then realised the importance of other characters in sound classification. Then the scientists started searching for characters from field studies and various characteristics of living animals, namely behaviour, ecology, genetics, zoogeography, physiology, biochemistry. Thus, taxonomy got a new name 'biological taxonomy' in its true sense. The taxonomists came to know their dependence on new characteristics in solving species complexes and by about 1955 a state of 'taxonomic explosion' was reached.

Thus, present day taxonomic works include all available differences and similarities, phylogenetic adaptations, embryological patterns, biochemical variations, genetical similarity and behavioural characteristics etc. The general concordance of the data . from all such diverse source mutually support the basic validity of the scheme of classification.