Explain Theory of Evolution through Natural Selection

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 solvings 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 supports the basic validity of the scheme of classification.