Numerical Taxonomy – Class 11 | Chapter – 3 | Short Notes Series PDF
Numerical Taxonomy is the technique of classifying organisms using numerical methods. This method firmly clarifies as well as displays the degree of link among the species. Organisms are classified into taxa according to their similarities and differences. Numerical Taxonomy is at present a very essential part of current systematics. Numerical Taxonomy is also known as Taximetrics; however, presently it is more commonly referred to as Phenetics.
It is the Numerical evaluation of the similarities or affinities of taxonomic units, which are typically classified into taxa based on their affinities.
It uses statistical methods to assess resemblances and differences, as well as primitiveness and advancement, based on a huge number of features gathered from several areas of biology.
In the 1950s, phenetics, often known as numerical taxonomy, was introduced.
Phenetics is a branch of biology that aims to classify species into higher taxa based on overall resemblance, usually in appearance or other visible qualities, rather than phylogeny or evolutionary relationships. It was developed by Adanson which is based on all observable characteristics and each character is given equal importance. Hundreds of characters can be considered at the same time. Numbers and codes are assigned to all characters and data and then processed using a computer or statistical method.
Sneath and Sokal (1973) gave various examples of numerical taxonomy being used in several angiosperm taxa, including Apocynum, Crotalaria, Cucurbita, Chenopodium, Oenothera, Salix, Zinnia, Barley cultivars, Maize cultivars, Wheat cultivars, and so on.
Merits of Numerical Taxonomy
The data of conventional taxonomy is improved by Numerical Taxonomy as it uses more numbers and better-described characters.
The data are collected from a variety of sources, such as morphology, chemistry, physiology, etc.
As Numerical methods are more sensitive for delimiting taxa, the data obtained can be efficiently used in the construction of better classification systems and keys.
Numerical Taxonomy has in fact suggested several fundamental changes in the conventional classification systems.
The number of existing biological concepts has been reinterpreted in the light of Numerical Taxonomy.
Numerical Taxonomy allows more taxonomic work to be done by the workers that ate not much skilled.
Demerits of Numerical Taxonomy
The Numerical methods come along with phenetic classifications and not phylogenetic classifications.
The determined limits held by these techniques may not be accepted by the proponents of the “biological” species concept.
In this method, the greatest disadvantage is character selection. If characters selected for comparison are not enough, the statistical methods may not give the expected solution.
Different taxometric procedures may conclude in different results, according to Steam. A crucial difficulty is to choose a process for the requirement and the number of traits necessary in order to get expected results from these mechanical aids.
It is also very important to ascertain whether a large number of traits would really conclude with much-expected results than those using a smaller number of traits.