In this article we will discuss about Systematics:- 1. Meaning of Systematics 2. Branches of Systematics 3. Applications in Biology.
Meaning of Systematics:
The term systematics is derived from the Latinised Greek word and ‘systema’ means ‘together’. The systematics partly overlap with taxonomy and originally used to describe the system of classification prescribed by early biologists. Linnaeus applied the word “Systematics” in the system of classification in his famous book ‘Systema Naturae’ published in 1735.
Blackwelder and Boyden (1952) gave a definition that “systematics is the entire field dealing with the kinds of animals, their distinction, classification and evolution”. C. G. Simpson (1961) considers that “Systematics is the scientific study of the kinds and diversity of organisms and of any and all relationships among them”.
The simpler definition by Ernst Mayr (1969), and Mayr and Ashlock (1991) is “Systematics is the science of the diversity of organisms”. Christoffersen (1995) has defined systematics as “the theory, principles and practice of identifying (discovering) systems, i.e., of ordering the diversity of organisms (parts) into more general systems of taxa according to the most general causal processes”.
The systematics includes both taxonomy and evolution. Taxonomy includes classification and nomenclature but inclines heavily on systematics for its concepts. So study of systematics includes a much broader aspect that includes not only morphology and anatomy but also genetics, molecular biology, behavioural aspects and evolutionary biology.
The recent approach to the science of biology has added a new dimension to the science of classification and the new systematics has emerged as a synthesis of progress in all the major disciplines of Biology.
Branches of Systematics:
The new systematics may be divided into following branches:
1. Numerical systematics:
This type of systematics is based on bio-statistical method in identification and classification of animals. This branch is called biometry.
2. Biochemical systematics:
This branch of systematics deals with classification of animals on the basis of biochemical analysis of protoplasm.
3. Experimental systematics:
This branch of systematics deals with identification of various evolutionary units within a species and their role in the process of evolution. Here mutation is considered as evolutionary unit.
Application of Systematics in Biology:
1. Systematics is the study of diversity of organisms including past and present and relationships among living things. Relationships are established by making cladograms, phylogenetic trees and phylogenies. The phylogeny is the evolutionary history of an animal or plant, for a taxonomic group.
Phylogenies include two parts—the first part shows the group relationships and the second part indicates the amount of evolution. Phylogenetic trees of species and higher taxa are established by morphological, physiological and molecular characteristics, and the distribution of animals and their ancestors are related to geography. In this way the systematics is used to understand the evolutionary history of organisms.
2. The field of systematics provides scientific names of the organisms, description of the species, ordering the organisms into higher taxa, classification of the organisms and evolutionary histories.
3. Systematics is also important in implementing the conservation issues because it attempts to explain the biodiversity which is related to different kinds of species and could be used in preservation and protect the endangered animals and plants.
The loss of biodiversity is related to the extreme harmful of the existence of mankind. The unchecked human population destroy different kinds of plants and animals for food and other factors.
4. The destruction or suppression of harmful pests or animals by the introduction and increase of their natural enemies is called biological control.
The natural enemies of pests are often introduced for biological control for the advantage of agriculture and forestry. The natural enemies include insectivorous spiders, centipedes, some insects, frogs and birds which are much more economical than the chemical control because they have no injurious side effects.
The predaceous insects play a vital role in the natural control of injurious insects. The adult and larval stages of predatory insects of lady bird beetles (Coccinellidae) are economically very important and are responsible for the destruction of the colonies of plant lice, scale insects, mealy bugs and white flies which are found as serious pests in various parts of the world.
Some chrysopids are also predatory enemies of mealy bugs and plant lice. An egg parasite, Trichogramma sp. is utilized in India for the control of sugar cane borers and boll worms of cotton.
In all cases the proper identification of parasites and their hosts are necessary for the control of the pests. The systematists are involved in implementing the biological control programmes of the pests and diseases most effectively.
5. There are a lot of insects which act as vectors of various human diseases. For example, some species of Anopheles sp. are the vector of malaria diseases, Aedes aegypti spreads the virus of dengu fever and phlebotomus argentipes spreads the pathogens of kala-azar fever.
So taxonomists play a vital role in identification of the species of vectors, and control strategy programmes of the vectors should be planned in such a way that the target species is attacked.