1. Systematics is the study of the diversity and relationships among organisms, both living and extinct. It involves classifying organisms and determining their evolutionary relationships through tools like cladograms and phylogenetic trees. 2. Taxonomy is the practice of naming and grouping organisms, which is a key part of systematics. However, systematics also examines broader aspects of evolution through fields like genetics and molecular biology. 3. Systematics has many important applications, including aiding agriculture and forestry by identifying pests, enabling biological control of pests by introducing natural predators, and assisting in public health by identifying disease vectors.

1. Importance and
Applications
Systematics
HAFIZ M WASEEM

2. Contents:
 Definition of Systematics
 Cladograms and Phylogenetic
Trees
 Branches of Systematics
1. Numerical Systematics
2. Biochemical Systematics
3. Experimental Systematics
 Importance of Systematics
 Application of Systematics

3.  Systematics:
 The term systematics is derived from the Latinised Greek word and ‘systema’ means
‘together’. The systematics partly overlaps with taxonomy and originally used to des-
cribe the system of classification prescribed by early biologists. Linnaeus applied the
word “Systematics” in the system of classification in his famous book ‘Systema Natu-
rae’ published in 1735.
 Biological systematics is the study of the diversification of living forms both past and
present and the relationships among living things through time. Relationships are
visualized as evolutionary trees.
 According to Blackwelder and Boyden, “systematics is the entire field dealing with
the kinds of animals, their distinction, classification and evolution”.
 According to Christoffersen Systematics, is the theory, principles and practice of
identifying 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 classifi-
cation and nomenclature but inclines heavily on systematics for its concepts. So the
study of systematics includes a much broader aspect that includes not only
morphology and anatomy but also genetics, molecular biology, behavioral 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.
 Systematics uses taxonomy as a primary tool in understanding as nothing about an
organism's relationships with other living things can be understood without it first
being properly studied and described in sufficient detail to identify and classify it
correctly. Scientific classifications are aids in recording and reporting information to
other scientists and to laymen. The systematist is a scientist who specializes in

4. systematics must therefore, be able to use existing classification systems, or at least
know them well enough to skillfully justify not using them.
 Difference between Systematics and Taxonomy:
Taxonomy and systematics are two concepts related to the study of diversification of living
forms and the relationships of living things through time. The main difference between
taxonomy and systematics is that taxonomy is involved in the classification and naming of
organisms whereas systematics is involved in the determination of evolutionary relationships of
organisms. This means systematics ascertain the sharing of the common ancestry by different
organisms. In taxonomy, different organisms are scientifically named and grouped in different
taxonomic levels. Organisms are grouped based on their evolutionary relationships. Taxonomy
can be considered as a branch of systematics. Both taxonomy and systematics use
morphological, behavioral, genetics, and the biochemical observation.

5.  Cladograms:
A cladogram is a branching diagram which shows the evolutionary relationship among a group
of clades. A clade is a group of organisms, comprised of all the evolutionary descendants of a
common ancestor. A cladogram does not depict the amount of evolutionary change in the
group, nor does it indicate the evolutionary time or the genetic distance. Each branch of the
cladogram ends with a clade. It starts from a last common ancestor. Cladograms are usually
formed based on the morphological characters.
 Cladistics:
Cladistics refers to a biological classification system that involves the categorization of a
organisms based on shared traits. Organisms are typically grouped by how closely related
they are and thus cladistics can be used to trace ancestry back to shared common ancestors
and the evolution of various characteristics.
 Phylogenetic Trees:

6. A phylogenetic tree is a branching diagram which shows the inferred relationship between
various biological species. The distance of the branches in the phylogenetic tree represents the
amount of inferred evolutionary change. In order to generate a phylogenetic tree several
characteristics like external morphology, internal anatomy, biochemical pathways, behavior,
DNA and protein sequences, as well as the evidence of fossils have to be used. But,
phylogenetic trees are hypotheses and do not indicate the exact relationships. The data
obtained from DNA sequencing increases the reliability of the relationships in the tree. There
are two components of phylogenetic tree.
 Branch order shows the group relationships.
 Branch length shows the amount of evolution.
General Phylogenetic Tree

7. Phylogenetic Tree of Vertebrate
 Branches of Systematics:
1. Numerical systematics:
This type of systematics is based on bio-statistical method in identification and classification of
animals. This branch is called biometry. It aims to create a taxonomy using numeric algorithms
like cluster analysis rather than using subjective evaluation of their properties. The concept was
first developed by Robert R. Sokal and Peter H. A. Sneath in 1963 and later elaborated by the
same authors. They divided the field into phenetics in which classifications are formed based on
the patterns of overall similarities and cladistics in which classifications are based on the
branching patterns of the estimated evolutionary history of the taxa.
2. Biochemical Systematics:
This branch of systematics deals with classification of animals on the basis of biochemical
analysis of protoplasm.
3. Experimental Systematics:

8. 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.
 Importance of Systematics:
A. Theoretical biology:
Systematics has played some important role in the field of theoretical biology such as:
 It is responsible in making conceptual contribution like population thinking.
 It is responsible in solving the problems of multiplication of species. It illustrates the
structure of species and evolutionary processes.
 Mimicry and other evolutionary areas also have been a clearly understood through
taxonomy.
 It has also played important role in the development of behavioral science.
 Taxonomy is the key to the study of ecology, as no ecological survey can be undertaken
unless all the species of ecological importance are identified.
B. Applied Biology:
Systematics provides basic understanding about the components of biodiversity which is
necessary for effective decision making about conservation and sustainable use. The most
important uses are:
1. Agriculture and Forestry:
Presently we are faced with the acute problem of saving our crops and trees from the attack of
various kinds of pests. So, it is necessary to know the correct names of such pests; before their
proper control, and eradication. Taxonomists can give correct identification of pest species,
which is vital for its effective control. Similarly, many of the plant diseases are caused by certain

9. vectors. The correct identification of a particular vector is vital for bringing the vector under
control by killing its transmitters.
2. Biological Control:
Natural enemies of pests can be introduced for biological control of pests. The biological
control is much more economical than the chemical control. In 1940s a
parasite Archytusincertus was introduced from Uruguay and Argentina into the U.S.A. to
control armyworms. The systematics is presently greatly involved in designing and
implementing the biological control programmes of pests and diseases most effectively.
3. Public health:
Taxonomy plays an important role in public health program also. There are number of diseases,
which are spread by many Arthropods. So, our controlled measures should be planned to attack
the target species. As for example, All Anopheles maculipennis are not responsible for
transmitting malaria. This species consists of several sibling species, of which a few were

10. responsible for transmitting malaria. An expert taxonomist can identify this particular sibling
species. A correct identification ensures a maximum of effective control at minimum cost.
4. Quarantine:
Many new pests and diseases of plants, animals and human beings can spread from one
country to another through transportation. Respective Governments have established
quarantine laboratories at aerodromes, ports etc. to check such transmissions. Taxonomists
play a vital role here in prompt identification of these pests and diseases.
5. Wild life management:
Presently great attention is being paid to conserve and propagate wild life. The indiscriminate
killing and felling of trees have already resulted in great disturbance in the natural
environment. Taxonomists can help all environmental protectors by identifying the
economically and ecologically important wild life. The task is important for the preservation and
protection of our biodiversity.
6. Mineral prospecting:

11. The identification of fauna and flora in sedimentary rocks gives a clear picture of the sequence
of geological events, which helps in search for fuels and mineral deposits. The paleontologists
play a major role in the identification of such fossil specimens of the sedimentary rocks and
thus give us a clear picture of the correct sequence of geological events. Such works have been
great success in the industrialization in America.
7. National defense:
Information concerning disease vectors and parasites is an obvious application of
systematics to national defense. The use of biological means in the war is economical and
requires fewer efforts in their operation. During World War II, Japanese paper balloons carrying
paper balloons created havoc in the forest of north east America. Eventually a balloons was
recovered with sand contained a large number of shells of micro-organisms. The taxonomists of
America observed the shells of micro-organisms and confirmed that this type of sand represent
mainland island of Japan. Subsequent bombing of this beach area destroyed the balloon
launching site. Moreover, the identification of potential disease vectors is vital to the health of
both military and civilian populations all over the world.

12. 8. Environmental problem:
Taxonomists have played an important role in detecting some of the environmental
problems. Certain pesticides are entered in the food chain of ecosystem and biomagnifications
of pesticide takes place at certain tropic level. Here a taxonomist can play important role in
detecting such problem and can take effective measures to control it. Presently water pollution
is considered as a major environmental problem. Certain planktons are reliable indicator of the
degree of water pollution. The identification of such organism by taxonomists gives rapid
information for detecting pollution.

13. 9. Soil fertility:
Some organisms play important role in increasing the fertility of soil. So, it is necessary
to know such animals for their proper management in agriculture.
10. In Commerce:
Many animals and animal’s products are used commercially by human beings such as,
honey, silk, lace, dyes etc. Systematics play important role in increasing and improving the
qualities of these products by manipulating the useful species.
Systematists and taxonomists are presently employed by universities, research institute,
museum, central and state govt. agencies, industries, and zoos. A well trained taxonomist is
well qualified teacher to teach course of zoology or biology as he has a great background in
morphology, physiology, genetics and ecology.
 Applications of Systematics:
1. Studying the diversity of organisms and the differentiation between extinct and living
creatures. Biologists study the well-understood relationships by making many different
diagrams and "trees".

14. 2. Including the scientific names of organisms, species descriptions and overviews,
taxonomic orders and classifications of evolutionary and organism histories.
3. Explaining the biodiversity of the planet and its organisms. The systematic study is that
of conservation.
4. Manipulating and controlling the natural world. This includes the practice of 'biological
control', the intentional introduction of natural predators and disease.
 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.
2. 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.
3. 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.
4. 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 destroys different kinds of plants and animals for food
and other factors.
5. 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

15. 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 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.
6. 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 implement-
ing the biological control programmes of the pests and diseases most effectively.
7. 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 dengue fever and phlebotomies 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.
 References:
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