Insect Taxonomy—Basics to Barcoding 99
heterozygous individuals. However, the limited
number of proteins and isozymes as markers and
requirement of different protocols for each en-
zyme/protein limit their utility. Unlike morpho-
logical and protein-based markers, several DNA
based markers are available to elicit the differ-
ences between individuals and populations, or
they can be developed for each specific purpose.
Although a large number of samples can be ana-
lyzed quickly, a number of other factors such as
cost, speed, and requirements of technical skills
are the major concern. DNA-based markers can
generate large amount of high quality data com-
pared to several biochemical marker systems, but
degree of polymorphism detected and the sta-
tistical dependability of the results vary among
marker systems.
Integrative Taxonomy
Will et al. ( 2005 ) a slight critique of DNA barcod-
ing, used the term integrative taxonomy to mean
a taxonomic process that was inclusive of all
available data sources and not just mtDNA COI
barcode data. Dayrat ( 2005 ) defined “Integrative
taxonomy” as the science that aims to delimit the
units of life’s diversity from multiple and com-
plementary perspectives. Thus, any study linking
different kinds of data by mapping morphologi-
cal diversity on to a molecular phylogeny is inte-
grative (Yeates et al. 2011 ).
Integrative taxonomy gives priority to morpho-
logical characters because of their greater com-
plexity and presumed multigenic origin, which
are believed to constitute a more secure basis for
separating species than small fragments of DNA
sequence. The limitation of molecular system-
atics—being an essentially cladistic approach,
is that it assumes that classification must corre-
spond to phylogenetic descent, and that all valid
taxa must be monophyletic also lead to integrative
taxonomy. The recent discovery of extensive hori-
zontal gene transfer among organisms also pro-
vides a significant complication to molecular sys-
tematics (indicating that different genes within the
same organism can have different phylogenies)
necessitating integration of both conventional and
molecular taxonomy for holistic approach.
Molecular taxonomy, on other hand, can facil-
itate easy and rapid identification of the species
provided the gene sequence has been deposited
after authentic identification of the species mor-
phologically supported by all metadata and pho-
tographs. Consistency index of molecular data is
higher than that of morphological data. But ac-
curate identification always comes from the mor-
phological characters and hence addition of the
new species to the list of fauna is encouraged by
conventional taxonomy, which can be supported
by molecular taxonomy. Both approaches have
issues and limitations, which can supplement and
complement for holistic species identity.Table 1 Some methods presently employed in identification of the species. (Adopted from: Singh ( 2012 ))
Methods Explanation
Hybridization Genetic materials from two different species are subjected to hybridize. Closely related
species show higher percentage of hybridization
DNA sequencing DNA segments of two species are sequenced from one end to the other and the
sequences of the two form the basis of establishing similarity or dissimilarity between
them
Restriction mapping Segments of DNA are isolated from different species and subjected to restriction map-
ping. Closely related species will have more similar restriction map
Chromosome banding The chromosomes of different species are examined through microscope. Banding of
chromosomes are also done for taxonomic purposes
Amino acid sequencing Like DNA sequencing, protein sequencing is also done. The amino acid sequence of a
given protein will be more similar between closely related species
Immunological methods Antibodies that recognize specific macromolecules, usually on the cell surface are
tested on different species. Antibodies that recognize macromolecules form one species
will often recognize closely related species, but not from distantly related species