DNAbased marker systems and their utility in entomology

Morphological differences and similarities have been used to group and classify organisms, such as insects, into major taxonomic groups. However, discerning finer differences among strains, races and biotypes is usually difficult due to the influence of environment. Protein-based marking of individuals was used extensively before DNA-based markers were employed. Variation at the DNA level is remarkable, and the unit change is heritable in a simple manner. At present, many DNA-based marker systems are available to address specific questions, both in basic and applied entomological research, that can circumvent the limitations of conventional approaches to a large extent. DNA-based markers, being neutral to environmental influence and abundant, have helped understand genetics of complex traits in animal and plant systems. The present review primarily aims at familiarizing the DNA-based marker systems along with their utility. The techniques described include restriction fragment length polymorphisms (RFLPs), randomly amplified polymorphic DNAs (RAPDs), amplified fragment length polymorphisms (AFLPs), microsatellites/simple sequence repeats (SSRs), expressed sequence tag (EST) based marker system, single nucleotide polymorphisms (SNPs) and other derived marker systems along with their genetic nature and relative comparison