Snakes are legless carnivorous reptiles of suborder serpents. They have no eyelids and external ears distinguishing them from legless lizards. All squamates including snakes are ectothermic and amniotic with overlapping scales.

Except Antarctica and some other large island like Ireland, Iceland, Greenland, Hawaiian archipelage and New Zealand islands, snake are found everywhere in the world. Small islands like Atlantic and central Pacific oceans are also covered by snakes. Currently snakes have 20 families with 500 genera and 3400 species. Snake have always been a fear factor, worshipped and loathed in South Asia. Hindus and Buddhists always tell stories and myths about cobras as they accept cobras as sacred. But snakes have always been a pain for millions of people in the world. Even when sufficiently efficient antivenom is available, many of them loose their lives and this makes morbidity and mortality high. Despite of many attempts to figure out exact measure of global snake bites envenoming, this issue is still debatable except some countries.

Out of 300 species of land snakes, only 40 are poisonous in Pakistan. Pakistan is blessed with unique geographical and environmental conditions that bring diversity in local snakes. Molecular biology is helping in measuring genetic diversity and correct identification of snakes which can be helpful in treating snakebites for saving millions of lives. Information on the genetic relationships of organisms is deficient on this unique and distinctive creature. Muhammad Rizwan Ashraf, Ph.D. Scholarat Institute of Biochemistry and Biotechnology, University of Veterinary and Animal Sciences, Lahore under the supervision of Dr. Asif Nadeem conducted a research in collaboration with The University of Texas at Arlington, Texas U.S.A. on “Big Four” (Common Krait, Black Cobra, Russell’s viper and saw-scaled viper) snakes in Pakistan through DNA (Deoxyribonucleic Acid) analysis and molecular biology techniques.Molecular biology has helped mitochondrial DNA studies to give an insight into structure of a population, gene flow, hybridization, biogeography, and phylogenetics. Phylogenetics shows relationships among organism and genes. It gives a clearer picture of biodiversity, biogeography and evolution of many characters in related groups. Evolutionary studies give comparison of mitochondrial genome organization and function while molecular studies help in the improvement of these evolutionary studies. At molecular level, DNA sequencing has enabled scientists to accumulate sequence data and their analysis through computational methods. The aim of this research was to infer the genetic diversity in these four snakes ultimately showing their relationships with other species of the snakes.There are two types of cobras in Pakistan. One is black cobra (Naja naja) while the other one is brown cobra (Naja oxiana). Black cobra is found across southern and eastern Pakistan areas while Northern Pakistan inhabits the brown cobra (Naja oxiana). In this study, one of the samples of black cobra was obtained from Department of Herpetology, California Academy of Sciences, San Francisco. Thistissue sample was labeled and preserved as black cobra from Khuzdar Balochistan in the museum but DNA analysis revealed it as Brown cobra (Naja oxiana). So the identity was corrected. Another tissue sample of black cobra was obtained from Museum of Vertebrate Zoology; University of California Berkeley which was collected from Thatta Sindh Pakistan was confirmed as black cobra (Naja naja) with others from Punjab. So it was shown that Punjab and Sindh has black cobra while Balochistan has brown cobra.

This is the first study from Pakistan that involved Common krait (Bungarus caeruleus) from different parts of Pakistan. No genetic data was available from other neighboring countries about common krait which is why this study was first one about the diversity and phylogenetic relationship of this snake.More morphological and genetic studies from Indian subcontinent are required for more resolution and taxonomic status of this snake.

Generally Russel’s viper is divided into two main groups. One of them is Eastern group and the other is western group. The Russell’s viper from Eastern group is named as Daboia siamensis while western Russell’s viper is named as Daboia russelli. The study showed that Pakistan, India and Sri Lanka have Russell’s viper (Daboia russelli) but DNA analysis showed that Pakistan have different Russell’s viper (Daboia russelli) from that of India and Sri Lanka.This study included saw-scaled viper (Echis carinatus) from different cities of Pakistan and compared them with other species of the genus. Saw-scaled viper (Echis carinatus) from Pakistan and UAE was similar to northern Indian parts and stated as different subspecies (Echis carinatus sochureki) from south Indian saw-scaled viper (Echis carinatus carinatus).

So, this study gives an insight in the genetic biodiversity and phylogenetic relationships of the four venomous snake species of Pakistan showing considerable inter and intra specific variations from different geographical regions of the world. Inclusion of greater number of samples and diverse sampling is recommended for more resolution in the genetic biodiversity and phylogenetic relationships of these snakes so that correct identification with authenticity might help not only in genetic conservation of such species but also in the development of effective anti-venom against venomous snake bites.

The writer is PhD Scholar at University of Veterinary & Animal Sciences, Lahore.