Departmental Seminar at CES on 3 March 2023 at 3:00 pm titled "A ‘Spectacular’ Saga: reconstructing the evolutionary history of the Indian spectacled cobra" by Paulomi Dam Kanunjna from IISc
Snakes are among the most notable reptilian lineages ubiquitous in several ecosystems across the globe. The innovation of the venom system has strongly underpinned their evolutionary success. Snake venoms are complex cocktails of toxins that collectively facilitate many ecological functions such as predation, defence, conspecific competition, or a combination thereof. Many of these venomous snakes can potentially inflict medically significant envenomation in humans. In India, the Indian spectacled cobra (Naja naja) is one of the “big four” medically relevant snake species that are responsible for most human envenomation and lethality. With a near-country-wide distribution, N. naja is a generalist snake that inhabits diverse ecological habitats. Geographically disparate populations of this species show observable differences in various phenotypic traits, including colouration, scalation, and hood markings, as well as in their venom composition. While the genus has garnered global taxonomic and venom research attention, detailed studies investigating molecular phylogenetics, the population genetic structures, and their influence on venom composition and potency are lacking for the Indian congener, N. naja. Taxonomic re-evaluations have led to the decomplexation of the N. naja complex into different Asiatic species of Naja. The nomen, ‘N. naja’, is retained for the populations present in the Indian subcontinent, with India Orientalis as its type locality. Based on morphological considerations, Deraniyagala (1960) proposed five subspecies of N. naja, which were subsequently rejected by researchers, clubbing them all as a monophyletic group. This synonymization, however, was without molecular evidence. The spatially disparate populations can also be structured into phylogenetic units corresponding to geographical regions and be closely associated with contemporary and historical population dynamics. Understanding the evolutionary relationships of these populations within a phylogenetic framework and assessing the genetic diversity would widen the understanding of the systematics of this medically important group. Even though the phylogenetic pattern by itself is not a good predictor for venom composition, phylogenetic studies can shed light on the underlying patterns of the evolution of the venom of the species. For my PhD, I aim to leverage an integrative approach involving phylogenetics, phylogeography, and population genetics to understand the evolution of N. naja across its range of distribution and the possible geological events responsible for its current distribution. Furthermore, the project will also evaluate the extent of gene flow between the populations and investigate the role of biogeographic conditions and population genetics on the venom composition and, consequently, venom potencies.