This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The spectacled cobra (Naja naja) is one of India's "big four" snakes responsible for most serious snakebite cases. It is currently considered one species, which lives across much of South Asia, with regional differences in color, hood markings and venom.
However, it's still unclear which regional cobra populations represent separate evolutionary groups. A new study published in Molecular Phylogenetics and Evolution has helped parse out which groups have different lineages, and when and where they may have diverged from their ancestors. Early classifications divided spectacled cobras into regional subspecies, but later work treated them as one species.
In particular, a 2022 study proposed that Sri Lankan cobras should be recognized as a separate species. However, a subsequent reassessment challenged this study due to its reliance on mitochondrial markers, limited geographic sampling and the use of venom as taxonomic evidence. The authors of the new study write, "Unfortunately, most molecular studies of N. naja have included samples from Bangladesh, Nepal, Pakistan and Sri Lanka, with minimal representation from India.
This gap likely reflects the persistent challenges associated with obtaining research permits and biological samples for Indian snakes. "However, considering that Indian populations occupy the majority of the species' range, the limited sampling indicates a gap in the phylogenetic assessment of N. naja. Moreover, before this study, only 23 sequences from N. naja were generated, limiting the precise reconstruction of phylogeographic history and phylogenetic diversity." To better understand the phylogenetics and phylogeographic history of the spectacled cobra, the researchers sequenced nine DNA markers, including both mitochondrial and nuclear markers, from scale samples collected from 67 cobras across major Indian regions.
They combined their data with published sequences, including samples from neighboring countries, to reconstruct relationships, estimate split dates and model ancient movements. Results showed that the mainland cobras shared an extensive set of genetic variants and had no clear regional evolutionary divisions detected across India. The researchers say this pattern is consistent with widespread genetic mixing, even with the many differences in appearance and venom across India and nearby regions.
Data from one group stood out, however. The Sri Lankan cobras appeared to form a distinct genetic lineage. The team says that the Sri Lankan and mainland cobras still fall within one species, though, and that genetic differentiation alone does not settle species status.
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