Jisha Krishnan E. K.’s research while affiliated with University of Calicut and other places

Libellulidae are commonly called ‘skimmers’ or ‘perchers’ representing the largest dragonfly family in the world. They are cosmopolitan in distribution and consist of 142 genera and 871 species. This family displays remarkable diversity in behaviour and morphology and consequently focused on studies of comparative population ecology, sexual selection, phylogeography and the evolution of mating behaviour. In the present study we deciphered the phylogenetic relationships of nine Libellulidae members by Neighbour-joining (NJ) and Maximum likelihood methods using partial cytochrome oxidase I gene as the marker. The phylogenetic tree inferred the sister clade relationship of the representing libellulidae members and confirmed the evolutionary divergence in relation with branch length. The averages A+T content of all these species are 62.03 % while G+C content is 37.97 % showing strong A+T bias. The transition/ transversion ratio are found to be 0.858 for purines and 2.533 for pyramidines indicating higher mutations are exhibited by the transition of Thymine, Uracil and Cytosine. The present study thus concluded that the mitochondrial cytochrome oxidase subunit I (COI) gene sequence of Libellulidae members demonstrated substantial variation; therefore it can be used for molecular taxonomy and for the phylogenetic studies.

Ceriagrion coromandelianum commonly called ‘Coromandel Marsh dart’ or ‘Yellow Waxtail’ is a widely distributed damselfly species in South Asia. It acts as a natural ‘biocontrol’ agent against paddy pests like leaf hopper, planthopper, midges and flies. The partial sequence of cytochrome oxidase I gene of C. coromandelianum was analysed by PCR and the result yielded a gene product of 573 bp length. Phylogenetic tree constructed by Maximum likelihood and Neighbour joining method supported with the bootstrap value, taxonomically confirmed the relationship of this species with other damselflies and depicted that it is closely related to C. nipponicum than other Ceriagrion members. Evolutionary divergence and tree reveals that all the Ceriagrion members are having a monophyletic ancestry originating from a common clade with maximum divergence for C. whellani followed by C. nipponicum, C. coromandelianum and C. glabrum and it occurred mainly due to the transitional change of nucleotides.