Phylogeny and Genetic Divergence of Indian Himalayan Population of Anomala dimidiata (Coleoptera: Scarabaeidae) Inferred from Mitochondrial DNA Sequences

摘要

Anomala dimidiata, a key white grub species associated with substantial crop losses in Indian Himalayan region, belong to one of the largest genera under scarab tribe, Anomalini. This paper presents the molecular variation and phylogenetic relationship of this species from the region using partial cytochrome oxidase I (COI) and cytochrome b (cyt b) sequences of mitochondrial genome in both nucleotides and polypeptides. The COI sequences were compared with available five sequences of A. dimidiata and12 sequences of species under genus Anomala to study the divergence within and between species, respectively. However, cyt b sequence, as we were presenting for the first time, was compared with cyt b sequences of Drosophila yakuba whose entire mitochondrial genome was known and Dasylepida ishigakiensis, a scarabid white grub species, whose partial cyt b sequence is available. Both the genes were A + T biased and showed differential codon usage between species and geographical isolates. This is evidenced by discrepancies between nucleotide and deduced polypeptide sequences. The phylogenetic relationship of COI sequences also revealed that A. dimidata was evolutionary associated with A. xanthoptera. The evolutionary distances of three cyt b sequences showed that differences were larger than expected based on evolutionary divergence. The study illustrates a complex genetic variation coupled with highly structured evolutionary divergences between and within species of Anomala.