DNA Barcoding of Earthworms of Coorg Region of Karnataka, India and Study of Their Physio-Chemical Habitat

Abstract

Earthworms are considered as biological indicators of soil fertility and are the major macro fauna of soil. DNA tags are done to identify individuals belonging to the same species, as well as to distinguish between individuals from different species. In the present work, the earthworm fauna was investigated from three Taluks namely, Somvarpet, Virajpet and Madikeri of Coorg, a district situated in the south western part of Karnataka, India. This is the first scientific report on the earthworm species of Coorg and the physio-chemical properties of their soil. The physio-chemical characteristics of the soil were examined and DNA barcoding technology was used to identify the taxonomic status of earthworms. A total of 38 earthworm samples were collected, 30 of which were amplified using mitochondrial Cytochrome Oxidase subunit1 (CO1) gene specific primers. The sequencing data were deposited into Genbank and assigned to accession numbers (30 Accessions). The maximum likelihood technique was used to create the phylogenetic tree. Kimura's two-parameter model was used to calculate pairwise genetic distance. DNA barcoding results showed that Pontoscolex corethrurus was the most common earthworm species in Coorg. Progizzardus varadiamensis, Glyphidrilus annandalei, Amythas sp., Metaphire megascolidioides, Dichogaster bolaui and Acanthodrilidae sp were also observed. From the findings, it is observed that the mean pH of Coorg soil was found to be 6.2 with an electrical conductivity of 0.28 dS/m. Coorg soil contains a moderate level of Organic Carbon (O.C) content with an average of 1.74%. Thus, the study included extensive descriptions of earthworm species, as well as their DNA barcodes and the physio-chemical characteristics of their habitat, which help with future species identification.