Diversity of green and red macroalgee distributed in indian west-coast using morphometry and DNA barcoding

Abstract

Modern algal systematists exploit genetic tools for molecular assisted alpha taxonomy and DNA barcoding is one such molecular tool that relies on the use of a standardized DNA region as a tag for rapid and accurate species identification. In this study Nuclear Internal Transcribed Spacer (ITS) was used as a marker for identification and phylogenetic analysis of marine green and red macroalgae in Indian subcontinent. Using Bayesian Inference for phylogenetic reconstruction with T3P model of molecular evolution and gamma distribution (T3P+G) using ITS dataset revealed that the bloom forming Ulva intestinalis found in west coast of Indian subcontinent showed strong endemism, supporting the view that that the genus Ulva encompasses a number of endemic cryptic species in addition to cosmopolitan species. Although there were two morphotypes present in Indian isolates, they constituted a single clade with robust Bayesian Posterior Probability support, confirming conspecificity of these morphotypes. Our results also indicate latitudinal gradients in the distribution of tubular Ulva, with a clade encompassing all nontropical isolates. Higher genetic heterogeneity of tropical isolates as evidenced by highest within-group T3P (Tamura-3-Parameter) distances comparing with that of non-tropical isolates is suggestive of tropics being the geographic origin of these species. While U. compressa and U. intestinalis were monophyletic within nontropical superclade, these morphotypes were polyphyletic within the tropical clade. Due to the polyphyly of currently accepted morphospecies concept and formation of distinct phylogenetic clade among Indian isolates forces us to propose a new bloom forming species of Ulva paschima. Further molecular assessment of invasive Carrageenophyte Kappaphycus alvarezii using ITS-1 region showed affinity to phylogenetic clade of mixed geographical origin confirming that the species was introduced in the subcontinent by human intervention. Surprising result of our study was an endophytic green algae Ulvella leptochaete that was found growing inside Caldophora glomerata, a first report of its kind from India.