Morphological and molecular analysis of benthic diatoms on intertidal mudflat of the west coast of Korea

Abstract

The benthic diatoms collected from several intertidal mudflat stations of west coast of Korea. We applied morphological and molecular analyses to understand the diversity of benthic diatoms. The molecular analysis of 64 culture strains of benthic diatoms representing 14 genera 56 species performed using two different genes (i.e., nuclear 18S rRNA and plastid rbcL), and the morphology investigated from the selected species. Three groups of diatoms, including nitzshioid, naviculoid and asymmetrical biraphid diatoms distinguished and formed monophyletic groups in the phylogenic tree of each gene. The Bacillaria and Cylindrotheca formed monophyletic group, however, Nitzshia and Tryblionella were polyphyletic group by scattered representative taxa in nitzschioid diatoms group. Naviculoid diatoms consisted of well supported monophyletic groups such as Haslea, Gyrosigma, Pleurosigma and Navicula. Despite morphological features, tube dwelling diatoms Berkeleya and Parlibellus not included in this group but clustered within asymmetrical biraphid diatoms. In asymmetrical biraphid diatoms, Petrodictyon gemma clustered with Surirella. In comparison of divergence of two makers in family level, rbcL gene showed higher divergence level than that of 18s rDNA gene. However, in genus level, divergence levels of each gene were very depending on the taxa included in. The Haslea, Gyrosigma and Entomoneis showed higher divergence level inenthic diatoms representing 14 genera 56 species performed using two different genes (i.e., nuclear 18S rRNA and plastid rbcL), and the morphology investigated from the selected species. Three groups of diatoms, including nitzshioid, naviculoid and asymmetrical biraphid diatoms distinguished and formed monophyletic groups in the phylogenic tree of each gene. The Bacillaria and Cylindrotheca formed monophyletic group, however, Nitzshia and Tryblionella were polyphyletic group by scattered representative taxa in nitzschioid diatoms group. Naviculoid diatoms consisted of well supported monophyletic groups such as Haslea, Gyrosigma, Pleurosigma and Navicula. Despite morphological features, tube dwelling diatoms Berkeleya and Parlibellus not included in this group but clustered within asymmetrical biraphid diatoms. In asymmetrical biraphid diatoms, Petrodictyon gemma clustered with Surirella. In comparison of divergence of two makers in family level, rbcL gene showed higher divergence level than that of 18s rDNA gene. However, in genus level, divergence levels of each gene were very depending on the taxa included in. The Haslea, Gyrosigma and Entomoneis showed higher divergence level in