Inferring species-specific molecular markers between morphologically undistinguishable sponges

초록

The phylum Porifera, commonly called sponges, is considered to be an ecologically and economically important of the marine invertebrates, because of being primary targets for marine natural products and pharmaceutical researches. The taxonomical identification of sponges depending on morphological characteristics, however, is very difficult, sometimes even impossible, because of their amorphous (asymmetrical) body forms with a few taxonomical diagnostic charters. To develop genetic markers suitable for species identification, gene sequences of ITS1, 5.8S, ITS2 and COIII were obtained from 12 specimens of four sympartric inter-tidal coastal sponges of Korea and North America. Four species were conspicuously distinguishable in DNA sequences: intra-specific sequence variation was very low (0.000-0.006), but interspecific variations were rather high ( 0.031-0.175). Biogeographical variation was also very low between Korean and North American specimens (variation rate = 0.06). From these results, we concluded that all four species are true species and both regions of ITS in nucleic rDNA and COIII in mitochondrion are suitable for discriminating these cryptic sponge species.