Phylogenetic Divergence in the South Torrent Catfish, Liobagrus mediadiposalis (Pisces; Amblycipitidae) of Korea

Abstract

We examined intra-specific phylogenetic relationships in the south torrent catfish, Liobagrus mediadiposalis, in seven major Korean rivers (Geum, Nakdong, Nam, Seomjin, Yeongsan, Mangyeong and Buryeongcheon) based on two different mitochondrial genes: the 16S rRNA and the cytochrome b. Analysis of sequence variation in a 750 bp segment of the mitochondrial cytochrome b gene revealed deep divergence among populations (similarity of 97.9%-99.7%) and high genetic divergence from geographically isolated populations. Intra-specific variation in this 752 bp segment of the 16S rRNA gene sequence was very low and nearly identical. Seven isolated populations of L. mediadiposalis showed a high similarity (98.7%-100%). The 16S rRNA gene sequences were more highly conserved than the cytochrome b sequences among the seven populations. Based on the phylogenetic tree, three genetically distinct clades were identified within this species, one clustering of Geum and Mangyeong rivers group, Seomjin and Yeongsan rivers group and the other clustering of Buryeongcheon, Nam and Nakdong rivers group. In spite of the unique morphological characters in the caudal fin of the Seomjin populations, no remarkable difference was detectable in the 16S rRNA gene and cytochrome b gene sequences from other conspecific populations.