Novel polymorphism of internal transcribed spacers (ITS) and their utilization in phylogenetic analysis of Neanthes glandicincta (Annelida: Polychaeta: Nereididae).
Sequences of internal transcribed spacers (ITS1 and ITS2) are increasingly being used to infer phylogenetic relationships at or below species levels. Here we report a novel case of ITS polymorphism within Neanthes glandicincta (Annelida: Polychaeta: Nereididae). Two types of ITS sequence (Type I and Type II) were cloned and sequenced, which showed significant differences both in nucleotide composition and length. Variations of these two types sequences also differed from each other with Type I was highly divergent while Type II was highly conserved. Phylogenetic trees inferred from ITS1 and ITS2 sequences showed striking discrepancy in N. glandicincta. Non-concerted evolution of multi-gene is suggested to be responsible for the high degree of polymorphism in ITS regions. Due to the two divergent types of ITS presented within a single N. glandicincta individual, the utilization of ITS regions for delineation of population or closely related species cannot be substantiated. The finding of different types of ITS in a single individual also stresses the need for analyzing a large number of clones whenever ITS sequences obtained by PCR amplification and cloning are being used in phylogenetic reconstruction.
Key Laboratory of Marine-Bioresources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China. pshen@scsio.ac.cn
Ping-Ping
PP
Shen
Hong
H
Zhou
Ji-Guang
JG
Gu
D000818:Animals; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D019143:Evolution, Molecular; D020440:Gene Duplication; D014644:Genetic Variation; D010802:Phylogeny; D011077:Polychaeta / Q000145:classification* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA / Q000379:methods; D013045:Species Specificity
D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer