title: Distinguishing species.
abstract: Given two organisms, how can one distinguish whether they belong to the same species or not? This might be straightforward for two divergent organisms, but can be extremely difficult and laborious for closely related ones. A molecular marker giving a clear distinction would therefore be of immense benefit. The internal transcribed spacer 2 (ITS2) has been widely used for low-level phylogenetic analyses. Case studies revealed that a compensatory base change (CBC) in the helix II or helix III ITS2 secondary structure between two organisms correlated with sexual incompatibility. We analyzed more than 1300 closely related species to test whether this correlation is generally applicable. In 93%, where a CBC was found between organisms classified within the same genus, they belong to different species. Thus, a CBC in an ITS2 sequence-structure alignment is a sufficient condition to distinguish even closely related species.
authors.affiliation: Department of Bioinformatics, Biocenter, University of Würzburg, Germany. tobias.mueller@biozentrum.uni-wuerzburg.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Müller
authors.forename: Nicole
authors.initials: N
authors.lastname: Philippi
authors.forename: Thomas
authors.initials: T
authors.lastname: Dandekar
authors.forename: Jörg
authors.initials: J
authors.lastname: Schultz
authors.forename: Matthias
authors.initials: M
authors.lastname: Wolf
mesh_terms: D000818:Animals; D001483:Base Sequence / Q000235:genetics; D002965:Classification; D021901:DNA, Intergenic / Q000235:genetics; D005658:Fungi / Q000235:genetics*; D010802:Phylogeny; D010944:Plants / Q000235:genetics*; D017354:Point Mutation; D016415:Sequence Alignment; D013045:Species Specificity
chemical_list: D021901:DNA, Intergenic