RAPD-PCR investigations of systematic relationships among four species of eels (Teleostei : Anguillidae), particularly Anguilla anguilla and A-rostrata

We examined the genetic identities of 49 individuals of four species of eel s in the genus Anguilla Shaw, A. anguilla, A. japonica, A. reinhardti and A . rostrata, using the random(ly) amplified polymorphic DNA (RAPD)-PCR techn ique. We used 15 random decamer primers. Out of the 22148 amplification pro ducts detected, 454 markers were evaluated using Nei's distance coefficient , two numerical methods (neighbor-joining, UPGMA), and phylogenetic analysi s using parsimony (PAUP). Both numerical and parsimony methods were congrue nt and confirmed the specific status of all four examined Anguilla species. In all dendrograms, all individuals of each of the species clustered toget her within four closed groups with highly significant bootstrap values (bet ween 97 and 100%). Additionally 1 to 18 species-specific monomorphic diagno stic fragments were detected in three of the species; none were detected in A. anguilla. Mean interspecific genetic distances ranged from 0.384 to 0.5 59, with the minimum between A. anguilla and A. rostrata and the maximum be tween A. anguilla and A. reinhardti. Individuals collected at one locality and belonging to a single species did not cluster together, and neither wer e any diagnostic monomorphic fragments found for individuals of single loca lities. This probably reflects a random dispersal of larvae in ocean curren ts before they reach coastal waters. Among all possible species pairs, only the two Atlantic species were consistently clustered in all dendrograms, w ith highly significant bootstrap values (100%). Additionally, we detected t en diagnostic markers for this pair of eel species. From RAPD data, we sugg est a phylogram which was routed by the descending analysis method: A. rein hardti appears to have been the first species to diverge from a putative co mmon ancestor of the four eel species. Later, A. japonica separated from th e hypothetical ancestor of the Atlantic species, which then split recently into A. anguilla and A. rostrata. The close relationship of A. anguilla and A. rostrata is indicated by their low genetic distance (GD = 0.384) and a high degree of shared RAPD fragments (SF = 71.2%); this compares with the f ollowing means for all other species pairs: (<(GD)over bar> = 0.531, <(SF)o ver bar> = 44.2%). The prerequisites for using RAPD data for the reconstruc tion of phylogenies are discussed.