EVOLUTIONARY RELATIONSHIPS OF SHINERS IN THE GENUS LUXILUS (CYPRINIDAE) AS DETERMINED BY ANALYSIS OF MITOCHONDRIAL-DNA

In spite of considerable effort, phylogenetic relationships among many members of the family Cyprinidae remain unresolved, and the genus Luxilus remains one of its most controversial groups. In this study, restriction endonuclease analysis of mitochondrial DNA (mtDNA) was used to infer relationships among species of Luxilus, providing an additional character set for evaluating relationships within the genus. Phylogenetic analysis of these data resolved the major groups previously described from morphology and allozymes (the L. coccogenis species group containing L. coccogenis and L. zonistius, the L. cornutus species group consisting of L. albeolus, L. cornutus, L. chrysocephalus chrysocephalus, and L. c. isolepis; the L. zonatus species group containing L. cardinalis, L. pilsbryi, and L. zonatus; and the L. cerasinus species group containing L. cerasinus). Branching order within these groups were well resolved and consistent with previous hypotheses of relationship, with some minor exceptions. The relationships among the species groups (including L. cerasinus) were uncertain. Evaluation of previously proposed relationships of the subgroups within Luxilus relative to the mtDNA data suggests that several of these hypotheses are equally probable, implying that the present data are incapable of resolving phylogenetic relationships at this level of divergence. Correlation between mtDNA sequence divergences and allozyme distances from this and other studies of cyprinids suggests that cleavage site data from the entire mtDNA molecule will most likely be informative for phylogenetic study of cyprinids when mtDNA divergences and allozyme distances are less than 9.5% and 0.20, respectively.