PHYLOGENETIC-RELATIONSHIPS BETWEEN 21 SPECIES OF 3 TILAPIINE GENERA TILAPIA, SAROTHERODON AND OREOCHROMIS USING ALLOZYME DATA

With the aim of detecting speciation events in Tilapia sensu lato, 24 enzyme loci were studied in eleven species of the genus Tilapia, four species of the genus Sarotherodon, five species of the genus Oreochrom is and five other species belonging to similar genera (Pelmatochrovais , Chilochromis, Tylochromis, Hemichromis and Chromidotilapia). The phy logenetic trees obtained show a clustering of species (except for Saro therodon melanotheron) according to their genera, i.e. Tilapia, Saroth erodon or Oreochromis, which confirms the systematics adopted by Trewa vas. The phylogenetic trees obtained by rooting with species belonging to similar genera confirm the hypothesis that mouthbrooders (Sarother odon and Oreochromis) have a single origin, i.e. egg layers (Tilapia), and negate the hypothesis of multiple speciation of Peters and Berns. (C) 1995 The Fisheries society of the British Isles