Three tilapiine species belonging to the endemic Lake Malawi species flock known as 'chambo'
Oreochromis (Nyasalapia) karongae, O. (N.) lidole and
O. (N.) squamipinnis and the species Oreochromis (Oreochromis)
shiranus were collected from the wild. These four species were analysed at 43 enzyme
loci using starch gel electrophoresis. No significant deviations from Hardy-Weinberg equilibrium
were observed after correcting for multiple simultaneous testing. The expected heterozygosity
(H-e) was lowest in O. (O.) shiranus (H-e=0.082). The three chambo species
had higher levels: H-e=0.103 to H-e=0.116. The three chambo species as a whole were polymorphic
(99%) at 16 different loci sharing 10 of these in common. No fixed differences between the
three chambo species were observed but highly significant allele frequency differences existed
between all the chambo species. The F-ST calculated for the three chambo species was 0.051,
closer to intra-specific than to inter-specific levels. O. (O.) shiranus
could be clearly separated from all chambo species at five fixed loci. Comparison of the
allozyme data from these species with five species from the same sub genera support the
hypothesis that the chambo form a monophyletic group and that O. (N.)
macrochir or a related species represents the sister taxon.