tilapias of the Coptodon subgenus (T. zillii, T. rendalli, T. thollonf, T.
congica, T. guineensis) all have a wide distribution and exclude each other
geographically.
Species of the Sarotherodon group-with the exception of S. galilaeus, S.
niloticus and S. mossambicus--are specialized and more localized; many
species overlap (S. esculentus and S. variabilis in Lake Victoria;S. leucostictus
and S. niloticus in Lakes Edward and George; S. macrochir and S. andersonii
in the Zarnbezi; S. galilaeus and S. niloticus in the Nile; S. niloticus, S. aureus
and S. galilaeus from Senegal to Chad; several species in Lake Malawi). This
overlapping suggests particular preferences and requirements which guarantee
ecological isolation. From this, it follows that a knowledge of the natural
geographical distribution is, necessary to understand the origin of the present
situation by explaining it in relation to the geological-hydrobiological history
of the continent, select intelligently the species to be cultured, and deduce
certain ecological requirements and preferences.Introduction Natural Distribution
............ ......
;:::;:;:; S. galilaeus
A 0 S. melanotheron
####t# S. andersoniiW%tB S. mortimeri.........
. ................. S. spilurus spilurus
E S.spilurus niger
Figure 2b. Natural distribution and introductions of S. galilaeus, S. mossambicus, S. mela-
notheron, S. andersonii, S. mortimeri, S. spilurus spilurus, S. spilurus niger, S. pangani, S.
urolepis, S. ruvumae, S. placidus.
RR5 SEAFnFC1 J,li?RARy
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