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DNA profiling of Tilapia guinasana , a species endemic to a single sinkhole, to determine the genetic divergence between color forms
Author(s) -
Nxomani Clifford,
Ribbink Antony J.,
Kirby Ralph
Publication year - 1999
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/(sici)1522-2683(19990101)20:8<1781::aid-elps1781>3.0.co;2-z
Subject(s) - biology , tilapia , outbreeding depression , sinkhole , genetic divergence , evolutionary biology , population , zoology , karst , genetics , ecology , fishery , genetic diversity , inbreeding , fish <actinopterygii> , demography , paleontology , sociology
Northwestern South Africa and Namibia contain a number of sinkholes in the dolomitic rock formations found in this area. These contain isolated populations of Tilapia . Most contain Tilapia sparmanii , but the one in Namibia, Guinas, is of particular interest as it contains the endemic species, Tilapia guinasana , which exhibits none sex‐limited polychromatisms, which is unique for Tilapia . This sinkhole is under environmental threat, particularly as a result of being a recreational diving site. This study, using randomly amplified polymorphic DNA sequences (RAPDs), when analyzed using analysis of variance (ANOVA), shows that the colour forms of Tilapia guinasana are genetically distinct. This confirms previous evidence that assortative mating between color forms takes place. The various possible hypotheses for the occurrence and genetic stability of the color polymorphism are discussed. Further, a new hypothesis is put forward based on a need to maximize outbreeding in fully isolated population with no possibility of increase in size above the maximum and limited carrying capacity of the sinkhole.