Relative DNA content of somatic nuclei and chromosomal studies in three genera,Tilapia, Sarotherodon,andOreochromis of the tribe Tilapiini (Pisces,Cichlidae) |
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Authors: | K C Majumdar B J McAndrew |
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Institution: | (1) Institute of Aquaculture, University of Stirling, FK9 4LA Stirling, Scotland |
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Abstract: | Seven Tilapiine species from three generaTilapia, Sarotherodon, andOreochromis were cytogenetically studied for chromosome number, chromosome morphology, and DNA content. The chromosome number 2n=44 was
the same in all seven species. Arm number (NF) differences indicate the possible role of pericentric invasions in the karyotypic
evolution of these species. C-banding of metaphase chromosomes shows that heterochromatin is localised around the centromere
in all species ofOreochromis and Sarotherodon butT. zillii has more heterochromatin with six chromosomes having completely C-positive short arms. DNA values vary between 0.84 pq forO. macrochir and 1.21 pq forO. aureus. No heteromorphic sex chromosome pair could be found in any species. These findings suggest that karyotypic evolution has
occurred but does not appear to be associated with speciation in this group. |
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