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    MORPHOMETRIC AND ALLOZYME VARIATION IN NATURAL POPULATIONS AND CULTURED STRAINS OF THE NILE TILAPIA OREOCHROMIS NILOTICUS (TELEOSTEI, CICHLIDAE)
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    Abstract:
    Morphometric and allozyme variation of nine natural populations and three cultured strains of Oreochromis niloticus has been studied. Natural populations from West Africa and the Nile, identified as the same subspecies, O. niloticus niloticus, differed significantly. The Nile populations are genetically closer to the population from Lake Edward, identified as O. niloticus eduardianw. Morphological differences were observed between natural populations and their cultured strains. These are undoubtedly related to ecophenotypic influences, because cultured strains are genetically related to their natural parental populations.
    Keywords:
    Nile tilapia
    Subspecies
    Teleostei
    Genetic Variability
    Variation in phenotype based on morphometric character indices and meristic counts and in genotype based on random amplified polymorphic DNA (RAPD) fingerprinting among different wild and cultured Nile tilapia (Oreochromis niloticus ) populations were analyzed phylogenetically to study and compare the amount of differences in phenotype with the amount of differences in genotype and to help assess the degree of phenotypic plasticity shown by these populations. The results revealed that there were significant differences (P≤0.05) in most of morphometric character indices and meristic counts among different wild and cultured Nile tilapia populations tested. Data of genetic similarity coefficients among four populations of Nile tilapia based on RAPD data of all primers used, showed the highest interpopulation genetic similarity (64%) exhibited between Manzalah and Edku Lake populations, while the lowest genetic similarity (37%) was recorded between Manzalah Lake and cultured populations. The hierarchical cluster analysis based on each phenotype and genotype analysis grouped the four populations into two major category groups: Edku Lake, Manzalah Lake and Nile river populations group and cultured population group. Within these major grouping, wild Nile tilapia were grouped close together. Also, Edku Lake population appears to be more similar to that of Manzalah Lake population than that of Nile river population. Moreover, the great concordance between each phylogeny based on phenotype and genotype analysis revealed that the phenotypic plasticity may not be found in the different Nile tilapia populations tested and the relationship among them considered as intraspecific.
    Nile tilapia
    Phylogenetic relationship
    Citations (11)
    Abstract This study was designed to assess morphological changes between cultured and wild tilapia, Oreochromis niloticus (L.). Wild fish samples were obtained from fishermen operating in the waters of the vicinity of the province Parakou, Benin in November 2014, while the cultured samples were obtained from a fish farm in the municipality of Sô-Ava in the Atlantic region of the southern part of the Republic of Benin. Significant differences were observed in all nine morphometric traits measured. Discriminant analysis of morphometric parameters showed high divergence between the populations. The meristic count, however, overlapped broadly showing no divergence between the populations. The morphometric differences between the cultured and wild tilapia, O. niloticus , could have been linked to genetic differences or environmental factors or a combination of these.
    Meristics
    Cichlid
    Nile tilapia
    Fish fin
    Aquaculture of tilapia
    Citations (5)
    A comparison of electrophoretically detectable isozyme differences in 6 populations of Anopheles quadrimaculatus (sensu stricto) from northeastern Arkansas was undertaken to test the hypothesis that microgeographic variation in habitat types was promoting significant within- and between-population genetic diversity. Genetic heterogeneity within populations was substantial, with all of the enzyme loci examined having 2-7 alleles and average levels of polymorphisms per population between 54.5 and 72.7%. Heterozygotes made up an average over all loci of between 20.6 and 24.8% of the individuals examined. Only weak evidence was found for gametic disequilibrium between pairs of loci. Neither F-statistic nor genetic distance analysis suggested interpopulation divergence. The FST value averaged over loci was 0.190. All Nei distances for pair-wise population comparisons were greater than 0.010, which was much lower than published values from comparisons between populations belonging to different species of the complex. Divergence was not significantly correlated to either geographic distance or habitat type. Examination of the results suggests that little genetic divergence has occurred between populations of An. quadrimaculatus in northeastern Arkansas, possibly because of the dispersal ability and low level of discrimination between oviposition sites exhibited by this species.
    Genetic divergence
    Sensu stricto
    Population Genetics
    Genetic distance
    Sensu
    Citations (1)
    Four populations of Anopheles sacharovi Favre occurring in different ecological subregions at altitudes between 353-1,126 m in the Sanliurfa Province of southeast Turkey were compared using morphometric and allozyme analyses. Four allozyme loci were assessed for genetic differentiation among samples from four localities. The similarity phenogram obtained from the allozyme data showed that populations at Birecik and Sandi branched as a separate group from the Pamuklu and Gedik populations. The Gedik population at the highest altitude (1,126 m) was clustered as a separate branch when linear measurements of 63 morphological characteristics were examined. The UPGMA phenogram also showed that Pamuklu and Sandi formed a cluster while Birecik and Gedik formed separate groups.
    UPGMA
    Geographical distance
    Similarity (geometry)
    Genetic distance
    Citations (10)