Morphological and meristic characteristics of the intraspecific hybrids of Oreochromis niloticus (TREWAVAS 1983) from three isolated water bodies in Nigeria

Abstract

The pattern of morphological variations among Oreochromis niloticus (Trewavas, 1983) (Cichlidae; Teleostei) from three isolated water bodies in Nigeria (Kainji reservoir in Niger state, Egbe reservoir in Ekiti and Lamingo dam in Plateau) with a view to investigate the genetic diversity using morphometrics and meristics indices.The first principal component (PC1) dominates the dataset, with an eigenvalue of 596.459 and accounting for 99.312% of the total variance. This overwhelming contribution indicates that PC1 effectively captures nearly all variation in the morphometric and meristic data, suggesting a strong underlying pattern or structure. The remaining components (PC2 to PC17) have markedly lower eigenvalues, each explaining a very small fraction of the variance PC2 accounts for 0.25187%, PC3 for 0.16497%, and the last few components (PC15 to PC17) have eigenvalues close to zero, implying negligible influence and likely reflecting random noise in the data. The pronounced dominance of PC1 underscores the potential to simplify the dataset by focusing primarily on this component for analyses and interpretation, reducing dimensionality without significant loss of information. This strong data structure reflects distinct phenotypic patterns among the O. niloticus crosses from three isolated Nigerian water bodies, supporting their morphological differentiation.The research disclosed that there is variation in O. niloticus populations from the three water bodies, which could be a result of genetic structure and environmental conditions, being major factors affecting morphological variability among different geographical populations. Further study on genetic differentiation of individuals from different species is necessary to confirm findings of the present study.