Assessing morphological diversity and sex genotypes in wild males Nile tilapia (Oreochromis niloticus) populations in Burkina Faso

Nile tilapia is a key aquaculture species and a valuable model for climate change research due to its genetic and temperature-dependent sex determinism. Environmental factors, mainly temperature, induce phenotypic sex reversals, resulting in atypical individuals including XX males. Knowledge of morphological variability and sexual genotype makes it possible to better orient genetic selection programs for this species. The objective of this study is to perform a cross-analysis of the morphological parameters and sexual genotype of male from two natural populations of Nile tilapia in Burkina Faso. The study included 30 males from Lake Kou and 30 males from Lake Tengrela. Sexual genotyping with four chromosomic amh markers revealed 70% XY males, 26.67% XX males, and 3.33% YY males in the Kou population, while the Tengrela population consisted entirely of 100% XX males. A total of 25 metric variables, 6 meristic variables, 3 weight-related with significant difference found in 12, 3 and 2 respectively between XX and XY males within and between the two populations. Principal component analysis (PCA) differentiated XY males (Kou) from XX males (Tengrela) but not XY and XX males within Kou population. Length-weight relationships indicated that XY and XX males from the Kou population exhibited positive allometric growth, whereas XX males from Tengrela showed negative allometric growth. These results are promising for genetic improvement and biodiversity conservation programs for natural Nile tilapia populations in Burkina Faso. They are also a contribution to the understanding of sex determination in natural populations of Nile tilapia.