Morphological divergence between two populations of Nile tilapia from Burkina Faso

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Résumé

Nile tilapia, Oreochromis niloticus, exhibits remarkable phenotypic plasticity driven by adaptation to diverse ecological environments. As a major aquaculture species, Nile tilapia is typically subject to strain selection guided by phenotypic variability within natural populations. This study aimed to characterize the morphological variability in two natural populations (Lake Kou and Lake Tengrela) to support selective breeding programs in Burkina Faso. For each population, 50 specimens were analyzed using 25 morphometric variables, 6 meristic variables, and 4 biological indices. Univariate and multivariate analyses identified six morphometric variables, three meristic traits, and three biological indices as the main discriminant factors between the two populations. The results revealed a shared morphological foundation but contrasting phenotypic structures. Indeed, the Tengrela population displayed strong homogeneity, suggesting genetic stability and a predictable response to selection. Whereas the Kou population showed significant intra-population variability, reflecting fine-scale ecological adaptation and high evolutionary potential. These differences indicate a strategic complementarity between the two stocks. The homogeneous Tengrela population offers a favorable basis for establishing pure lines and producing standardized fry, while the genetic diversity within the Kou population represents a valuable genetic reservoir for enhancing the robustness and resilience of local strains. This study provides important data to guide the genetic selection of improved Nile tilapia strains in Burkina Faso.

Mots-clés

Oreochromis niloticus, morphological divergence, morphometric parameters, meristic characters, biological indices, natural populations, phenotypic plasticity, selective breeding, genetic diversity, Burkina Faso