Morphological variation of African snakehead (Parachanna obscura) populations along climate and habitat gradients in Cote d'Ivoire, West Africa

Intraspecific morphological variation may reflect phenotypic plasticity or adaptive divergence. While adaptive shape divergence may occur more likely among isolated populations with reduced gene flow, phenotypic plasticity may reflect morphological responses to heterogeneous environments, even in spatially connected populations. We evaluated both processes while examining morphological variations among seven wild populations of snakehead fish (Parachanna obscura) along climate and habitat gradients in Cote d'Ivoire, West Africa. Morphological variations were studied by multivariate canonical variate analysis (CVA) as based on geometric morphometrics of 15 fish body landmarks. Correlations between shape variations among populations and climate and habitat characteristics and between morphological and geographic distances were calculated. We found significant morphological variations among the seven populations. The variations in fish shape were concentrated on landmarks related to swimming and feeding, suggesting a contribution of environmental variation to morphological differentiation. However, we did not detect significant effects of climate and habitat variables on fish shape. The trend between geographical and morphological distances was likewise not significant. Therefore, a mechanistic understanding of the factors causing shape variation among P. obscura populations in West Africa could not yet be achieved.

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We examined morphological variations among seven wild populations of snakehead fish in Cote d'Ivoire, West Africa. The variations were concentrated on landmarks related to swimming and feeding, suggesting the impact of environmental variation on morphological differentiation. However, there were no significant effects of climate and habitat variables on fish shape. A mechanistic understanding of the factors causing shape variation among the populations could not yet be achieved.