Population structure and dietary plasticity of four invasive populations of the topmouth gudgeon Pseudorasbora parva

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AbstractThe topmouth gudgeon Pseudorasbora parva is one of the worst invasive species worldwide and is considered to be highly plastic in terms of its phenotype but also behavioral ecology. Here, we analyzed the population structure and the morphological and dietary plasticity of four populations of P. parva across the four seasons within the Arno River basin in Central Italy. We found that the studied populations were morphologically different, suggesting multiple introductions or adaptation to different environmental conditions. In all populations, males were bigger and, overall, more frequent than females. The gonadosomatic index showed a similar pattern across all populations, with higher spring and summer values, indicating a long reproductive period. The diet of P. parva considerably varied across populations and seasons, suggesting a high degree of spatio‐temporal trophic plasticity. Diet breadth varied among seasons, being more specialized in spring and summer and more opportunistic during autumn and winter. Our results highlight high trophic plasticity in the invasive populations of P. parva, potentially impacting multiple native taxa.