Resumen del producto

We explore the trophic role that a diverse sympatric group of fishes in the genus Chirostoma play in a large, shallow lake in central Mexico, Lake Chapala. We use ?¹³C and ?¹⁵N stable isotope - based food web analyses to explore how they relate to other components of the Lake Chapala ecosystem. We find five Chirostoma species in top trophic levels of the Chapala food web compared to other fishes, relying on a combination of zooplankton, fish and benthic resources as energy sources. Food web metric analyses showed generally overlapping trophic niches for members of Chirostoma, especially in terms of ?¹³C. However, C. jordani had lower mean ?¹⁵N isotopic values than C. promelas.As a group, "pescados blancos" (C. sphyraena and C. promelas) also had higher ?¹⁵N signatures than "charales" (C. consocium, C. jordani and C. labarcae) reflecting greater piscivory, but these differences were not strong for all food web metrics used. Trophic overlap among species of Chirostoma in Lake Chapala raises questions about the forces that might have led to a morphologically diverse but functionally similar and monophyletic group of species.

Palabras clave: Pescado blanco; Food web; Shallow lake; Charales; Menidini

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