Meeting Abstract
Phenotypic plasticity is any change in the characteristics of an organism in response to a signal from the environment. These differences in morphology are important because they provide information on survival strategies of organisms. Morphological variation induced by the consumption of different prey seems to be common in fish, expanding the threshold of possible prey in a limited environment. Girardinichthys multiradiatus is a viviparous species endemic to the Lerma river basin, unique due to its confined distribution and abundance. We determined the morphological variation of Girardinichthys multiradiatus induced by two types of diets: Hyalella sp. and Daphnia sp. of two different populations of the Alto Lerma Basin. For the determination of morphology, the captured organisms subjected to two months of experimentation were photographed and analyzed with using geometric morphometry. The results showed that individuals fed Hyalella developed thin bodies, compact eyes, compact heads, thin caudal peduncles and they tend to thin out towards the caudal fin. In contrast, individuals that were fed Daphnia have robust bodies, large eyes, robust heads, robust caudal peduncles and they tend to widen toward the caudal fin. These morphotypes correspond to effective morphologies related to optimal efficiency of predation of benthic and limnetic organisms and to optimal swimming efficiency for hunting them, which shows a plastic response in G. multiradiatus explaining the survival of the species in unfavorable habitats.
