Variação intraespecífica de traços funcionais em peixes de água doce de sistemas lênticos e lóticos do Sudeste do Brasil

Abstract

The intraspecific variation reflects differences in characteristics of the organisms in a given population, and is one of the most important aspects of evolutionary and ecological theories. The aim of this study was to investigate the magnitude and direction of intraspecific variation in fish species between two different types of aquatic systems (lentic and lotic) in Southeast Brazil. Twenty functional characteristics were measured and analyzed in 10 individuals of six species in each system (reservoirs and rivers). The tested hypothesis is that intraspecific variation would be greater in lotic environments because we expect greater variation in species traits of individuals in heterogeneous systems with greater habitat availability. According to the intraspecific coefficient of variation for each trait in each species, intraspecific variation was higher in lentic systems, which is contrary to our initial hypothesis. According to the Analysis of Covariance to test the effect of the lentic and lotic systems in each species, removing the size effect, the traits oral gape, body depth, body width and gut length were those that most differed significantly between the lentic and lotic environments, being frequently greater in the lentic systems. For both lotic and lentic systems, the traits oral gape, pectoral fin height, gut length, oocyte diameter, oocyte number and gonadosomatic index had greater variation at the intraspecific level (Relative Intraespecific Variation > 60% ), whereas the traits eye diameter, pelvic fin length and dorsal fin length varied more at the interspecific level (Relative Intraspecific Variation < 25%). The traits eye diameter, eye position, body width, pectoral fin length, pelvic fin height and length, caudal fin height and length, dorsal fin height and length, anal fin height, and gill raker length had low relative intraspecific variation in both systems and therefore are better to be associated with environmental characteristics.