Padrões ontogênicos na ecomorfologia e ecologia trófica de Poecilia reticulata Peters, 1849 (Cyprinodontiformes, Poeciliidae) em um riacho urbano

Abstract

The species P. reticulata has proved to be a r-strategist, standing out for the efficient exploitation of available resources in aquatic ecosystems under environmental pressure. The central hypothesis of this study is that there are variations in the ecomorphological and trophic structures of species throughout your ontogenic development in an urban stream. Two sections of the headwaters of the Cambé stream inserted in the upper Paraná River basin (Londrina-PR, Brazil) were analyzed, in which the limnological and hydrodynamic variables, land use and occupation, as well as ecomorphology and feending of the species were estimated. PERMANOVA was applied to test the existence of ecomorphological and trophic variations throughout the ontogenetic development of the population. The effect of the ecomorphological pattern on the trophic ecology of the species was evaluated by the Mantel Test, while the effect of environmental and hydrodynamic variables on the trophic ecomorphology was tested by the Redundancy and Variance analysis. There was variation limnological and hydrodynamic between the sampling sites, with site 1 presenting higher values of electrical conductivity, turbidity, depth and flow, while site 2 with higher values for water temperature, pH and dissolved oxygen, as well as higher average channel width. P. reticulata showed significant ecomorphological structure between sampling sites, as well as sex and size classes. On the other hand, the trophic structure was significant among all size classes. The Redundancy analysis rejected the null hypothesis of no effect of limnological, hydrodynamic and landscape variables on ecomorphological and trophic patterns throughout the ontogenic development of the species. As ontogenic changes were detected in response to variation environmental between sampling sites, probably due to urbanization, an increase in ecomorphological and trophic plasticity in populations was observed. Juvenile females revealed larger eyes and fins and more protractile mouths, while adults with smaller mouths and eyes and longer, sharper fins, providing bodies better adapted to reach greater speeds to escape predators and to feed more efficiently on resources higher nutritional quality. Juvenile males were shown to have relatively larger heads, mouths, eyes and fins with greater potential for visual acuity and maneuverability, occupying niches near the surface and margin, typically with greater spatial heterogeneity. Therefore, this study demonstrated the predictive potential of ecomorphology and trophic ecology in relation to the adaptive mechanisms of organisms, from the analysis of the interaction among morphology, feeding and environment.