Seleção de recursos tróficos por Poecilia vivipara, Bloch 1801 em poças intermitentes: abordagem populacional e individual

Abstract

The selection of food resources is directly related to the foraging options . These, in turn, influenced the abundance and scarcity of the resource in the environment that influence the types of interactions between individuals. Extreme conditions such as drought in semiarid environments are responsible for variations in abiotic and biotic variables causing species seek strategies to forage optimally. Another factor that are related to the resource choices by a population is individual variation within a population. The present study focused on the selection of trophic resources by Poecilia vivipara, Bloch 1801 and its relation to predation and abiotic variables (Chapter 1) and the individual especialization of the species (Chapter 2) . Three campaigns were conducted in temporary pools in Poti river in Crateús, Brazil. The collection of individuals was conducted using trawls and availability was checked by collecting samples of the environment . These animals were subjected to analysis of intestinal contents and diversity of macroinvertebrates in the environment was counted and classified . The calculation of electivity index was done to understand the selection of resources and the index of proportional similarity to understanding individual specialization. Regardless of the pool, individuals of P. vivipara exhibited high selectivity for animal items indicating a power in search of the best items, regardless of the abundance or scarcity of the items. The individual specialization was low compared with other environments, but was correlated with the increase in diversity and magnitude niche. Intermittent environment showed extreme conditions and has shown to be the main shaper of selection of food resources on the species.