História de vida de Bulimulus tenuissimus (d’ Orbigny, 1835) (Mollusca, Bulimulidae): variação no conteúdo dos substratos energéticos de acordo com a idade e sazonalidade

Abstract

There are few studies about land snails despite their importance and diversity, especially native species, such as Bulimulus tenuissimus. Thus, the objectives of this study were to describe the life history of this species evaluating the growth, reproduction and longevity. The influence of the isolation on these aspects, the change of energy resources in different ages and in different seasons were evaluated. For this purpose, there was monitoring the biological cycle of 240 snails, of which 120 were kept in groups and 120 were kept isolated during their lifetime. Bulimulus tenuissimus showed plasticity in the allocation of energy between growth, reproduction and survival. Growth of isolated snails was higher fecundity and longevity than the animals kept in isolation. However, the growth was high in isolation. Thus, the differential energetic investment has lead to distinct patterns of life history. The age influenced the allocation de glycogen and galactogen. However, there was not reduction of glycogen content in the digestive gland. It is suggest that the energy used in reproduction is acquired from food ingestion. There were seasonal changes on the contents these polysaccharides, which are coincident with the reproductive cycle of B. tenuissimus. This result showed that the reproductive seasonality of this species would be controlled by metabolic factors.