Life history of Bulimulus tenuissimus (D'Orbigny, 1835) (Gastropoda,Pulmonata, Bulimulidae): effect of isolation in reproductive strategy and in resources allocation over their lifetime

Despite the great diversity of tropical land snail species, the life history strategies of the great majority of them are unstudied. We studied reproduction, growth and survival patterns of the Brazilian species Bulimulus tenuissimus (D'Orbigny, 1835), and verified the effect of isolation on such patterns. We analyzed aspects of the life cycle of snails maintained in groups and in isolation. For both treatments, we determined the duration of the juvenile, adult and senescent stages. Growth pattern, life-time reproductive output, reproductive output during adult and senescent stages and longevity, were also verified. Isolation prolonged the duration of the juvenile stage, causing a decrease in life-time reproductive output and longevity. The reproductive pattern of the species is seasonal and, in grouped snails, three breeding periods occurred during their lifetime. The isolated snails reproduced by self-fertilization, and only reproduced once in their lifetime, indicating a significant change in reproductive strategy in the isolated individuals. Thus, isolation resulted in changes in energy allocation to growth, reproduction and survival. The results indicate that in adverse environmental conditions, life history traits can enhance the capacity for adaption.