INTRASPECIFIC AND INTERSPECIFIC INFLUENCES ON AGE AT 1ST REPRODUCTION AND FECUNDITY IN THE LAND SNAIL BALEA-PERVERSA

Evaluated the influences of conspecific density and of presence of a competitor (the land snail Chondrina clienta) on age at first reproduction and reproductive output in the rock-dwelling land snail Balea perversa. Age at first reproduction of B. perversa was positively correlated with time to complete shell growth. Both increased with density of conspecifics, indicating intraspecific competition. Presence of C. clienta did not influence age at first reproduction of B. perversa, but both fecundity (number of young produced per adult snail) and reproductive rate (number of young produced per 100 days of adult life) in B. perversa were negatively affected by increased density of conspecifics and by the presence of C. clienta, indicating intra-and interspecific influences. The reduced fecundity of B. perversa was probably caused by conditions experienced during adulthood rather than by the smaller adult size as a result of growth under crowded conditions. -from Author