Biology and reproduction of the freshwater snail Melanoides tuberculata (Gastropoda: Prosobrancida) in Israel

This study describes the biology and reproduction of several isolated populations of Melanoides tuberculata found in various water bodies in Israel and the Sinai Peninsula. Although these snails are described as parthenogenetic, we find that some populations in Israel contain 20-33% of males producing motile spermia, while other populations consist only of females. In all populations the offspring are incubated in brood-pouches. The length of incubation is correlated to population density. Electrophoretic studies of esterase (two loci) and acid phosphatase isozymes show that the observed distribution of genotypes within some of the snail populations are in good agreement with the HardyWeinberg expectation. As offspring of single females bear proteins not found in the mothers, we conclude that fertilization occurs within the population.