Selfing and brooding in Alinda biplicata (Gastropoda: Pulmonata: Clausiliidae) – life history traits of a good coloniser

Abstract

Alinda biplicata is capable of uniparental reproduction (selfing). The snails need 18 to 24 weeks to reach their ultimate size, and the first reproduction takes place 26 to 39 weeks after shell growth completion. Besides giving birth to juveniles, which is typical of A. biplicata (39% of litters), the uniparentally reproducing individuals laid egg batches (38%) as well as mixed batches (eggs and juveniles; 23%). Within a few days the eggs decomposed, and in mixed batches they were often consumed by the accompanying neonates. In the next season, 70% of the remaining 20 snails reproduced (all of which had reproduced in the previous season). In the first season the neonate:egg proportion was 54:46, in the second 74:26. The egg-laying should be regarded as an anomaly -getting rid of eggs which were not fertilised or in which embryos died at early cleavage stages. The combination of selñng and brooding may explain the wide distribution and wide range of habitats occupied by A. biplicata.

Reproduction, growth and circadian activity of the snail Bradybaena fruticum (O. F. Müller, 1774) (Gastropoda: Pulmonata: Bradybaenidae) in the laboratory

“…However, the snails kept in groups were quicker to form lips (minimum time from hatching to lip formation 2.5 months, compared to individuals kept singly -3.5-6.5 months) [15]. Similar differences in growth rate were observed for Alinda biplicata, where the time needed to reach adult size increased with increasing snail density [38].…”