INVERTEBRATE REPRODUCTION IN ASTATIC WATER BODIES: EGG NUMBER - BODY WEIGHT RELATIONSHIP IN VIVIPARUS VIVIPARUS (L.) FROM OXBOW LAKES

摘要

Reproduction is the most important factor in population dynamics and invading freshwater habitats by Viviparus viviparus. This is largely associated with ovoviviparity of these snails. Some traits like steered reproduction, the appearance of young snails during the whole year, protection of embryos by female and delayed reproduction were fixed by natural selection as adaptations increasing the chance for progeny survival. In variable habitats like oxbow lakes seasonally joined to the river channel, Viviparidae start reproducing in the early stage of their life hence increasing a chance for population to survive.