Self-fertilization in the white-lipped land snail Triodopsis Albolabris

The breeding system of the polygyrid land snail Triodopsis albolabris was studied in laboratory colonies through the use of allozyme-genetic markers. Isolated virgin individuals self-fertilized only after several months of apparent self-sterility. Isolated pairs appeared to reproduce solely by outcrossing. Overall, the normalized reproductive success of paired individuals was about 86 times greater than that of isolates.
Nine natural populations of this snail were surveyed at eight allozyme loci. All populations were highly polymorphic, and heterozygosity was high and agreed with Hardy-Weinberg expectations. This indicates that selfing is not common in established populations. We conclude that T. albolabris avoid inbreeding by selfing if at all possible. However, if the probability of finding a mate is low (assessed by several months without finding one), lone individuals self-fertilize.