Shell coiling in the hermaphroditic snail
Limnaea peregra may be right-handed
dextral) or left-handed (
The coiling depends on the genotype of egg donor parent,
regardless of the phenotype of that parent.
- If that parent is DD or Dd, the offspring will be
The dominant allele (D) produces a gene product that influences spindle orientation in the
first cleavage division of the zygote,
which in turn affects subsequent cell divisions to produce permanent coiling in that direction.