If mutations arise that affect shell thickness within a snail population then with crabs present those mutations:

both male and female gametes are produced by meiosis of the germ cells. therefore, both male and female gametes are haploid. one male and one female gamete unite during the fertilization to form the diploid zygote. in seed bearing plants, pollen grain is the male gametophyte, which produces sperm cells.

this is more of a statement than a question. is there answers to go along with this, or is it opinion based?