I brought up the issue of sterility in a homozygous spider as well as the possibility of a pre-zygotic barrier to a homozygous spider.

In a spiderXspider pairing, where both parents were produced from spiderXnormal pairings to ensure that they were heterozygotes, we can expect 1 normal, two homozygous spider and one homozygous spider. If the homozygotes were sterile then we would expect 1 in 3spiders produced from the spiderXspider pairing to exhibit sterility, which is what I tried to get across in a previous post.

The existence of a pre-zygotic barrier to a fertilization that would create a homozygous spider seems like a very real possibility based on the data given in regards to follicle count vs. egg count in multiple spiderXspider pairings. Since both males and female spiders can produce viable spider offspring when bred to a normal, it is likely that a sperm with a y chromosme and the spider gene may not have the ability to fertilize an egg, meaning that only gametes with an X chromosome can carry the mutation (an X linked mutation?). This could be proven out by seeing if a male spider can father a male spider. If not, you have your answer, but if so, one would have to dig deeper to find out the reason that no homozygous spiders have been produced.