I really am quite ignorant of the python reproductive cycle. At what point does the egg cell become associated with the follicle? Is ovulation when the egg cell gets paired up with the follicle? The egg cell is already fertilized then, right? Maybe homozygous spider is homozygous lethal before ovulation so only non-homozygous spider fertilized egg cells are available to use up all the available follicles. True, there should only be 66% spider offspring from spider X spider with this scenario but 78% might not be that statistically significant an over represented in this sample size and maybe spider sperm have an advantage in fertilizing egg cells anyway.