The hormone produced by the placenta that stimulates the ovaries to continue producing estrogen and progesterone is called the follicle stimulating hormone. This hormone stimulates the ovarian follicle allowing the egg to grow thus producing continuous supply of estrogen and progesterone.
The system of classification relates to the diversity of species because the system of classification is how we organize the diversity of species. With out it we would have a hard time trying to determine which animals belong with which group. There would be no order, just chaos of trying to determine animal likeness of one another.
To cut this answer short, it helps them organize organisms.
