What are we defining as life? The whole idea of a spirit as somehow a necessary distinct item that carries someone's essence and is eternal utterly falls apart when we examine life through a microscope. Individual cells live and die and, like bacteria, can survive beyond the host. Are we pretending that they also have spirits? Will this invisible heavenly realm be populated largely from the very blood cell spirits that (Mormon ) heaven will have determined have no further functional place in the resurrected body ( no blood). If bacteria are somehow to small to have a spirit then at which evolutionary level do spirits turn up, jellyfish, lichen, oak trees, snakes....?
Considering the issue of evolution and Mormon theology that all spirits precede the physical body are you suggesting that spirits in heaven are evolving and that god allocates just enough spirits for each species ( so the dodos were doomed whether the sailors ate them or not) ? The problem doesn't get any better if we start suggesting that god allows certain types of spirits to inhabit multiple species ( a cat spirit in heaven could be in a lion, tiger or domesticated cat for example) because that still struggles with the evolutionary cut off points, where do birdlike dinosaur spirits get the boot and the bird spirits start getting inserted?
Do we let plants have spirits? Do we go as far as Mormon theology does and start ascribing spirits to non living ( according to scientific standards) things like rocks and planets? If you wish Cold Steel we can get a bit further in and discuss what JS really taught about spirit and we can see how incompatible it is with any practical attempt to follow these things through to their logical conclusion.