Tim@T-Bonham.net seems to understand that. His objection to me answering with “no” seems to be based on non-domesticated birds also producing unfertilized eggs. It seems he thought my answer of “no” means that I think otherwise- that I think non-domesticated birds never produce unfertilized eggs.
One of the things we didn’t focus on earlier was a good point that HoneyBadger made,
It could well be true that this weakens selective pressure in the wild, but I’d remain skeptical that it’s enough to remove selection pressure altogether. A fully-formed bird egg seems like a big energy expenditure relative to the size of a bird, so I think there would be significant selection pressure to avoid wasting that energy even if it’s rare for ova to remain unfertilized in the wild.
As you say, it’s rare, as most wild birds lay eggs only during breeding season. That rareness seems to have been enough to not have birds wiped out due to the inability of having eggs become mostly developed only after being fertilized. I don’t think there’s any better answer than that. From the last paragraph in the first link:
But a bird’s egg can be thought of as single cell (whether on not some would say the yolk or germinal disc is).
I had a pair and the female kept laying eggs and chucking them out of the nest. I would find them on the floor of the cage. Eventually she began to lose feathers because of the stress of producing eggs constantly.
Sometimes signals just get crossed up, especially in captivity, and animals do maladaptive things.
You’re still missing the point. The cost of producing or losing a mammalian egg is trivial. A bird has invested a large amount of energy in the egg, particularly the yolk, so laying an infertile one is far more costly.
Are you sure? Or have you maybe missed my point? My point is that an egg is already a single cell. How can the bird evolve to have it less developed before being fertilized is my point. I am aware of the nutrition contained in an egg.
Female birds are capable of storing sperm in the reproductive tract, and eggs can be fertilized up to 15 weeks after mating. So it would theoretically be possible for birds not to add yolk to the ovum until after it had been fertilized.
In wild birds? Cite?
What about when the sperm doesn’t last nearly as long? Counting on that is a a better reproductive strategy than the rare laying of unfertilized eggs?
Add yolk to the ovum? So the germinal disc would just be hanging around and it would attach to yolk that gets injected later somehow, and survive fertilized in the mean time? Germinal discs form ON yolks. The ovum with its yolk moves down the oviduct right after fertilization and the yolk provides nourishment immediately. I don’t see how anything you’re saying is “theoretically” possible, other than that being synonymous with “if everything about birds were different, it would be possible.” Great. What I actually hear you saying is “I’m not going to admit that maybe your point was valid.”