I would say immigration only.
emigration would theoretically reduce the genetic variation as unique individuals leave, but immigration would bring unique traits into circulation in an ecosystem.
I'm not super great at biogy tho so this might not be right... :)
Answer;
The amnion
Explanation;
-The amnion is a tough, thin membrane that surrounds a developing fetus in mammals, reptiles, and birds. It is the first of the three cavities (amnion, chorion and yolk sac) in the embryo and is formed on 8 dpc.
-In the human body, the amnion is the first of three cavities, including the chorion and yolk sac, that work together to keep the developing fetus nourished and protected.
-The amnion provides a protective environment in which the fetus' temperature is regulated and protects the fetus from friction caused by the mother's movements.
First one is digestive system
second one is lion fish
i dont know the third one. im sorry