The movement of individuals leaving from a population is called

you can have just about every answer you can think of

on island x the species needed to adapt because they were being subject to predators which didn't inhabit island y.  

the correct answer is anaphylaxis.

anaphylaxis is a condition caused by insect bites, foods, medications, manifested by tongue swelling, shortness of breath, vomiting, low blood pressure. it sometimes may occur without an obvious reason. it is treated with epinephrine injection.other tretments include antihistamines and steroids,