I want to know the answer to the following question:
What exists in nearly all avian lineages?
All the background I'm provided with is that "While it is agreed that the behavioral and physiological adaptations necessary for migration are under genetic control, some authors have argued that no genetic change is necessary for migratory behavior to develop in a sedentary species because the genetic framework for migratory behavior exists in nearly all avian lineages.". Is that enough to answer the question?
Answer: yes