American Airlines and Alaska Airlines announced back in February (read more here) that Alaska would join the Oneworld Alliance in the summer of 2021.
The airlines announced then that members of AAdvantage and Mileage Plan would again start earning miles on all flights sometime this spring that is now enabled effective April 1, 2020.
You can access AA's partner page for Alaska here and Alaska's for AA here.
You won't earn elite qualifying miles or dollars and elite bonus miles on Alaska Airlines flights.
Mileage Plan members, however, do earn elite qualifying miles and bonuses on American Airlines flights.
ConclusionIt is interesting to see how this joining of Oneworld Alliance is affected by the global COVID-19 pandemic? It could perhaps lead to delays as airlines will have more pressing issues to deal with, such as staying afloat.
Alaska Airlines frequent fliers earn elite qualifying miles, and rich bonuses for American Airlines flights effective now while AAdvantage members don't for Alaska.