Has Qantas formed an alliance with Air Canada and United?

Has Qantas formed an alliance with Air Canada and United?

I am currently looking into flights from Australia to Canada and have noticed that many of the connecting flights from LAX to Canada (eg Vancouver, Calgary etc) are now with Air Canada or United.

As these airlines are in the Star Alliance (as opposed to Qantas being in OneWorld) does anyone know why Qantas has stopped using Alaska Airlines and now gone to Air Canada and United?

No.  QF's   partners in the Northern American continent are American Airlines and WestJet.

Airlines normally have interline agreements with many airlines... Air Canada and United are just some of them for QF.  And if you book an Air Canada flight from MEL to YVR, you'll find yourself on QF between MEL-SYD for example. This doesn't mean they are partners - they just sell tickets and through connect bags etc.

QF codeshares on Westjet and Alaskan services to YVR from LAX. AA also now operate on this route, but don't seem to appear on the QF website. If you're after status credits, best to book the QF codeshare or AA flights otherwise you'll get nothing on UA/AC (unless you credit it to a *alliance account).