All three have been subject to legal sanction, so that debate is clearly reflected in our history of governance.
It's not an assumption, it's direct personal observation. I know that you aren't just going to believe me, we are going to have to find data. Actually, as it turns out, there is such data out there. After googling for it for awhile, I have found the keyword that seems to be productive in reaching some of it: "interminority racism". That pulls up results.
I haven't had time to go through it and look to see what is there, but in the little searching I did this evening, I have found, for example, that blacks in the US are more likely than any other group to believe that immigrants take jobs away from existing citizens. There's a variety of other indicators.
I am pretty confident that this is a no-brainer, that minorities, in general, will turn out to be more racist, and less tolerant than the white population, called the "host population" generally in the literature. I guess that in the next little while, if I have some time, I'll start compiling the data and we'll see. I don't think you should count your chickens just yet--although there is not a lot of research on the topic, it does turn out that there is some, and I suspect that the results will disappoint you.
Until I can track down some studies, here's a little light reading:
http://www.economist.com/node/9587776?story_id=9587776
Oh look, now I'm white. My colour keeps changing from thread to thread!