Via West Hunter.The Tibetan Mastiff can take high altitude better than generic dogs. . . . The Tibetan Mastiff picked up some of those useful variants from local wolves, even though the amount of admixture wasn’t large. . . .Naturally you are now worrying about sad Inca puppies – did they suffer from hypoxia? There are canids in South America, like the maned wolf and the bush dog, but they are probably too divergent to be able to hybridize with dogs. The chromosomes are different, so pre-Columbian dogs probably couldn’t acquire their alleles. Moreover, the dogs of the Amerindians seem to have done poorly in competition with Eurasian dogs: I know of only a few breeds [the Carolina Dog, for example] that are known to have significant pre-Columbian ancestry. Perhaps Amerindian dogs were also scythed down by Eurasian diseases.
I don't have the answers, but the questions are good ones.