Wolf to Dog evolution is still an intensely debated subject and has always been fascinating to me although a little frustrating as each new DNA study seems to contradict some findings of the previous one. They agree as far as dogs came from wolves but not if it was a single event or group of events from one region and species of wolf, or happened in multiple locations from different wolf populations. It's apparently confused as the early wolf-dogs easily crossed with other and perhaps different populations of wolves.
Interestingly Darwin himself believed dogs come from not wolves alone but had multiple (probably other canid) ancestors.
Darwin [
5] stated that 'I do not believe, as we shall presently see, that all our dogs have descended from any one wild species'. Rather, he suggested that domestic dogs 'descended from several wild species'. Phylogenetic analyses derived from molecular markers support an origin of the domestic dog from one ancestor, the wolf (
Canis lupus), thus refuting Darwin's hypothesis ([
11,
22]; Figure
1).
A belief some apparently still hold today
If dogs are descended from wolves, then explain chihuahuas
Chihuahua lineage in particular has long been debated with various theories presented including decent from small dogs kept by the Mayans/Toltecs and Aztecs. Having come from an interbreeding with Fennec Foxes. And whether they come from Asian stocks (came over with first people into the Americas) or European stocks.
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The Fennec fox connection was disproved by one study but the Asian or European linage is still debated. I think it is hampered currently by the limited number of older/ancient samples and that should improve over time.
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