To give you a little bit of history. Originally, after Darwin conservative Christianity denied the possibility of evolution. Species were fixed by God and did not change. Hence the Tennessee law against teaching evolution, as in the Scopes Trial.
Eventually the evidence that species changed grew too much to deny, and the conservative Christian position changed. They latched onto the marcoevolution/microevolution difference and allowed that microevolution might happen, but not macroevolution. At that time, the definition was that micro- was within a species and macro- was a new species or higher clade. Hence creationists denied that new species could evolve, equating biological species to Biblical kind.
Since then evidence has been found for the evolution of species, so conservative creationists switched to Biblical kinds, which can now contain more than one species: horses and donkeys for example or dogs and wolves. Some use “kind” in this sense; others use macroevolution to mean evolution between kinds, which is not the scientific definition. The scientific definition has remained unchanged: new species or higher clade.
Macroevolution (scientific definition) has been observed many times. Macroevolution (YEC definition) has never been observed because there is no agreed objective definition for the boundaries between kinds.
The paper I referred to gave three changes, one change altered the camouflage pattern, so the mutant was more suited to a different environment. The other two changes altered the breeding season, which reduced the chance of crossbreeds, which were not well camouflaged in either environment. All three mutations were beneficial, enabling colonisation of a new environment.