Hey there! Thanks for writing in!
This is what I could find on ancestry.com:
If you have Native American DNA, it will appear in your ethnicity results as the Indigenous Americas region (whose boarders with Mexico where different than todays).
For help researching indigenous American ancestry, see Researching Native American Ancestors.
The AncestryDNA test is not intended to be used as legal proof of Native American ethnicity.
And, this might be of interest to you too: Indigenous American ancestors and DNA
Anyone with even a single indigenous American ancestor has indigenous American ancestry, but not everyone with an indigenous American ancestor has indigenous American DNA. Only half of a person’s DNA is passed on to their child, so with each generation that passes, the potential exists for DNA from any given ancestor to be lost.
The closer an ancestor is to you, the more likely it is that their DNA has been passed on to you. If your great-grandmother is 25% indigenous American, your original indigenous American ancestor was your great-great-great-grandparent. Although about 12.5% of your DNA comes from your great-grandmother, you may not have inherited her indigenous American DNA, or you may have inherited such a small amount that it doesn’t appear in a DNA test.
Though a child receives 50% of each parent’s DNA, they do not typically receive 50% of each ethnicity present in the parents. A parent with half Nigerian and half indigenous American DNA may pass on more Nigerian DNA than indigenous American DNA (or vice versa) to the child. Over generations, the randomness of inheritance results in DNA from some ethnicities being passed down more than others and in some ethnicities being lost entirely.
And, these links might be of interest to you too:
Researching Native American Ancestors
Hope this helps! And, best of luck!