How would you best describe the nature of the grammatical error?

Question

Where the lack of a natural predator in Yellowstone National Park has resulted in the overpopulation of bison, deer, and elk.

Answer 1

The word "Where" should not be present.

Answer 2

I agree with Amy P. If you had just "The lack of a natural predator in Yellowstone National Park has resulted in the overpopulation of bison, deer, and elk," that would be a complete and grammatically correct sentence (putting aside the issue of whether or not you actually need the so-called "Oxford comma" after deer and before and).

 

As I see it, one reason you would put where at the beginning would be to create a question, in which case you'd have to put the entire subject noun phrase the lack of a natural predator--i.e., without in Yellowstone National Park, which I'm assuming would be the information that would answer "Where?"--after the auxiliary has, and of course replace the period after elk with a question mark, yielding "Where has the lack of a natural predator resulted in the overpopulation of bison, deer, and elk?" But since your original sentence has neither a question mark nor this so-called inversion of the subject and auxiliary, I'm guessing this isn't the intended use of where. 

 

That leaves the possibility of using where as a relative pronoun, which by definition always introduces a relative clause which by further definition is always a subordinate clause, which by still further definition cannot be punctuated as a sentence by itself in Standard Written English. In other words, which I'm sure you're thanking me for, we could have the sequence of words where the lack of a natural predator in Yellowstone National Park has resulted in the overpopulation of bison, deer, and elk but it would have to be part of a larger sentence like "We discussed the situation where the lack of a natural predator in Yellowstone National Park has resulted in the overpopulation of bison, deer, and elk." In this example, where functions as a relative pronoun whose antecedent, i.e., the noun phrase in the main clause that it refers or is linked to, is the situation. I think most people would then judge this whole sentence as correct, but there may still be some who would object to the relative [excuse the pun] vagueness of the reference of where, that is they might insist that more specific wording like in which should be substituted for where here.

 

Another way to put this would be to say that your original Where the lack of a natural predator in Yellowstone National Park has resulted in the overpopulation of bison, deer, and elk. is a sentence fragment rather than a complete sentence.