You will need to evaluate the effects of the other variables, such as the effect on climate, perpetuation (of the specie) and above all how "easy" for a top animal to gain all its needs of the surroundings. Has the animal been succesful in survival? Does he have a clear advantage?
Maybe the studies conducted would be amongst population genetics, statistics and maybe in terms of Darwin, even though it is not very precise.
I think they are people that can explain this better.