Which category of organisms is least likely to be revised and why?

In the taxonomic classification of the organism, the species are the categories, which have the most specific traits. In case, a organism is discovered, which has some characteristics similar to any species, then the new organism would be placed in the same genus, but the existing species would not be disturbed. So, the chances of changes in species is least as compared to genus, order, class, phylum and kingdom. So, the species is less likely to be revised.

genetic variation will increase because of a new habitat and food source.

explanation: