Probably nothing. There are a lot of vegetarians in California and Australia and Oceania and Asia (mostly Japan and India).
Elephants, who are important grazers, are instrumental in transforming woodlands into grasslands. This has a tremendous impact on other species that depend on the grass for their survival. The significance of the elephant in this example is B. keystone species.
Biology is the study of life, and uses the scientific method, the basis of science, to do so. Hypotheses are made, tested, and remade, until a theory is made, which then becomes Scientific law.