Why can exotic species become invasive?

Step-by-step solution

Although animals eating plants are categorized separately as herbivores, they are, in a broad ecological context, not very different from predators. Besides acting as ‘conduits’ for energy transfer across trophic levels, predators play other important roles. They keep prey populations under control. But for predators, prey species could achieve very high population densities and cause ecosystem instability. When certain exotic species are introduced into a geographical area, they become invasive and start spreading