What factors cause ecosystems to tend towards instability?

I have not seen the show you cite, but in general an ecosystem can become unstable in several ways. If a key species is removed partly or completely, it can result in a cascade of changes that could lead to local extinctions of various species. read more

Climate change is a frequent one right now all around the planet. It is also happening world-wide through toxins (like pesticides, herbicides, hormones, antibiotics, and pharmaceuticals. As more sensitive species decline, the whole ecosystem loses its ability to adapt. An ecosystem can be destabilized through isolation. read more