One of the greatest threats to biodiversity in an ecosystem is the introduction of non-native species. If biodiversity improves the chances that life in the ecosystem will survive into the far future by not having most of it susceptible to a small range of threats, dominance by a single (or limited number) of species makes it far more likely that life will have a shorter lifespan. In addition, critical functions performed by extinct or weakened native species will not be performed, increasing the vulnerability of the ecosystem.
We humans, in addition to being the greatest agent of the introduction of invasive species (accidental or on purpose), have become the world’s most successful invasive species. In the HIPPO acronym that describes our influence on biodiversity (Habitat, Invasive species, Pollution, Population, and Over-harvesting) all but the “I” applies to our own role as an invasive species. Taking over habitat or fouling it with our waste and using other species as “resources” to the point of their extinction has drastically reduced biodiversity; and the loss of those other species is now being felt, especially in alteration of the climate and lack of protection from weather events like hurricanes.
Applying an industrial model to agriculture has decreased the number of species we depend on for food and increased our susceptibility to starvation as a result. Partly in response to the threats to our limited food species, we have begun creating radically new invasive species using biotechnology. Genetically modified organisms (GMOs) may end up doing far more damage than good as a result.
In an ideal world where the long term survival of life is a goal, we will need to examine our apparent desire for simplicity in the environment and accept the possibility that lack of direct control over it (and its attendant dependence on our own limitations) may be a good thing. As a result we may, as a species, have to consciously determine what niche or niches we will occupy in a world we can not and should not dominate along with the small number of species we are comfortable with.