Apparently not. Consider this interesting passage from The Revenge of Gaia: Earth’s Climate Crisis and the Fate of Humanity, by James Lovelock:
Stable unchanging climates lasting for several thousand years tend to reduce diversity, but when the climate changes to either hotter or colder by a small amount the first response is an increase in biodiversity. This is because the new conditions give rare species a chance to flourish while the established ones have not had time to decline … [I]t is important to keep in mind that biodiversity and environmental quality are not simply proportional … So rich biodiversity is not necessarily something highly desirable and to be preserved at all costs.
This is a very different view of biodiversity than one gleans from most sources, and keep in mind that this is not the view of some nature-hater. Lovelock is the renowned British climate scientist who refers to himself as “a planetary physician,” bent on stopping humans from killing the Earth.
At the very least, the takeaway here is that the push and pull of evolution is endlessly complex — and, of course, endlessly fascinating.