Occasionally you read in the news that parasite x, plant y or animal z has been found in country abc which shouldn’t be the case and causes problems.
This is often a result of the ongoing climate change, increasing travel and global trade that allows many species to enter into new regions.
Because of the lack of natural predators or competitors, these new species can become locally dominant and replace established species.
My questions: what is the end game?
Will global biodiversity decline significantly to a few “core” species that are flexible in multiple climate zones or environment?
Or will the native species adapt or evolve further?
The rate at which pathogens, predators, etc. evolve to exploit a species is dependent on the size of the species’s population—and once a pathogen anywhere in the world evolves to spread through the species, it can take out the whole population at once.
The more different species fill the same niche around the world, the more likely it is that some of those species will successfully adapt to changing conditions. The local ecosystems with species that don’t adapt might collapse temporarily, but the successful alternatives can replace them and re-diversify.
So reduced biodiverity makes the remaining species and ecosystems more fragile—and species like humans that are dependent on all the remaining globally-distributed monospecies are as vulnerable as all of them combined.