ROLE OF PARASITES IN EARTH’S BIOSPHERE
Donald A. Windsor
Restriction of monocultures is the basic mechanism operating Earth’s biosphere.
When competition and predation do not control monocultures, parasitic diseases step in. The result is biodiversity and multiple ecosystems.
This simple explanation is based on observation. Monocultures, such as those planted by farmers, are quickly invaded by other species and attacked by numerous pests. Farmers have to be very diligent to protect their crops by using pesticides. Even then, other species manage to invade.
Our biosphere here on Earth is characterized by biodiversity, huge numbers of different species and interactions among all those species. Monocultures are rare and short-lived, found on newly formed islands and on disturbances leading to bare earth.
But what about life on other worlds? Does extraterrestrial life express itself as biodiversity or as monocultures? Do other worldly species interact in ecosystems? Or just dwell in monocultures?
Life on Earth is analogous to human economic forces. Without governmental regulation, unbridled capitalism results in a few very rich winners and vast hordes of poor losers. Our era of the robber barons in the late 1800s and early 1900s is a prime example. Parasites are similar to governmental regulations; they stifle exuberance.
Perhaps a world without parasites would be similar to unregulated capitalism, with a few very successful species and no or very few other species. Perhaps a middle class of species would have developed.
In the near future we may get an opportunity to discover extraterrestrial life. Will it be biodiverse? Or monoculturalistic? If parasites are present, so too will be biodiversity.