Animals as well as humans can be self-destructive to their environment

Jeff Gore, a biophysicist at the Massachusetts Institute of Technology, and his colleagues Christoph Ratzke and Jonas Denk, report that when a sample of Paenibacillus sp., a soil bacteria, is fed a diet of glucose and nutrients in the laboratory and allowed to grow at will, the microbes end up polluting their local environment so quickly and completely that the entire population soon kills itself off. It’s not that the microbes had exhausted their resources: Food remained to feed on. But in gorging heedlessly on the glucose bounty, each bacterium had secreted a steady flow of acidic waste into the culture medium, until the ambient pH level had plunged lethally low.

Dr. Gore emphasized that the study was not a recapitulation of how microbes behave in the wild. In the real world of, say, a forest floor, “soil is a tremendously complex environment, with high bacterial densities and diversity and competing interests at play,” he said. Some bacteria are acidifying their neighborhood, while others turn it alkaline and still others expel politely neutral waste. That diversity, Dr. Gore suggested, likely keeps microbial populations from annihilating themselves under ordinary circumstances.

Nature is at best a fickle conservationist, and many animals can prove quite destructive to their surroundings. Flocks of parrots can strip stands of fruiting trees of all their seeds, risking the long-term viability of the very food source on which the birds depend. Elephants are endangered in much of Africa, but in some South African reserves like Makilali they are merry marauders, yanking down trees and denuding all visible vegetation at a dizzying rate.

“It’s no surprise,” said Simon Levin, a theoretical ecologist at Princeton University. “Organisms engage in actions that provide short-term benefits that ultimately can be damaging to the societies of which they are part.”

https://www.nytimes.com/2018/04/30/science/microbes-ecological-suicide.html