The journal Nature published a scientific report by a group of biologists, ecologists, and medical researchers that showed the decline of biodiversity allows diseases to flourish. It’s the same kind of phenomena that farmers and forest experts have harped on; lower the genetic variety found in a crop, herd or forest and the greater risk that disease will decimate it. Biodiversity in ecosystems according to the report dampens a pathogen’s ability to spread among humans. By reducing biodiversity worldwide, we are exposing humanity to greater threat from pathogens. The research, which involved 13 authors who reviewed dozens of earlier studies in search of common patterns, found that biodiversity tended to decrease the rate at which diseases are transmitted. It supported this conclusion with evidence involving diseases that ranged from the West Nile virus to schistosomiasis, a disease caused by a parasitic worm that infects 200 million people in tropical countries, to Lyme disease. The studies cited showed that even if the density of the species that play hosts to the pathogens say, white-footed mice in the case of Lyme disease and snails in the case of schistosomiasis remains the same, the spread of disease is less likely in an environment with a greater variety of species. The white-footed mouse is in many ways the Typhoid Mary of Lyme disease, suffering little from any infection itself but readily infecting all the deer ticks that feed on it. Opossums play role. Opossums, native to North America, are “poor hosts for the pathogen, kill the vast majority of ticks that attempt to feed on them and are absent from many low-diversity forest fragments and degraded forests where mice are abundant,” the authors write. Suburban development that reduces forests to small patches tends to have little effect on the mice, the best hosts for the Lyme bacterium, but tends to drive away opossums, which serve as buffers against the disease. Biodiversity in ecosystems is key for humans and all species that live within those ecosystems. Destroying ecosystems through human development is a doomsday device that needs to be reined in.
Photo Credit: John Vlahakis