The rainforest ecosystem features dizzying levels of biodiversity, so much so that we can only estimate how many millions of species we still haven't discovered. But the actual reason why the rainforests are so diverse might surprise you.
According to new research from the University of British Columbia and the Smithsonian Tropical Research Institute in Panama (STRI), the specific ecological conditions of the rainforest have almost nothing to do with what makes the ecosystem so diverse. Instead, it's a mix of historical and geological factors. From an ecological perspective, the rainforest is no different from anywhere else in the world, and pretty much anywhere else could theoretically be just as insanely diverse. The rainforest ecosystems just happened to benefit from a geological head start eons ago.
Head researcher Nathan J.B. Kraft explains:
"The same ecological processes seem to be working worldwide. The difference is that tropical organisms have been accumulating for vast periods of time. We see that biodiversity patterns can be explained not by current ecological processes, unfolding over one or two generations, but by much longer-term historical and geological events."
STRI scientist and study co-author Liza Comita adds:
"We found that measurements of variation in biodiversity from place to place, called beta diversity, are actually very similar as you move from the tropics to the poles when you account for the number of species present in the first place."
The research indicates that areas like the forests of Canada and Europe could have just as much biodiversity from a strictly ecological perspective. What did them in is ancient cataclysms like the Ice Age. These extinction events wiped out huge numbers of species and severely reduced biodiversity. The rainforests have so far avoided any such catastrophe, and so their biodiversity has been pretty much always increasing.
Aaron O'Dea, also of STRI, discusses the implications going forward:
"Fossils tell a similar story. Geological history reveals that glaciations and mass extinctions have lasting effects on the structure of biological communities. It bears witness to the devastation that occurs when accumulated biodiversity is lost: a threat we are facing today."