Perfect Storms Could Be the Key to Understanding Biodiversity

Researchers have been studying the nature of life on Earth and the role of biodiversity. Given the current state of slow biodiversity loss as a variety of species populations are gradually diminishing toward the poles, scientists from the University of Chicago, University of California, Berkeley, and University of California, San Diego try to reconcile two competing ideas that explain this phenomenon in their study published in The American Naturalist.

The first idea states that local environmental factors determine the biodiversity of a given region while the second argues that lineages arise elsewhere and enter into adjoining geographical areas to generate the biodiversity of a given region. In their research, David Jablonski from the University of Chicago and his colleagues from the University of California, Berkeley and University of California, San Diego weigh the viability of both factors work in tandem in the situation of a "perfect storm."

"The gradient involves mutually reinforcing cause, 'perfect storms' rather than a single mechanism," Jablonski explained. "Many of the most dramatic biotic patterns, past and present, are likely to have been generated by diverse, mutually reinforcing drivers, by both local effects and long-term expansions of geographic ranges."

Rare "perfect storms" have a vital role in the the temperate coastlines of southeast Australia and southeast Japan, each of which contains more species than the entire Caribbean region. This could be traced back to the Cambrian Explosion of multicellular life 530 million years ago as well as the overwhelming number diversifications of flowering plants and insects for the last 100 million years. On the other hand, "perfect storms" could also lead to mass extinction as observed at the end of the Paleozoic Era 250 million years ago.

In the study, Jablonski and his team analyzed marine bivalves like scallops, mussels, and cockles. These organisms have become a model system for large-scale spatial and temporal analyses of biodiversity and manifest a strong latitudinal diversity gradient that reflects other groups both on land and sea, while their rich fossil record allows for accurate estimates of origination and extinction.

"Perfect storms" could very well be the key to acquiring better understanding of past, present and future diversity on Earth. The search for unitary mechanisms for the latitudinal diversity gradient is valuable, but the most extreme patterns of biodiversity should take into account diverse, overlapping, mutually reinforcing drivers, the paper concluded.