Model successfully predicts large river system fish diversity

Controversial 'neutral model' used

While scientists have developed methods to predict aspects of fish diversity in specific river locations, a model to understand what factors may drive a comprehensive suite of fish biodiversity patterns in a large and complex system of rivers has been elusive.

Now a group of researchers, including University of Maryland ecologist William Fagan, reports success using a so-called “neutral model” to study fish diversity in the sprawling Mississippi-Missouri River System. Their study appears in the May 8 issue of Nature.

According to Nature, “That a simple model with a minimal set of parameters can capture the observed biodiversity patterns in complex landscapes suggests that effective monitoring of environmental change is possible, and could contribute to resource management and conservation strategies.”

“The neutral model approach means that we do not need to have detailed knowledge about the competitive hierarchy or species interactions within a group of organisms to quantitatively reproduce a wide variety of biodiversity patterns in that system,” said Fagan, co-principal investigator of the study. “This 'pattern oriented modeling,' in which we simultaneously reproduce a wide variety of empirical results using a single model fit, is a powerful approach for analyzing complex systems.”

Controversial Method

Using the neutral model, in which all species are assumed to be functionally equivalent, to predict biodiversity has been controversial in ecology circles.

“Neutrality is a 'hot' topic in ecology, because it flies in the face of decades of detailed studies of how species interact among themselves on local scales,” says Fagan. “The application of the neutral model to a complex, hierarchically structured spatial network like the Mississippi-Missouri River System is new.