Biomathematics Seminar
Tuesday 1/16/07

Speaker: Kevin Gross
Asisstant Professor
Biomathematics Program, NCSU

Title: Does species diversity drive community production or vice versa? Towards 
a unification of historical and contemporary paradigms

Abstract:

Studies examining the relationship between species diversity and the 
productivity of ecological communities have taken one of two opposite 
viewpoints, either viewing productivity as a primary driver of 
diversity, or diversity as a driver of productivity. Recently, verbal 
and graphical hypotheses have been proposed that attempt to merge these 
perspectives by clarifying the causal pathways that link resource supply 
rates, species diversity, resource use and biomass production. Here we 
present a mathematical model that formalizes how these pathways can 
operate simultaneously in a single ecological system. Using a 
metacommunity model in which classic consumer-resource theory governs 
species interactions within patches, we show that the mechanisms by 
which resource loading influences species diversity are inherently 
linked to the mechanisms by which species diversity controls resource 
use and biomass production. Unlike prior hypotheses, our model shows 
that resource loading can affect diversity and diversity can affect 
productivity simultaneously at a single spatial scale. Our model also 
reproduces scale-dependent associations between species diversity and 
community biomass that have been reported elsewhere. By detailing the 
rich network of pathways by which resource supply rates, resource use, 
and species diversity are connected, our model moves closer towards 
resolving the nature of causality in diversity-productivity relationships.