Before revision:  We confirm this prediction using a simulation model and demonstrate its utility using experimental communities of annual plants . Using this case study, we show thatour hypothesis is more easily falsifiable than the classical species pool hypothesis and could be applied as a null hypothesis to any system.
After revision:  We confirm this prediction using a simulation model to confirm our prediction that directional selection should lead to lower species diversity than stabilizing selection despite a similar effect on trait community-weighted variance. We apply the framework to a mesocosm system of annual plants . Using this case study, we show thatour hypothesis is more easily falsifiable than the classical species pool hypothesis and could be applied as a null hypothesis to any system.