Before revision:  Second, we propose a general model which encompasses all previous models . We show that our model recovers all previous models' results under identical assumptions. However, most importantly, we also show that, when relaxing some of their hypotheses, previous models give rise to degenerate food webs.
After revision:  Second, we propose a general model encompassing most previous models which allows to show that relaxing arbitrary assumptions gives rise to unrealistic food webs.