Summary of model (2) equilibria, with their positiveness and stability conditions.

All conditions are necessary and sufficient conditions except those marked with an exclamation mark, which are only sufficient conditions in general. The expressions of are given by equations S5, S7, S13, S14 in S1 Text, respectively. The exclamation mark means that we have no explicit conditions in general. The meaning of the parameters can be found in Table 2. The “extra” stability conditions are those that are not redundant with the positiveness conditions.