Changes in mean temperature can generate alternative patterns of species coexistence
With the knowledge that combinations of different temporal scales of environmental variation do not have a uniform or consistent effect on species coexistence, the final question we ask is whether mean temperature itself affects patterns of species coexistence (Fig. 4). The previous coexistence-exclusion-coexistence result occurs at a mean temperature (20 degrees) that lies in between the optimal temperatures of the two competing species and allows coexistence in a stable environment (Fig. 3a and 4g). However, if the mean temperature increases (and becomes closer to the optimum of species 1), species coexistence only occurs when variation is large (Fig. 4f). Furthermore, if the mean temperature increases further, even greater environmental variation will not generate species coexistence. In other words, when mean temperature deviates from the intermediate temperature that is non-optimal for both of the competing species and approaches the optimum of either species, the relationship between environmental variation and species coexistence may shift from coexistence-exclusion-coexistence (Fig. 4g-i) to one that promotes coexistence (Fig. 4d-f) to one that favor coexistence but has relatively weaker influence (Fig. 4a-c).