Figure 6: Cumulative degree distributions for OTUs (black dots, bottom and left axes) and sponges (red dots, top and right axes).

Black dots correspond to the number of different host species (k) that contain a given OTU, represented as the cumulative probability of finding an OTU in the network with k or less-associated hosts (Pc(k)). Red dots correspond to the number of different OTUs (k) found in a given host species, represented as the cumulative probability of finding a sponge host with k or less-associated OTUs (Pc(k)). The OTU degree distribution followed a truncated power-law Pc(k)=k^−0.32 × e^−(k/7.44), while the sponge degree distribution followed an exponential given by Pc(k)=e^−(k/1,849). Blue and orange dots correspond to random degree distributions for OTUs and sponges, respectively, where the number of nodes and links from the empirical distribution is kept constant.