Schematic overview of the multiple-species method. (a) Shared-space bicluster seeds are generated by calculating the pairwise correlation of the gene pairs to a randomly selected gene pair. (b) The shared-space multi-species optimization, where orthologous gene pairs are iteratively added or dropped from the bicluster according to the multi-species multi-data score. (c) When completed, shared-space biclusters are separated into their respective species, and further optimized during the elaboration step. During this step the genes from the original shared-space bicluster are prevented from being dropped, as indicated by the boxes surrounding these genes (represented as black circles). OC, orthologous core (the set of actively expressed orthologous genes shared between a group of organisms on which we run our multi-species biclustering).