species_25 <-> species_10
species_10 + species_11 <-> species_12 + species_14
species_14 <-> species_15
species_11 + species_15 <-> species_12 + species_16
species_16 <-> species_17 + species_18
species_17 <-> species_18
species_18 + species_19 <-> species_20 + species_21
species_17 + species_20 <-> species_19 + species_22
species_9 -> species_8
species_1 -> species_26
species_12 + species_21 <-> species_11 + species_23
species_2 + species_4 <-> species_1 + species_3
species_3 -> species_2
species_12 + species_22 <-> species_11 + species_24
species_7 <-> species_5
species_5 <-> species_4
species_3 + species_6 <-> 2*species_2
species_11 + species_13 <-> 2*species_12
species_23 <-> species_7
species_22 + species_8 <-> species_17 + species_9
species_24 <-> species_27