0 -> species_0
0 -> species_1
species_0 -> 0
species_1 -> species_2
species_1 <-> species_3
0 -> species_4
species_5 -> 0
species_4 -> species_6
species_6 -> 0
0 -> species_7
0 -> species_8
species_9 -> 0
species_8 -> species_9
species_4 + species_8 <-> species_10
species_10 -> species_11
species_11 -> 0
species_10 <-> species_12
species_14 -> 0
species_2 -> 0
species_13 -> 0
0 -> species_5
species_12 -> species_14
species_7 -> 0
species_12 + species_3 <-> species_15
species_0 -> 0
species_5 -> 0
species_7 -> 0
species_8 -> 0
species_4 -> 0
species_9 -> 0
species_6 -> 0
species_11 -> 0
species_10 -> 0
species_14 -> 0
species_1 -> 0
species_2 -> 0
species_3 -> species_13
species_13 -> 0
species_15 -> 0
species_15 -> 0
species_3 -> 0
species_2 -> species_1
species_13 -> species_3
species_6 -> species_4
species_9 -> species_8
species_14 -> species_12
species_12 -> 0
species_11 -> species_10