x1 = species_20
x2 = species_21
x3 = species_15
x4 = species_41
x5 = species_28
x6 = species_1
x7 = species_5
x8 = species_2
x9 = species_11
x10 = species_19
x11 = species_7
x12 = species_22
x13 = species_17
x14 = species_42
x15 = species_3
x16 = species_6
x17 = species_9
x18 = species_12
x19 = species_10
x20 = species_27
x21 = species_4
x22 = species_47
x23 = species_8
x24 = species_13
x25 = species_14
x26 = species_16
x27 = species_18
x28 = species_23