x1 = species_1
x2 = species_2
x3 = species_3
x4 = species_4
x5 = species_5
x6 = species_6
x7 = species_7
x8 = species_8
x9 = species_9
x10 = species_10
x11 = species_11
x12 = species_12
x13 = species_13