genetree.tree
0
-1
1
5 9
species1 1 S1
species2 1 S2
species3 1 S3
species4 1 S4
species5 1 S5
species6 1 S6
species7 1 S7
species8 1 S8
species9 1 S9
4 
(((species8,((species9,(species4,(species3,(species2, species1)))), species7)),species5),species6);
3
species8 species1 species3
