I1N1T1R1O1G2R1E1S1S1I1O1N1S1
15 points
INTROGRESSIONS is validvalid
INTROGRESSION,
INTROGRESSION, the modification of species by the backcrossing of the hybrids with the parent species
INTROGRESSION,
INTROGRESSION, the modification of species by the backcrossing of the hybrids with the parent species