To grant to species the special power of producing hybrids, and then to stop their further propagation by different degrees of sterility, not strictly related to the facility of the first union between their parents, seems a strange arrangement.
Espezieari hibridoak sortzeko ahal berezia eman eta, gero, gurasoen lehen gurutzaketaren erraztasunarekin zerikusi hertsirik ez duten antzutasun maila ezberdinez, haien ugalmena gerarazteak, antolakera arraroa dirudi.