Different species are likely to have different chromosomes. The hybrid resulting from such a cross will be diploid but its chromosomes won t have their homologs. If it survived up to this point, when it goes to make its own gametes by meiosis, the chromosomes will not have homologs to pair with. They will migrate randomly to different poles of the potential daughter cells, none of which are likely to be viable because they will be missing so many chromosomes. Therefore the hybrid will be sterile, ie, unable to produce viable gametes.
Adaptation is the result of natural selection.
For example, peppered moths with the dark colored trait are more likely to survive in polluted forests than those that are light colored, therefore dark coloration in peppered moths is an adaptation to polluted environments. Opposable thumbs and toes in primates was probably an adaptation for climbing trees, since all tree climbers have them and would probably be much less agile without them, just as lungs are adaptations to air breathing and life in terrestrial environments. Directional natural selection for larger beaks. Night-flowering cacti are more fit under hot summer conditions. All but a are true.