The most intense form of competition is that from your own species, nothing else requires exactly the same conditions/ecological niches/resources. The less fit individuals are out competed (dont breed, or die), and the species as a whole is "pulled" in a certain fitness direction that is more optimal.
The reason speciation arises is complex, but its often due to different subgroups of a species exploiting different niches, and thus experiencing differing fitness pulls that eventually give rise to new species.
There are no "intermediate" species because they fit more poorly into either niche occupied by the two other species, and thus are out competed or dont arise in the first place.
The reason speciation arises is complex, but its often due to different subgroups of a species exploiting different niches, and thus experiencing differing fitness pulls that eventually give rise to new species.
There are no "intermediate" species because they fit more poorly into either niche occupied by the two other species, and thus are out competed or dont arise in the first place.