Competition killed off all the organisms without traits that were benefitial to them. The organisms in the Galapogos Islands, such as the finches, made adaptions to settle in their new environment.
It can be best explained with the help of Gause's law of competitive exclusion.
It states that no two species can coexist stably which compete for exact same resources.
In such conditions, the species which is inferior to other in terms of adaptations either extinct or evolve towards a different ecological niche.
For example, Galapagos island finches evolved with different shapes and sizes of beaks as an adaptation towards limited resources available such as different types of seeds or food.
The same receptor that responds to norepinephrine also respond to epinephrine, increasing the action of both. Adrenal medulla is NOT affected by the parasympathetic division of the autonomic nervous system (ANS
