For biotic resources can be illuminated by organisms fighting for a limited amount

Answer and Explanation:

An ecosystem is made up of abiotic and biotic factors. The abiotic are non-living while biotic are the flora and fauna. With time, adaptations for specialization and survival of a population may occur due to limited resources. Adaptations bring about variations. In the struggle for existence, individuals with advantageous variations are well adapted to the environment. Those that are poorly adapted perish and do not transmit their characteristics. This is called survival of the fittest.

Natural selection being an important aspect in long-term survival of species involves a mechanism by which beneficial variations are perpetuated while disadvantageous variations are eliminated.