Answer :

naturally occurring selective pressures favor new traits.

humans create new environmental conditions.

Answer:

The emergence of the new species of the organisms may take place if the naturally occurring selective pressure encourages the emergence of new traits. The pressure from the surroundings like sudden variation in the climate or temperature or any other thing that develops a pressure on the species to modify phenotypically and genotypically.  

This change will result in the evolution of the species and with the time being the emergence of new species of organisms takes place.