Q.66 In an aquarium two herbivorous species of fish are living together and
feeding on phytoplankton. As per the Gause's principle, one of the
species is to be eliminated in due course of time, but both are surviving
well in the aquarium. Give possible reasons.

Pg 234 class 12

Ans. Competition is a rivalry relationship between two or more organisms. Competition between individuals of the same species (intraspecific) is more acute than the competition between individuals of different species as all the members in an intraspecific competition have the same basic requirements like food, water, light, space, mating, and shelter.

But this is true only when resources are limited. According to Gause's principle, one of the species is to be eliminated.

But studies recently have revealed that species facing intraspecific competition may evolve a mechanism to encourage co-existence rather than exclusion. This can also be done by a method known as 'resource partitioning'