Assertion : The community of an ecotone commonly contains the organisms of each of the overlapping communities and in addition the organisms which are restricted to the ecotone.
Reason : The tendency for increased variety and density at community junctions is known as the edge effect.

Answer

B

Explanation

An ecotone is a transition zone between two or more diverse communities as, for example, between forest and grassland. It is a junction zone which may have considerable linear extent but is narrower than the adjoining community areas themselves. The ecotonal community commonly contains many of the organisms of each of the overlapping communities and in addition, organisms which are characteristic of and often restricted to the ecotone. Often, both the number of species and the population density of some of the species are greater in the ecotone than in the communities flanking it. The tendency for increased variety and density at community junctions is known as the edge effect.