Question

According to the Janzen-Connell hypothesis, in order for pathogens or herbivores to contribute to the maintenance of diversity? Select all that apply.

The infections must be avirulent.

The pathogens/herbivores must result in lower seedling mortality close to adult plants of the same species.

The pathogens/herbivores must be host-specific.

The mortality of seedlings due to competition between plants must be less important than mortality due to herbivores/pathogens.

Answer 1

Janzen-Connell hypothesis is well accepted hypothesis for the maintenance of biodiversity of plant species specifically in tropical rain forest. This hypothesis proposes that the pathogens or herbivores, which are specalists natural enemies maintain the biodiversity in plants species by lowering the survivial rate of seedlings or increasing the mortality of the seedlings close to the adult population of same species. Pathogen infection should virulent and hence, the seedlings close to the parent plant will die due to disease, whereas the seedlings away from the parent plant survives. Hence, Option A and B are incorrect.

According to this hypothesis, the pathogens or herbivores are host specific and will not affect or harm other species. As the mortality is high due to predators (Pathogen/ herbivores), the mortality of plants due to competition between them is of least importance. Hence, Options C and D are correct.