In some rocky intertidal habitats, the barnacle Chthamalus can survive across the same depths as can the barnacle Balanus. However, where the two species occur together, Chthamalus adults are found only in the more stressful upper portions of the habitat where they are more able than Balanus to resist desiccation. This is an example of:
A)a mutualistic symbiosis.
B)intraspecific competition reducing the size of Chthamalus' fundamental niche to a smaller realized niche.
C)mutualism reducing the size of Balanus' realized niche to a smaller fundamental niche.
D)competitive exclusion reducing the size of Chthamalus' fundamental niche to a smaller realized niche.
E)competitive exclusion expanding the size of Balanus' realized niche to a larger fundamental niche.

Question

Quizplus · Accepted Answer

The presence of Balanus in the lower portions of the habitat, where there is less desiccation stress, suggests that Balanus adults are more tolerant of this stress than Chthamalus. Therefore, Chthamalus adults are limited to the upper portions of the habitat due to competition with Balanus adults for space and resources. This represents competitive exclusion, where one species (Chthamalus) has a smaller realized niche due to competition with another species (Balanus), resulting in a reduction of its fundamental niche.

In Some Rocky Intertidal Habitats, the Barnacle Chthamalus Can Survive