Species are often excluded from habitat in which they could exist perfectly well in the absence of interspecific competition.As an example,Dolly Varden charr can live in the white-spotted charr zone,but only when
A) That zone is highly populated with white-spotted charr.
B) There are no white-spotted charr present.
C) The two species are found together, the water temperature is higher than usual, and Dolly Varden charr become more aggressive to individuals of its own species.
D) None of the above.

Question

Quizplus · Accepted Answer

The statement in the question suggests that Dolly Varden charr can live in the white-spotted charr zone, but are excluded from it. This implies that the exclusion is due to interspecific competition. Therefore, the presence of white-spotted charr is likely to be the reason for the exclusion. Thus, the correct choice is B, which states that Dolly Varden charr can live in the white-spotted charr zone only when there are no white-spotted charr present. Choices A and C are incorrect because they suggest that Dolly Varden charr can coexist with white-spotted charr under certain conditions, which contradicts the premise of the question. Choice D is incorrect as well, as B is the correct answer.

Species Are Often Excluded from Habitat in Which They Could