Question

In Colorado subalpine meadows, nonnative dandelions co-occur with a native flower, the larkspur. Bumblebees visit both species, creating the potential for interactions between the two species with respect to pollination. In a recent study, researchers selected 16 plots containing both species; all dandelions were removed from eight plots; the remaining eight control plots were left undisturbed. The control plots yielded significantly more larkspur seeds than the dandelion-free plots, leading the researchers to conclude that the presence of dandelions facilitates pollination (and hence seed production) in the native specifies by attracting more pollinators to the mixed plots. Which of the following, if true, most seriously undermines the researchers’ reasoning?
(A) Bumblebees preferentially visit dandelions over larkspurs in mixed plots.
(B) In mixed plots, pollinators can transfer pollen from one species to another to augment seed production.
(C) If left unchecked, nonnative species like dandelions quickly crowd out native species.
(D) Seed germination is a more reliable measure of a species’ fitness than seed production.
(E) Soil disturbances can result in fewer blooms, and hence lower seed production.

Answer 1

Answer:

(E) Soil disturbances can result in fewer blooms, and hence lower seed production.

Explanation:

According to the experiment, the eight control plots were left undisturbed, that is, their soil was not exposed to any disturbance. On the other hand, the soil of the experimental plots was disturbed during the removal of dandelion species. This disturbance might have resulted in reduced flowering in the experimental plots due to many reasons such as removal of fertile topsoil.

The reduced flowering in these plots might have caused lower seed set. The control groups had undisturbed soil which in turn favored more flowering and seed production than in the experimental groups.