Which of the following options describes the relationship between a keystone species and its abundance in a biological community?

A. True - A keystone species tends to be the most abundant organism in the community.
B. False - A keystone species is not necessarily the most abundant organism in the community.
C. Not necessarily - The abundance of a keystone species may vary in different biological communities.

B. False. A keystone species is not necessarily the most abundant organism in its biological community but has a significant impact on the community's structure and biodiversity. Removal of a keystone species can lead to drastic ecosystem changes.

Explanation:

The correct answer is B. False - A keystone species is not necessarily the most abundant organism in the community. A keystone species, such as the intertidal sea star Pisaster ochraceus in the northwestern United States, has a disproportionately large effect on its environment relative to its abundance. These species play a critical role in maintaining the structure and biodiversity of their ecological communities. Despite their often low numbers, their impacts can include control over populations of other species and influence on nutrient cycles, like the banded tetra that contributes significant amounts of phosphorus to tropical streams. The removal or loss of a keystone species can lead to dramatic changes in the ecosystem structure and a decrease in biodiversity.