Question

Keystone species deserve protection because they
a. Are capable of surviving in harsh environmental conditions.
b. Indicate the presence of certain minerals of oil
c. Have become rare due to overexploitation
d. Play an important role in supporting other species

Answer 1

Hint: Keystone species have a larger role in maintaining the ecological balance, affecting several different organisms in an ecosystem. These species feature a disproportionately larger effect on its natural surroundings relative to its abundance.

Complete answer:
A classic keystone species is a predator that prevents a specific herbivorous species from eliminating dominant plant species. If prey numbers per unit area are low, keystone predators can be even less abundant and still be effective. Without keystone species, the ecosystem would completely stop working or would have been completely different from what it is now in today's date.

Keystone species are those species that have a significant influence on the community structure and characteristics. It is generally considered to be of low abundance as compared to dominant species. Removal of such species causes serious damage in the structure and function of the ecosystem community. Thus, these species deserve to have protection. It is a dominant predator removing which allows the increase in the population of prey.

Hence, the correct answer is option (D).

Additional information:
A standard example of keystone species in the context of ecological surroundings is the predator-prey relationship. Tiny predators that consume herbivorous species prevent such herbivore organisms from decimating the plant species within the ecosystem and are considered keystone species. In this condition, despite the less number of predators which is required to maintain a low population of herbivorous species and with the absence of this keystone species, the herbivore population would grow continuously and would consume all of the dominant plant species in the ecosystem. The sea otter is considered a keystone species as they consume sea urchins, thus preventing the destruction of kelp forests which is caused by the sea urchin population.

Note: Other examples of keystone species are; Large mammalian predators, sea star etc. Keystone species influence tropical conditions and provide large ecosystem services which are of vital importance to the economic, social and cultural well-being of humans and animals.