Ques. 1AIPMT 2004
What is a keystone species ?
- A dominant species that constitutes a large proportion of the biomass and which affects many other species
- A species which makes up only a small proportion of the total biomass of a community, yet has a huge impact on the community's organization and survival
- A common species that has plenty of biomass, yet has a fairly low impact on the community's organization
- A rare species that has minimal impact on the biomass and on other species in the community
Answer
(2) A species which makes up only a small proportion of the total biomass of a community, yet has a huge impact on the community's organization and survival
Solution
A keystone species is a species whose effect on the community is very large compared with its abundance or biomass.
⇒ Its removal changes the structure and survival of the whole community (e.g. fig trees in tropical forests, sea star Pisaster in rocky intertidal communities).
∴ It forms only a small part of the total biomass but has a huge impact on the community's organisation.
Answer: (2)