What concept is Robert Paine associated with in ecological studies?

Robert Paine is primarily associated with the concept of keystone species and their significant role in shaping community structure within ecosystems. He introduced this idea through his pioneering work in the 1960s, where he conducted field experiments that demonstrated how certain species have a disproportionately large impact on their environment compared to their abundance or biomass.

Paine's studies, particularly on the sea star (Pisaster ochraceus), illustrated that the removal of this keystone predator led to a dramatic shift in the community structure, resulting in decreased diversity and the overpopulation of certain mollusks. This showcased how the presence or absence of a single species can influence the composition and stability of an entire ecological community. By understanding the role of keystone species, ecologists can better grasp the complexities of interactions within ecosystems and the importance of biodiversity in maintaining ecological balance.