Correct Option (1)
: Keystone species
Keystone species are those whose presence and role within an ecosystem are disproportionately important relative to their abundance. Their removal can lead to significant changes in ecosystem structure and function, often resulting in a cascade of effects that impact numerous other species and the overall health of the community. Examples include predators that control herbivore populations, or species that create habitats for others.
Incorrect Options:
Allopatric species refer to species that have evolved in geographical isolation from each other. This concept relates to speciation mechanisms rather than the ecological role of a species within a community.
Sympatric species are species that have evolved from a common ancestral species while inhabiting the same geographical area. Similar to allopatric species, this term describes a mode of speciation and not the ecological importance of a species in maintaining community structure.
Threatened species are those that are likely to become endangered in the near future throughout all or a significant portion of their range. This classification pertains to conservation status based on population decline and risk of extinction, not their ecological role in supporting other species within a community.