When one species is harmed while the other is unaffected in a population interaction, it indicates -
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Amensalism
Interactions between two species are shown with signs: + for benefit, − for harm and 0 for no effect. The question describes a −/0 interaction: one species is harmed and the other is unaffected.
(1) Commensalism — Incorrect. Commensalism is a +/0 interaction. One species benefits and the other is neither benefited nor harmed, as with an orchid growing on a mango branch.
(2) Mutualism — Incorrect. Mutualism is a +/+ interaction. Both species benefit, as in lichens and mycorrhizae.
(3) Parasitism — Incorrect. Parasitism is a +/− interaction. The parasite benefits and the host is harmed.
(4) Amensalism — Correct. In amensalism, one species is harmed whereas the other is unaffected (−/0).
NCERT Extract:
Population Interactions – “… Assigning a ‘+’ sign for beneficial interaction, ‘-’ sign for detrimental and 0 for neutral interaction, let us look at all the possible outcomes of interspecific interactions (Table11.1). Both the species benefit in mutualism and both lose in competition in their interactions with each other. In both parasitism and predation only one species benefits (parasite and predator, respectively) and the interaction is detrimental to the other species (host and prey, respectively). The interaction where one species is benefitted and the other is neither benefitted nor harmed is called commensalism. In amensalism on the other hand one species is harmed whereas the other is unaffected.”