Q.Which of the following is a classic laboratory example of interspecific competition?
(A) Two species of Paramecium (P. aurelia and P. caudatum) grown together, competing for the same limited food
(B) Two male deer fighting for a mate
(C) A lion killing and eating a deer
(D) A tapeworm living inside the human intestine

Interspecific competition, when sustained, drives the weaker competitor toward local extinction (competitive exclusion principle).

When two species compete intensely for an identical limiting resource, one species is usually better adapted and out-competes the other over time. Gause's competitive exclusion principle states that two species competing for the same limiting resource cannot co-exist indefinitely in the same niche — the less efficient competitor is eventually eliminated (locally extinct) unless it shifts its niche. Option (a) Amensalism is a different interaction where one species is harmed and the other is unaffected (e.g., a sapling in the shade of a large tree), not a consequence of competition. Option (c) Symbiosis is a mutually beneficial interaction, the opposite of competition. Optio …

Competition between individuals of the same species for a shared resource is intra-specific struggle.

Darwin classified the struggle for existence into three types: intra-specific struggle (competition among individuals of the same species for limited resources like food, mates, or space), inter-specific struggle (competition between individuals of different species, e.g. predator-prey or two species competing for the same resource), and struggle against nature/environment (competition against unfavourable physical/climatic factors such as drought, cold, or natural calamities). Since two cows (members of the s …