Q.20 Competition between two populations in an ecosystem is
(A) beneficial (+) to both the populations
(B) deleterious (˗) to both the populations
(C) beneficial (+) to one population, but deleterious (˗) to the other population
(D) beneficial (+) to one population, but no effect (0) on the other population
Competition between two populations in an ecosystem is deleterious (-) to both populations, making option (B) correct.
Option Analysis
Option (A) claims competition benefits both populations (+/+). This describes mutualism, not competition, where species like bees and flowers aid each other.
Option (B) states competition harms both (-/-). In interspecific competition, species vie for limited resources like food or space, reducing survival and reproduction for both if the rival were absent.
Option (C) suggests benefit to one and harm to the other (+/-). This fits predation or parasitism, such as a lion (+ ) harming a zebra (-).
Option (D) indicates benefit to one with no effect on the other (+/0). This matches commensalism, like barnacles on whales benefiting without harming the host.
Competition between two populations in an ecosystem occurs when species compete for scarce resources, proving deleterious (-) to both as per standard ecology principles. This interaction shapes community dynamics, often leading to resource partitioning or competitive exclusion.
Key Effects
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Both populations experience reduced fitness, growth, and reproduction due to shared resource demands.
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Outcomes include one species dominating (exclusion) or niche differentiation for coexistence.
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Intraspecific competition (within species) typically exceeds interspecific for stable ecosystems.
Real-World Examples
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Darwin’s finches compete for seeds; beak sizes evolve to partition resources.
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Invasive species like purple loosestrife outcompete natives, altering habitats.
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Foxes and coyotes vie for small mammals, impacting population sizes.
This concept is vital for CSIR NET Life Sciences, testing population interactions alongside mutualism (+/+), predation (+/-), and commensalism (+/0).
