9
Question
Assertion (A): Five closely related species of warblers living on the same tree were able to avoid competition and co-exist.
Reason (R): They could avoid competition by choosing different foraging patterns.
Assertion (A): Five closely related species of warblers living on the same tree were able to avoid competition and co-exist.
Reason (R): They could avoid competition by choosing different foraging patterns.
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Solution
The correct option is A Both the assertion and reason are true and reason is the correct explanation of assertion
When more than one species competes for the same resource in nature, they might evolve mechanisms such as ‘resource partitioning’ that promote coexistence and reduce the intensity of competition.
MacArthur studied five closely related species of insectivorous birds called warblers - Cape May, Yellow-rumped, Black-throated, Blackburnian, and Bay-breasted. They lived on the same coniferous trees and appeared to be an exclusion to the competitive exclusion principle which states that two species with essentially the same niche cannot coexist because one will always out-compete and displace the other.
He divided the trees into different zones and recorded feeding positions of the different warblers within each of them.
One species of bird was found to feed more among the abundant new needles and buds of the tip of a branch, between 20 and 30 feet from the top of the tree.
A different species fed mostly among dead needles at the same height but in the middle zone of a branch.
A third warbler species feeds on the bare, lichen-covered base of the branch. Similarly, various different positions were distinguished.
MacArthur also observed that each warbler species divided its time differently among various parts of the tree.
MacArthur also recorded details of the warblers' foraging habits and discovered that they differed too. They are partitioning a limiting resource -- their supply of insects and is hence called ‘resource partitioning’. It allows them to coexist despite competition.
Hence, both the assertion and reason are true and reason is the correct explanation of assertion.
When more than one species competes for the same resource in nature, they might evolve mechanisms such as ‘resource partitioning’ that promote coexistence and reduce the intensity of competition.
MacArthur studied five closely related species of insectivorous birds called warblers - Cape May, Yellow-rumped, Black-throated, Blackburnian, and Bay-breasted. They lived on the same coniferous trees and appeared to be an exclusion to the competitive exclusion principle which states that two species with essentially the same niche cannot coexist because one will always out-compete and displace the other.
He divided the trees into different zones and recorded feeding positions of the different warblers within each of them.
One species of bird was found to feed more among the abundant new needles and buds of the tip of a branch, between 20 and 30 feet from the top of the tree.
A different species fed mostly among dead needles at the same height but in the middle zone of a branch.
A third warbler species feeds on the bare, lichen-covered base of the branch. Similarly, various different positions were distinguished.
MacArthur also observed that each warbler species divided its time differently among various parts of the tree.
MacArthur also recorded details of the warblers' foraging habits and discovered that they differed too. They are partitioning a limiting resource -- their supply of insects and is hence called ‘resource partitioning’. It allows them to coexist despite competition.
Hence, both the assertion and reason are true and reason is the correct explanation of assertion.
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