Previous Year Question
Given below are two statements, one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A): Maximum number of the species of butterflies are found in tropical countries.
Reason (R): Butterflies can not tolerate low temperatures.
Select the correct answer using the codes given below:
Both (A) and (R) are true and (R) is the correct explanation of (A)
Both (A) and (R) are true but (R) is not the correct explanation of (A)
(A) is true but (R) is false
(A) is false but (R) is true
Correct Answer: A
Detailed Solution
Assertion (A) — The maximum number of butterfly species occurs in tropical countries. Butterflies belong to the Order Lepidoptera. Their Species Diversity is generally higher in Tropical Regions. This geographical pattern is known as the Latitudinal Diversity Gradient. Greater solar energy, favourable temperatures, sufficient rainfall, and diverse vegetation provide suitable conditions for butterfly development and reproduction in these regions.
Reason (R) — Butterflies cannot survive at low temperatures. Butterflies are Ectothermic organisms whose body temperatures are influenced by their external environment. They require sufficient warmth for flight and other physiological activities. Cold conditions may restrict their activity, ability to obtain food, and reproduction. Consequently, warm climates are favourable for many butterfly species.
The Life Cycle of Butterflies consists of four stages—Egg, Larva, Pupa, and Adult. Not all butterflies die in cold conditions. Some species survive winter by entering a dormant state called Diapause, during the egg, larval, pupal, or adult stage. For example, several butterfly species inhabit cold alpine environments above approximately 3,000 metres in Yosemite National Park, North America. Their immature stages can survive long winters through dormancy.
Scientific Clarification: Published solutions to UPPSC 2019 accept option (a). However, the statement ‘Butterflies cannot survive at low temperatures’ is a generalization rather than a universal scientific fact. Greater butterfly diversity in tropical regions is associated not only with temperature but also with rainfall, Host Plant Diversity, habitat complexity, and evolutionary history. A scientific study published in 2021 identified historical climate changes and evolutionary processes as important factors underlying the high species richness of tropical butterflies.