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Which of the following phenomena might have influenced the evolution of organisms? 1. Continental drift 2. Glacial cycles Select the correct answer using the code given below.
Explanation
Both continental drift and glacial cycles have influenced the evolution of organisms.
Continental drift began around 200 million years ago when Pangaea split into Laurasia and Gondwanaland, which subsequently broke into smaller continents that exist today.[1] This breakup separated populations of organisms across different landmasses, leading to geographic isolation. When species are isolated on different continents, they evolve independently in response to different environmental conditions, resulting in divergent evolution and speciation.
During the last one million years there had been alternating glacial and inter-glacial episodes.[2] These glacial cycles created dramatic environmental changesâice ages brought harsh, cold conditions while inter-glacial periods were warmer. Such climatic variations acted as selective pressures, forcing organisms to adapt or face extinction. Species that could adapt to changing temperatures, food availability, and habitats survived and evolved, while others perished.
Both phenomenaâcontinental drift causing geographic isolation and glacial cycles causing climatic variationsâserved as major evolutionary drivers by creating diverse environmental pressures that shaped the characteristics of organisms over geological time.
Sources- [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 3: Interior of the Earth > CONTINENTAL DRIFT > p. 27
- [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 7: Climate Change > IntroductIon. > p. 8
PROVENANCE & STUDY PATTERN
Guest previewThis is a classic 'Interdisciplinary Bridge' question. It tests if you can connect Physical Geography (NCERT Class XI) with Basic Biology. It validates that you shouldn't study Geography in a silo; you must understand the *consequences* of geological events (Drift, Ice Ages) on the biosphere.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Explicitly states that much evidence for continental drift came from distribution of flora and fauna â linking continental movement to organismal distribution.
- Implies that changes in continental positions affected where species lived, a key mechanism for evolutionary change (vicariance, isolation).
- Describes the breakup of Pangaea into Laurasia and Gondwanaland, a major geographic reorganization that would separate populations.
- Provides the historical-geological context (continental fragmentation) that can drive speciation and divergent evolution.
- Gives timing and the existence of a single supercontinent (Pangaea) and its later breakup (~200 Ma), allowing correlation with major evolutionary events.
- Establishes the large-scale continental movements necessary for long-term biogeographic and evolutionary effects.
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