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Q8:
Describe one example of adaptive radiation.
Solution :
Definition of Adaptive Radiation
Adaptive radiation is an evolutionary process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches. [Per the principles of Evolutionary Biology and Neo-Darwinism].
Example: Darwin’s Finches of the Galápagos Islands
The most archetypal example of adaptive radiation is the diversification of finches observed by Charles Darwin on the Galápagos Archipelago.
Step 1: Geographical Isolation and Founder Effect
Originally, a small population of seed-eating ground finches migrated from the South American mainland to the isolated Galápagos Islands. Because the islands lacked competition from other bird species, the founding population faced an environment with diverse, vacant ecological niches. [By the Principle of Allopatric Speciation].
Step 2: Diversification of Morphological Traits
Over time, these ancestral birds underwent adaptive changes in their beak morphology to exploit different food sources available on various islands. The beak structure became highly specialized based on the diet:
| Finches Type | Ecological Niche | Adaptation (Beak Morphology) |
|---|---|---|
| Ground Finches | Seed consumption | Heavy, strong, blunt beaks for crushing hard seeds. |
| Tree Finches | Insect consumption | Narrow, probing beaks for reaching insects in crevices. |
| Warbler Finches | Dietary specialization | Small, thin beaks for catching delicate prey. |
Step 3: Schematic Visualization of Radiation
Theoretical Justification
This process illustrates Divergent Evolution, where species sharing a common ancestor evolve distinct phenotypic traits to survive in different environmental conditions. The driving force is Natural Selection acting upon the variation of beak size and shape, ensuring maximum fitness within each specialized niche. [Referencing the Hardy-Weinberg equilibrium disruption through selective pressure].
Final Solution: Darwin's Finches represent adaptive radiation, as a single ancestral species migrated to the Galápagos Islands and diverged into multiple specialized species with unique beak morphologies adapted to distinct food sources, effectively occupying diverse ecological niches within the archipelago.
More Questions from Class 12 Biology Evolution EXERCISES
- Q1: Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
- Q1: Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
- Q2: Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
- Q2: Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
- Q3: Attempt giving a clear definition of the term species.
- Q3: Attempt giving a clear definition of the term species.
- Q4: Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)
- Q4: Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)
- Q5: Find out through internet and popular science articles whether animals other than man has self-consciousness.
- Q5: Find out through internet and popular science articles whether animals other than man has self-consciousness.
- Q6: List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
- Q6: List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
- Q7: Practise drawing various animals and plants.
- Q7: Practise drawing various animals and plants.
- Q8: Describe one example of adaptive radiation.
- Q9: Can we call human evolution as adaptive radiation?
- Q9: Can we call human evolution as adaptive radiation?
- Q10: Using various resources such as your school Library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal, say horse.
- Q10: Using various resources such as your school Library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal, say horse.
CBSE Solutions for Class 12 Biology Evolution
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
- Environmental Issues
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