Q.11 Given below are two statements:
Statement I :Speciation can occur rapidly or slowly.
Statement II: Speciation can take place with geographic separation only.
In the light of the above statements, choose the most appropriate answer from the options given below :
1. Both Statement I and Statement II are correct
2. Both Statement I and Statement II are incorrect
3. Statement I is correct but Statement II is incorrect
4. Statement I is incorrect but Statement II is correct
Speciation Statements: I True, II False (No Geographic Barrier Needed)
Speciation—the formation of new species—varies in tempo and doesn’t always need physical barriers. The correct answer is 3. Statement I is correct but Statement II is incorrect.
Statement I accurately notes variable rates, from gradual Darwinian change to rapid polyploid events. Statement II wrongly limits speciation to allopatric (geography-based) modes, ignoring sympatric alternatives.
Statement I: Rapid or Slow Speciation
Speciation rates span generations to millennia. Gradual phyletic change accumulates mutations over deep time, while punctuated equilibrium shows stasis punctuated by rapid bursts during isolation.
Polyploidy in plants (e.g., wheat) creates instant reproductive isolation—one generation yields a new species. Fossil records confirm both tempos exist.
Statement II: Geographic Separation Not Required
Allopatric speciation uses barriers like rivers or mountains to halt gene flow, fostering divergence (e.g., Galápagos finches). However, sympatric speciation occurs within uniform habitats via polyploidy, habitat niches, or sexual selection—no geography needed.
Paripatric (edge populations) and peripatric modes blend elements, but sympatric proves Statement II false. Examples include cichlid fishes speciating by color preference in one lake.
All MCQ Options Evaluated
| Option | Evaluation | Correct? |
|---|---|---|
| 1 | Both true | No—ignores sympatric speciation |
| 2 | Both false | No—rates vary (I true) |
| 3 | I true, II false | Yes—variable tempo, multiple modes |
| 4 | I false, II true | No—rates proven variable |
Types of Speciation Summary
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Allopatric: Geographic isolation primary.
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Sympatric: Same area, behavioral/genetic barriers.
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Parapatric/Peripatric: Partial/edge separation.
These mechanisms highlight evolution’s flexibility beyond geography.
Correct Answer: 3. Statement I is correct but Statement II is incorrect
