Q.87 Which one of the following is an example of sympatric speciation?
(A) Origin of new species among wasps that pollinate figs
(B) Emergence of a new species among finches that migrated to an island and thus isolated from
their ancestors
(C) Evolution of birds’ and bats’ wings
(D) Speciation of squirrels separated by a wide river
Fig-pollinating wasps exemplify sympatric speciation through host-specific mating and pollinator specialization within the same geographic range.
The correct answer is (A).
Sympatric Speciation Defined
Sympatric speciation occurs without physical geographic barriers—populations diverge in the same area via ecological, behavioral, or chromosomal mechanisms like polyploidy or habitat micro-niches. Reproductive isolation arises from mate choice, temporal shifts, or resource partitioning.
Option Breakdown
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(A) Origin of new species among wasps that pollinate figs: Correct—fig wasps (Agaonidae) speciate sympatrically; each fig species hosts unique wasp lineages that mate inside syconia, preventing interbreeding despite shared habitats. Classic example via host-shift isolation.
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(B) Finches migrated to island, isolated from ancestors: Wrong—allopatric speciation (geographic isolation via dispersal to new island, like Darwin’s Galápagos finches).
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(C) Evolution of birds’ and bats’ wings: Wrong—convergent evolution (analogous structures), not speciation.
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(D) Squirrels separated by wide river: Wrong—allopatric (vicariance—river barrier splits population, e.g., Grand Canyon squirrels).
Introduction to Sympatric Speciation Fig Wasps
Sympatric speciation fig wasps showcase speciation without barriers—each fig species traps specific pollinator wasps that mate inside fruits, creating reproductive isolation in shared habitats. GATE Life Sciences classic: contrasts allopatric examples like island finches.
Fig Wasp Mechanism
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Mutualism drives divergence: Wasps enter fig ostiole → pollinate → lay eggs → offspring inherit fig preference.
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No gene flow: Different fig species = different wasp lineages despite overlap.
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Evidence: Molecular phylogenies match fig-wasp coevolution.
Speciation Type Comparison
| Option | Speciation Mode | Reason |
|---|---|---|
| (A) Fig wasps | Sympatric | Host-specific mating, same range |
| (B) Island finches | Allopatric | Migration + isolation |
| (C) Wings | Convergence | No speciation |
| (D) River squirrels | Allopatric | Physical barrier |
GATE Strategy
Sympatric speciation fig wasps = no geographic separation + reproductive isolation. PYQs test: same area ≠ allopatric. Memorize apple maggot flies, cichlids too. Answer: (A).
