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GATE 2024 BT Q.43: solution and answer

GATE 2024 · BTQ.43 · 2 marks · MCQ

The evolution of wings in bats and insects is an example of ________ evolution.

  1. (A)

    convergent

  2. (B)

    divergent

  3. (C)

    neutral

  4. (D)

    parallel

See the question in the paper
GATE 2024 BT question 43Tap to open full size

Answer and solution

ANSWER

The evolution of wings in bats and insects is convergent evolution (option A) — two evolutionarily unrelated lineages independently evolved analogous flight structures from different anatomical origins in response to similar functional (locomotor) pressures.

Official answer: ASource: Official answer key, GATE 2024 BT (IISc Bengaluru)

  1. Bats (phylum Chordata, class Mammalia) and insects (phylum Arthropoda) belong to lineages that diverged long before either group evolved flight; they share no winged common ancestor.

  2. Bat wings are modified tetrapod forelimbs, homologous to the forelimbs of other vertebrates; insect wings develop as outgrowths of the body wall/exoskeleton (cuticle) — a completely different anatomical and developmental origin.

  3. Despite this different origin, both structures serve the same function (powered flight) and are superficially similar in role — this is the definition of analogous structures.

  4. Convergent evolution is defined as unrelated or distantly related organisms independently evolving similar (analogous) traits/structures to adapt to similar functional demands — exactly the bat/insect wing case. Hence (A) convergent is correct.

  5. (B) Divergent evolution describes homologous structures in related lineages evolving into different forms/functions (e.g., the vertebrate forelimb becoming an arm, flipper, or wing) — the reverse of what is described here, so (B) is wrong.

  6. (C) Neutral evolution refers to changes fixed by genetic drift with no adaptive significance; it is irrelevant to the clearly adaptive, function-driven similarity of wings, so (C) is wrong.

  7. (D) Parallel evolution involves related lineages with a similar ancestral starting point independently evolving similar traits under similar pressures; bats and insects are not closely related and did not share a similar pre-wing ancestral structure, so (D) is a common distractor but is not correct here.

KEY IDEA

Convergent evolution = unrelated/distantly related lineages independently evolving analogous (not homologous) structures under similar selective pressure — the hallmark being different developmental/anatomical origin but similar function. Bat wings (modified tetrapod forelimb) and insect wings (exoskeletal/cuticular outgrowth) are the classic textbook pair illustrating exactly this.

WATCH OUT FOR

Confusing convergent evolution with parallel evolution: parallel evolution requires related lineages that started from a similar ancestral structure/genetic background and then evolved similar traits independently under similar pressures, whereas convergent evolution involves distantly related lineages with fundamentally different starting structures (homology absent) converging on a similar function. Since bats (chordates) and insects (arthropods) share no winged common ancestor and their wings arise from entirely different tissues, this is convergence, not parallelism — a distinction students often blur.

From the GATE 2024 BT paper. Every question of this paper · Download the full paper · All 11 Population & evolution questions, with notes

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