Wing shape variation associated with mimicry in butterflies

Area of Science:

• Evolutionary Biology
• Ecology
• Genetics

Background:

• Mimetic resemblance in unpalatable butterflies, particularly wing color patterns, has been extensively studied.
• Heliconius numata butterflies exhibit discrete color-pattern morphs that mimic distantly related Melinaea species.

Purpose of the Study:

• To investigate adaptive convergence in butterfly wing shape, beyond color patterns.
• To determine if wing shape variation in Heliconius numata is associated with mimicry.

Main Methods:

• Quantitative analysis of forewing dimensions in a cross between H. numata morphs.
• Landmark-based geometric morphometrics and elliptical Fourier outline analysis to characterize shape differences.
• Application of these methods to natural populations and comparison with Melinaea comimics.

Main Results:

• Quantitative differences in forewing shape were identified between two H. numata morphs (f. elegans and f. silvana).
• These shape differences were confirmed in natural populations.
• Wing shape variation between these morphs was paralleled in their Melinaea mimics, despite extensive overlap.

Conclusions:

• Wing shape variation in Heliconius numata is associated with mimetic resemblance.
• Adaptive convergence may extend to wing shape in addition to color patterns.
• The supergene controlling color pattern may also influence wing shape differences.