Perfect mimicry between Heliconius butterflies is constrained by genetics and development

Area of Science:

• Evolutionary Biology
• Genetics
• Animal Behavior

Background:

• Müllerian mimicry demonstrates natural selection's adaptive power.
• The precise extent and causes of imperfect mimicry are often unclear.

Purpose of the Study:

• Quantify wing pattern differences in co-mimetic Heliconius butterflies.
• Investigate the role of the WntA gene in imperfect mimicry using gene editing.

Main Methods:

• Comparative analysis of forewing colour patterns in 14 morphs of Heliconius erato and Heliconius melpomene.
• CRISPR/Cas9 gene editing to knock out the WntA gene and observe its effect on wing colour patterns.

Main Results:

• Forewing pattern size is nearly identical between co-mimicking species.
• WntA gene knockout experiments revealed divergent wing boundaries affecting pattern formation differently in each species.
• These boundary differences prevent perfect mimicry.

Conclusions:

• Divergence in gene regulatory networks constrains morphological evolution, even in closely related species.
• Imperfect mimicry in Heliconius butterflies is linked to species-specific WntA gene effects on wing patterning boundaries.