Chemosensory receptor copy number evolution is not associated with host-plant specialization in butterflies

Across 87 butterfly species, olfactory receptor (OR) and gustatory receptor (GR) repertoire size is not different between host-plant specialists and generalists.

• Why it matters: Host-plant use is expected to shape insect chemosensory evolution, but it is unclear whether generalists need larger receptor repertoires or whether specialization tracks gene-family size changes.
• What they did: The study annotated OR and GR gene families across 87 butterfly species and used phylogenetic comparative analyses to test links between receptor copy number and specialist versus generalist strategies, including host-plant breadth.
• The result: OR and GR repertoire size showed no association with host-plant family number, and gene-family expansions or contractions were not linked to transitions between generalist and specialist strategies.

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