Despite the need for most adult fireflies to respond to a clearly sexual and colorful visual signal (bioluminescence) to maximize fitness, their visual system is relatively simple, and does not match the trend for opsin duplication found in other insect groups. Bioluminescent communication in adults is not optimized to be present ancestrally, and was gained two times with six subsequent losses. We also use a phylogenetic estimate of Lampyridae to examine the evolution and ancestral modality of adult courtship communication.We find evidence for only two expressed opsin classes in each of the nine firefly species studied, one in the ultraviolet-sensitive and one in the long-wavelength-sensitive areas of the visible spectrum. We use a transcriptomic approach to sample for and investigate opsin evolution in fireflies. The molecular basis for this communication is relatively simple: one gene family (opsins) controls the detection of the signal, and one gene family (luciferase) controls the production of the signal.

They are the best-known case of a terrestrial organism that communicates through the use bioluminescence. Here, we look at the visual system of fireflies (Coleoptera: Lampyridae), which offer an elegant system in which to study visual evolution as it relates to their behavior and broader ecology. However, within the beetles, very little work on opsins has been conducted. Among insects, opsin copy number variation has been shown to be quite diverse.

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