Mecoptera

Manwaring, Katie F., Whiting, Michael F., Wilcox, Edward & Bybee, Seth M., 2016, A study of common scorpionfly (Mecoptera: Panorpidae) visual systems reveals the expression of a single opsin, Organisms Diversity & Evolution (New York, N. Y.) 16 (1), pp. 201-209 : 203

Mecoptera opsins

There are two studies that represent what is known of mecopteran opsin diversity ( Burkhardt and de la Motte 1972; Taylor et al. 2005). These studies employed electroretinograms and complementary DNA (cDNA) to answer research questions regarding panorpid and boreid visual systems, but neither directly investigated the number of opsin classes and copies the group possesses. Burkhardt and de la Motte (1972) used electrophysiology to measure the spectral sensitivity of P. cognata and found that its maximum spectral sensitivity peak was at 490–520 nm with a beta peak (signal from cis-formation of the chromophore) at 360 nm. Taylor et al. (2005) used degenerate primers to amplify opsins in six species of panorpids and one species of boreid ( Boreus coloradensis ). They found only the LW opsin using degenerate primers from these taxa.

We present the first molecular data isolated from transcriptomes of mecopteran eye tissue for three taxa ( Panorpa acuminata ( Byers 1993) , P. nebulosa , and Boreus coloradensis ( Byers 1955)) . Our main objective is to determine if panorpids are capable of polychromatic vision or if there is evidence that they are monochromatic ( Burkhardt and de la Motte 1972). Transcriptomes (RNA-seq) of insect eye tissues are useful for identifying opsins (e.g., Bybee et al. 2012). Once generated, the transcriptome can be used to discover the class and copy-number variation of expressed opsins in the eye tissue as well as obtain the entire exonic sequence of each opsin copy.

It is possible that panorpids and boreids may express opsins from the three classes of opsins (UV, Blue, and LW), similar to other insect orders, but at levels that are not detectable physiologically. If this is the case, the biological relevance of the UV and B opsin copies to the Mecoptera visual system is completely unclear. We included Boreidae on the rationale that (1) they represent a primitive mecopteran lineage that is consistently recovered at the base of Mecoptera ( Whiting 2002; Misof et al. 2000); (2) boreids appear to be much less visually oriented than panorpids in nature. They are apterous, are non-predatory, and have a uniform, metallic-black coloration. While good at detecting movement, boreids seem to have little B need^ to distinguish colors like panorpids; and (3) for comparison purposes with Taylor et al. (2005).