The inheritance of song and preference in hybrids between Chrysoperla carnea and C. agilis green lacewings

Green lacewings in the Chrysoperla carnea species group are morphologically cryptic but clearly distinguishable via substrate-borne vibrational mating signals that both sexes produce. Two carnea group species, C. carnea and C. agilis, have overlapping ranges and share the same habitats in southern Switzerland. The two species were hybridized in the lab to investigate the patterns of inheritance of songs (i.e. whether hybrids have intermediate songs) and preference for songs (i.e. whether hybrids prefer hybrid songs). Control and F1 hybrid lacewings were given a randomly ordered series of control and F1 hybrid signals. Backcross individuals were given backcross signals in addition to control and F1 hybrid signals. I recorded how many times a lacewing responded to each playback signal. Also, songs of all individuals were measured for song characters such as volley period and frequency structure. Hybrid individuals preferred hybrid signals and control individuals preferred control signals. Backcross individuals preferred backcross signals as well as the control parent’s signal. Measurements of hybrid and backcross signals indicate that the songs share the same underlying genetic system. The results support the preexisting hypothesis that divergent songs played an important role in speciation in the carnea group.