Facultative mimicry: cues for colour change and colour accuracy in a coral reef fish

摘要

Mimetic species evolve colours and body patterns to closely resemble poisonous species and thus avoidpredation (Batesian mimicry), or resemble beneficial or harmless species in order to approach and attackprey (aggressive mimicry). Facultative mimicry, the ability to switch between mimic and non-mimiccolours at will, is uncommon in the animal kingdom, but has been shown in a cephalopod, and recently in amarine fish, the bluestriped fangblenny Plagiotremus rhinorhynchos, an aggressive mimic of the juvenilecleaner fish Labroides dimidiatus. Here we demonstrate for the first time that fangblennies adopted mimiccolours in the presence of juvenile cleaner fish; however, this only occurred in smaller individuals. Fielddata indicated that when juvenile cleaner fish were abundant, the proportion of mimic to non-mimicfangblennies was greater, suggesting that fangblennies adopt their mimic disguise depending on theavailability of cleaner fish. Finally, measurements of spectral reflectance suggest that not only do mimicfangblennies accurately resemble the colour of their cleaner fish models but also mimic other species of fishthat they associate with. This study provides insights into the cues that control this remarkable facultativemimicry system and qualitatively measures its accuracy.