Equivalent cleaning in a juvenile facultative and obligate cleaning wrasse: an insight into the evolution of cleaning in labrids?
Species that exhibit ontogenetic variation in interspecific cleaning behaviours may offer insights into how interspecific cooperation evolves. We investigated the foraging ecology of the yellowtail tubelip wrasse (Diproctacanthus xanthurus), a facultative cleaner as a juvenile and corallivore as an adult, and compared its juvenile ecology with that of juvenile blue-streak cleaner wrasse (Labroides dimidiatus), a closely related and sympatric obligate cleaner. While juveniles of the two species differed in the amount of time they inspected clients, the number of client individuals and species that were cleaned and the proportion that posed did not differ, nor did the number of ectoparasitic isopods in their guts. In contrast, adult yellowtail tubelip wrasse had fewer isopods and more coral mucus in their guts than juveniles. These data support a hypothesized series of events in which juvenile cleaning acts as an evolutionary precursor to obligate cleaning and suggest that the yellowtail tubelip wrasse may present an intermediate between corallivory and cleaning.