Reproductive Behaviour and Ecology of Symphodus (Crenilabrus) Ocellatus, a European Wrasse With Four Types of Male Behaviour

Abstract The temperate, gonochoristic wrasse Symphodus ocellatus was studied in the field (Corsica). The largest males defend an area within which an average of 3-5 successive nests are built from algae. These brightly coloured, paternal, territorial males (T-males) spend between one and two thirds of their time during the 10-day nest cycle building the nest and fanning. They eat very little at this time, although they consume eggs and invertebrates in the nest, including egg predators. T-males occasionally take over neighbouring nests. Nest acquisition has two functions: nourishment (2/3 of all take-overs) and reproduction (1/3). T-males practising the latter save over 1/3 of the time of a complete nest cycle. Most take-over males that acquire nests solely for nourishment fan it, as do their reproducing counterparts. Small males with inconspicuous female colouration roam about and try to fertilize eggs parasitically when females spawn in T-males' nests. There are usually several of these "sneakers" around successful nests. Medium sized males (smaller than T-males and differently coloured) also cuckold T-males, but often display submissively to them. They participate in nest defence against conspecifics and in interactions with females, with an average effort that even exceeds that of the nest owners. Males displaying this "satellite behaviour" feed much less than sneakers and remain at one nest during most of its spawning phase. They are more tolerated by T-males than are sneakers, although they are on average only half as far away from the nest and thus much more frequently encountered by the T-male. The proportion of time a male spends as a satellite depends on its size. Usually only the largest accessory male at a nest behaves in this manner, though smaller males occasionally perform elements of satellite behaviour. Satellites never participate in nest building, courtship, direct broodcare or interspecific defence, nor do they take over abandoned nests. A fourth type of male, similar in size and appearance to sneakers and satellites, refrains from reproduction in a specific year. These males are perhaps future T-males. All females seem to participate in reproduction every year. They spawn repeatedly in the same nest over one day, but often change nests and T-males on successive days. Male tactics are roughly determined by size, but there are still choices to be made, such as when to give up a nest which has little spawning success, whether to build a nest or to attempt a take-over, or when to reproduce and whether to adopt the sneaker or satellite roles. The simultaneous occurrence of T-males, satellites and sneakers within a species is compared to a few other examples of diverse taxa.