The adaptive significance of spawning synchronization in the Caribbean damselfish Stegastes dorsopunicans (Poey)

Abstract

In the dusky damselfish Stegastes dorsopunicans (Poey) two levels of population reproductive synchrony exist. At one level, there is a broad peak in spawning activity every month between full moon and new moon. Within these lunar peaks of spawning activity, spawning is concentrated on specific days, often flanked by days with no spawning, resulting in spawning peaks within the broader monthly peak. On days of higher spawning activity, more females spawn in a nest that receives eggs, and the average number of eggs a male receives is higher. Larger clutches suffer lower mortality from both complete and partial clutch predation by the father (filial cannibalism). Males are more likely to eat complete clutches when the clutches are small. Fathers also appear to eat a subset of their clutches, but the number of eggs eaten is independent of clutch size, so larger clutches have a lower percentage mortality from partial clutch loss. A separate source of clutch mortality, complete clutch loss to nocturnal predators, affects all clutches equally and does not select for large clutch size and spawning synchrony. The differences in rates of clutch cannibalism between synchronized and nonsynchronized days provides an adaptive explanation for spawning synchrony in this noncolonial fish; female synchrony may have evolved in response to differential egg mortality.