Female nest defense in a coral-reef fish, Dascyllus albisella, with uniparental male care

Intraspecific variation in the patterns of parental care has been observed in a variety of animals; however, the possibility of parental care by a non-caregiving parent of uniparental species has not been thoroughly explored. In the coral-reef damselfish, Dascyllus albisella, only males normally exhibit parental care. In this study, we examined the response of females of this species to egg predators after experimental male removal and an elevated level of egg predation, at two small patch reefs (reefs 1 and 2) in Hawaii. We tested theoretical expectations that a nest was defended only by females which had spawned in the nest, and that larger females had a higher likelihood of defense than smaller females. A nest was defended against egg predators more frequently by females that had spawned in that nest than would be expected by chance. Not all females that had spawned in a given nest participated in defense. There was a positive association between female body length and the likelihood of defense at reef 2, but not at reef 1. Within a set of females that had spawned in the same nest during the same nesting cycle, defending females had larger body lengths than non-defending females at reef 2 but not at reef 1. Lack of association between female size and likelihood of defense at reef 1 was unexpected, but may correlate with the smaller average female size and smaller size differences among females on that reef.