Diversity in interspecific interactions between a nest-associating species, Pungtungia herzi, and multiple host species

Nest association in fishes affects the reproductive success of the host to varying degrees, from complete failure of the host’s reproduction to fitness advantages. Such varying impacts of nest association are considered to result from both the associate’s behavior and the characteristics of the host’s reproduction. To investigate the relationship between the impact of nest associate and host/associate ecology as well as evolutionary strategies involving nest association, we compared reproductive strategies and success between an associate East Asian minnow, Pungtungia herzi , and two host fishes (a goby, Odontobutis obscura , and a catfish, Pseudobagrus nudiceps ) that have different reproductive ecologies. The associate frequently spawned around the days on which both hosts spawned, and gained a fitness advantage through continuous egg protection. Spawning by the associate had a negative effect on the survival of O . obscura eggs. Male O . obscura tended to abandon their nest when it was parasitized during the pre-spawning period. This is likely a tactic to alleviate the costs of brood parasitism. In contrast, survival of P . nudiceps eggs was consistently high in all nests, regardless of the intensity of associate’s spawning, and P . nudiceps young fed on cyprinid offspring (most probably the associate’s eggs/young) in the nest. Both P. nudiceps and P. herzi populations likely gain fitness benefits from their relationship. When comparing these two hosts with another known host, the freshwater perch Coreoperca kawamebari , the observed differences in the impact of nest association to the associate species likely correspond to differences in the spatial reproductive resources used by the respective hosts.