Costs and benefits of a cleaning mutualism

摘要

Mutualisms can be thought of as 'biological markets' in which species trade resources, which can be manipulated by one or both participants. However, temporal and geographical variation in the outcome of mutualisms generates dynamic mosaics of co-evolved interactions, therefore, outcomes of mutualistic interactions may be difficult to interpret with a 'snapshot' quantification of costs and benefits. Cleaning interactions are often used as classic examples of mutualism but assessing benefits to clients has been difficult. In this study we examined the outcome of the interaction between Caribbean cleaning gobies (Elacatinus evelynae) and longfin damselfish (Stegastes diencaeus), by comparing interactions at a number of locations. Previously we have shown that longfin damselfish benefit from cleaning interactions by a significant but small reduction in ectoparasite loads and we suggested that the costs of traveling and seeking cleaners by territorial damselfish may limit the net benefit of cleaning to the client (Cheney & Cote, 2001). Here, we investigate how the relationship alters between geographical locations and in one site, over 3 consecutive years, under varying environmental conditions to elucidate key components affecting cleaning symbioses.