Interactions among bacterial-feeding nematode species at different levels of food availability
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ORIGINAL PAPER
Interactions among bacterial-feeding nematode species at diVerent levels of food availability Giovanni A. P. dos Santos · SoWe Derycke · Verônica G. F. Genevois · Luana C. B. B. Coelho · Maria T. S. Correia · Tom Moens
Received: 28 June 2008 / Accepted: 8 December 2008 / Published online: 24 December 2008 © Springer-Verlag 2008
Abstract Accurate prediction of the biodiversity–ecosystem functioning relationship requires adequate understanding of the interactions among species in a community. EVects of species diversity on ecosystem functioning are usually considered more pronounced with increasing functional dissimilarity, although species within functional groups may also perform non-identical functions and interact with each other. Here we present results of a laboratory experimental study aimed at elucidating whether interspeciWc interactions among species within a single nematode trophic group, bacterivores, (1) aVect population development and community structure, and (2) depend on food availability. We studied the population growth of Rhabditis (Pellioditis) marina, a rhabditid nematode known to favour very high food densities when in monoculture, and of Diplolaimelloides meyli and D. oschei, congeneric Monhysteridae known to perform better in monocultures at intermediate food availability. Both Diplolaimelloides species showed signiWcantly diVerent patterns of food-density dependence in combination culture compared to monoculture. At very high food availability, the rhabditid nematode facilitated growth of both monhysterid species, probably as a result of down-regulation of bacterial density. At the lowest food availabilities, the presence of even low numbers of
Communicated by S.D. Connell. G. A. P. dos Santos · S. Derycke · T. Moens (&) Marine Biology Lab, Biology Department, Ghent University, Krijgslaan 281/S8, 9000 Ghent, Belgium e-mail: [email protected] V. G. F. Genevois · L. C. B. B. Coelho · M. T. S. Correia Universidade Federal de Pernambuco, Av. professor Moraes Rêgo, s/n, 50.000.000 Recife, Pernambuco, Brazil
monhysterid nematodes lead to exclusion of the rhabditid, which at such low food availability has a very ineYcient food uptake. At intermediate food availabilities, abundances of both Diplolaimelloides species were strongly depressed in the combination culture, as a result of food depletion by the rhabditid, indirect inhibitory interactions between the two congeneric species, or both. The complexity of the species interactions render predictions on the outcome and functional consequences of changes in withintrophic-group diversity highly problematic.
Introduction Accurate prediction of the biodiversity–ecosystem functioning relationship requires that the ecological roles of, and the interactions among the component species in a community be adequately understood (Johnson et al. 1996). The answer to the question whether individual species eVects can simply be summed to obtain an adequate understanding of how the total community will function, largely depends on how these spe
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