Predation as a factor mediating resource competition among rotifer sibling species

The relevance of predation as a factor mediating the competitive interaction among ecologically very similar species is investigated by experimentally analyzing the effect of the copepod predator Diacyclops bicuspidatus odessanus on three sibling rotifer species belonging to the Brachionus plicatilis species complex. These rotifer species are similar in shape but show notable differences in body size. Predator and prey species co-occur in brackish waterbodies close to the Mediterranean coast of Spain. First, we characterized differential vulnerability of rotifers to predation. A consistent tendency of higher predation rates on smaller prey (i.e., smaller species and younger individuals) was…