The influence of tadpole size on cell-mediated competition between anuran larvae (Bufo calamita and Rana temporaria) in the laboratory

The faeces of tadpoles frequently contain cells that can inhibit the growth of other individuals. We examined the mechanism of such cell-mediated interference competition in interactions between tadpoles of Rana temporaria and Bufo calamita. When R. temporaria and B. calamita tadpoles were exposed to cell-laden faeces from larger R. temporaria tadpoles. growth was inhibited relative to controls. Tadpoles of B. calamita remained susceptible to the inhibitory effects of the cells for longer during development than those of R. temporaria. In the presence of excess food, cell production by both species was related to stage of development. Tadpoles raised with cell-laden faeces from R. temporaria tadpoles produced more cells/tadpole/hour than those raised without competitor faeces, and smaller tadpoles were more inhibited than larger tadpoles.