Species-Specific Utilization of Food Sources by Sympatric Woodlice (Isopoda: Oniscidea)

• Published in: The Journal of animal ecology 2000-11, Vol.69 (6), p.1071-1082
• Main Authors: Zimmer, Martin, Topp, Werner
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Human ecology; Isopoda; Microbiota; Mortality; Oniscidae; Oniscus asellus; Plant litter; Population dynamics; Population size; Porcellio scaber; Porcellionidae; Protozoa. Invertebrata; Sympatric species; Tannins; Young animals
• ISSN: 0021-8790; 1365-2656
• DOI: 10.1046/j.1365-2656.2000.00463.x

1. In long-term laboratory studies, the influence of different food materials on parameters of population dynamics was compared in the sympatric woodlice, Porcellio scaber and Oniscus asellus, as a measure of interspecific differences in the utilization of food. 2. Freshly fallen leaf litter of different tree species had been acidified and microbially inoculated prior to the experiments. By analysing the influence of pH level, density and activity of litter-colonizing microbiota and several physico-chemical characteristics of the leaf litter, we obtained information on those factors that determine food quality. 3. The studied species responded similarly to different leaf litter species in that both P. scaber and O. asellus performed better on litter with low C:N ratio. Overall, both isopod species reproduced more successfully on litter with higher pH levels, containing half the levels of tannins and other phenolics. 4. Interspecific differences were obvious with respect to the significance of litter-colonizing microbiota, and the dependence of juveniles on particular food parameters. While the performance of adult P. scaber was influenced by both litter-colonizing microbiota and physico-chemical characteristics of the leaf litter, adult O. asellus were influenced by leaf litter characteristics, but not by litter-colonizing microbiota. Juvenile mortality was affected by the tested food parameters in O. asellus, but not in P. scaber. Growth rates of juveniles of both species were influenced by physico-chemical characteristics of the leaf litter. Additionally, leaf litter microbiota had a significant influence on growth rates in juvenile P. scaber, but not in juvenile O. asellus. 5 Reasons for, and consequences of, similarities and differences between the observed sympatric species, and intraspecific differences between ontogenetic stages, are important aspects of soil ecology and may help explain the sympatric coexistence of two species belonging to the same guild of saprophagous soil animals.