Resource depletion and colonization: A comparison between parthenogenetic and sexual Collembola species

Sexual reproduction is the common mode of reproduction in Collembola but several species reproduce by parthenogenesis. Both reproductive modes have advantages and disadvantages. Usually, under resource-limited conditions sexual species are dominant, whereas parthenogenetic species prevail in stable habitats. In order to investigate if sexual and parthenogenetic Collembola species are affected differently by environmental conditions we established two experiments. In the first experiment laboratory microcosms with declining resources were established to investigate the effect of resource depletion on the density of sexual and parthenogenetic Collembola species. For the second experiment, microcosms were defaunated by heat and inoculated with fresh soil or litter material to investigate the recolonization of defaunated soil and titter by sexual and parthenogenetic species. We hypothesized that parthenogenetic species are more sensitive to resource depletion compared to sexual species, and that they will colonize available habitats faster due to their faster mode of reproduction. Contrary to our first hypothesis, parthenogenetic and sexual Collembola species were similarly affected by resource depletion. In agreement with our second hypothesis, the proportion of parthenogenetic species increased with time when free habitats and plenty of resources were available, indicating that parthenogenetic species in fact are faster colonizers. (C) 2008 Elsevier GmbH. All rights reserved.