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Seed dormancy has been considered, almost without exception, as a bet-hedging strategy in a temporally varying environment. However, in this paper we show that seed dormancy can improve the reproductive success of the mother plant when competition between sibling seedlings and adult plants is intense even if the environment is temporally invariable. We allow a cohort of sibling seeds to germinate simultaneously in the same patch and assume a density dependent survival and fecundity of seedlings. In the model, the mother plant is assumed to control the germination behaviour of the seeds, e.g. by enclosing the seeds in coats of different hardiness. When sib competition is intense, a postponed germination of her seeds can increase the reproductive success of the mother plant up to four times, measured in terms of the number of grandchildren. Consequently, our results suggest that postponed germination may function as a mechanism that alters local interactions in viscous plant populations with limited dispersal.

Background Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, but also a common colonizer of the upper respiratory tract. The emergence and spread of antibiotic resistant pneumococcal strains has threatened effective therapy. The long-term effects of measures aiming to limit pneumococcal spread are poorly understood. Computational modeling makes it possible to conduct virtual experiments that are impractical to perform in real life and thereby allows a more full understanding of pneumococcal epidemiology and control efforts. Methods We have developed a contact network model to evaluate the efficacy of interventions aiming to control pneumococcal transmission. Demographic data from Sweden during the mid-2000s were employed. Analyses of the model's parameters were conducted to elucidate key determinants of pneumococcal spread. Also, scenario simulations were performed to assess candidate control measures. Results The model made good predictions of previous findings where a correlation has been found between age and pneumococcal carriage. Of the parameters tested, group size in day-care centers was shown to be one of the most important factors for pneumococcal transmission. Consistent results were generated from the scenario simulations. Conclusion We recommend, based on the model predictions, that strategies to control pneumococcal disease and organism transmission should include reducing the group size in day-care centers.