Department of Plant Ecology, University of Tübingen, Germany.
Am Nat. 2010 Oct;176(4):490-500. doi: 10.1086/656271.
Bet hedging is a means to increase fitness in environments that vary unpredictably in space and time. In such environments, models predict a trade-off between the bet-hedging strategies dispersal and dormancy, while the increasing importance of risk reduction with decreasing predictability should lead to an increase in dispersal and dormancy along gradients of environmental predictability. However, so far there has been no experimental study to test these predictions in the field. Here, we used a set of novel field experiments that enabled us to quantify and separate seedling recruitment from three sources: local reproduction, dormancy, and dispersal. The study included the entire plant community from five environments differing considerably in predictability. Evidence for both the existence of a trade-off between dispersal and dormancy within environments and their increased use in unpredictable environments was very weak. The importance of dispersal for population and community dynamics in our system was extremely low relative to dormancy and local reproduction. This indicates that the role of dispersal for buffering environmental variation may be negligible compared with other risk-reducing strategies. Our findings highlight the urgent need for multispecies and multisite experiments in empirical tests of theoretical predictions.
押注避险是一种在空间和时间上不可预测变化的环境中提高适应性的手段。在这种环境下，模型预测了分散和休眠之间的押注避险策略的权衡，而随着可预测性的降低，风险降低的重要性增加，应该会导致随着环境可预测性梯度的增加，分散和休眠的增加。然而，到目前为止，还没有野外实验研究来检验这些预测。在这里，我们使用了一组新的野外实验，使我们能够从三个来源量化和分离幼苗的繁殖：本地繁殖、休眠和分散。这项研究包括来自五个在可预测性上差异很大的环境的整个植物群落。在环境中，分散和休眠之间存在权衡，以及它们在不可预测环境中使用增加的证据非常微弱。在我们的系统中，相对于休眠和本地繁殖，分散对种群和群落动态的重要性极低。这表明，与其他降低风险的策略相比，分散在缓冲环境变化方面的作用可能微不足道。我们的研究结果强调了在理论预测的实证检验中进行多物种和多地点实验的迫切需要。
