Zoological Institute, University of Basel, Vesalgasse 1, CH-4051 Basel, Switzerland.
Ecology. 2010 Oct;91(10):2975-82. doi: 10.1890/09-2016.1.
Migration is the key process to understand the dynamics and persistence of a metapopulation. Many metapopulation models assume a positive correlation between habitat patch size or stability and the number of emigrants. However, few empirical data exist, and habitat patch size and habitat stability may affect dispersal differently than they affect local persistence. Here, we studied the production of the migration stage (i.e., resting eggs called ephippia) of the cladoceran Daphnia magna in a metapopulation consisting of 530 rock pool habitat patches over 25 years. Earlier, the functioning of this metapopulation was explained with a Levins-type metapopulation model or with a mainland-island metapopulation model, based on local extinction and colonization data or time series data, respectively. We used pool volume, hydroperiod length, and number of desiccation events to calculate per-pool production of ephippia (i.e., migration stages). We estimated that populations in small and ephemeral habitat patches produced more than half of the 250 000 to 1 million ephippia that were produced in the metapopulation as a whole per year between 1982 and 2006. Furthermore, these small populations contributed approximately 90% of the ephippia exposed during desiccation events, while the contribution of the long-lived populations in large pools was minimal. We term this an "inverse mainland-island" type metapopulation and propose that populations in small, ephemeral habitat patches may also be the driving force for metapopulation dynamics in other systems.
迁移是理解复合种群动态和持久性的关键过程。许多复合种群模型假设生境斑块大小或稳定性与迁出者数量之间存在正相关关系。然而，很少有经验数据存在，而且生境斑块大小和生境稳定性可能会以不同于影响局域持久性的方式影响扩散。在这里，我们在一个由 530 个石池生境斑块组成的复合种群中研究了浮游甲壳动物大型溞的迁移阶段（即休眠卵称为卵囊）的产生，该复合种群跨越 25 年。在此之前，根据局域灭绝和定居数据或时间序列数据，分别使用莱文斯型复合种群模型或大陆岛屿复合种群模型来解释该复合种群的功能。我们使用池体积、水期长度和干燥事件次数来计算每个池的卵囊（即迁移阶段）的产量。我们估计，在 1982 年至 2006 年间，小而短暂的生境斑块中的种群每年产生的 25 万至 100 万个卵囊中，超过一半以上来自于整个复合种群。此外，这些小种群在干燥事件中暴露的卵囊约占 90%，而大池中的长寿命种群的贡献则微不足道。我们将这种情况称为“反向大陆岛屿”型复合种群，并提出小而短暂的生境斑块中的种群也可能是其他系统复合种群动态的驱动力。
