Data from: Inferring contemporary dispersal processes in plant metapopulations: comparison of direct and indirect estimates of dispersal for the annual species Crepis sancta

Analyzing population dynamics in changing habitats is a prerequisite for population dynamics forecasting. The recent development of metapopulation modeling allows the estimation of dispersal kernels based on the colonization pattern but the accuracy of these estimates compared with direct estimates of the seed dispersal kernel has rarely been assessed. In this study, we used recent genetic methods based on parentage analysis (spatially explicit mating models) to estimate seed and pollen dispersal kernels as well as seed and pollen immigration in fragmented urban populations of the plant species Crepis sancta with contrasting patch dynamics. Using two independent networks, we documented substantial seed immigration and a highly restricted dispersal kernel. Moreover, immigration heterogeneity among networks was consistent with previously reported metapopulation dynamics, showing that colonization was mainly due to external colonization in the first network (propagule rain) and local colonization in the second network. We concluded that the differences in urban patch dynamics are mainly due to seed immigration heterogeneity, highlighting the importance of external population source in the spatio-temporal dynamics of plants in a fragmented landscape. The results show that indirect and direct methods were qualitatively consistent, providing a proper interpretation of indirect estimates. This study provides attempts to link genetic and demographic methods and show that patch occupancy models may provide simple methods for analyzing population dynamics in heterogeneous landscapes in the context of global change.

解析变化生境中的种群动态 (population dynamics)，是实现种群动态预测的前提条件。近年来集合种群模型 (metapopulation modeling) 的发展，使得研究者可基于定殖模式 (colonization pattern) 估算扩散核 (dispersal kernels)，但这类估算与种子扩散核 (seed dispersal kernel) 的直接估算之间的准确性对比，却极少得到评估。本研究采用基于亲权分析 (parentage analysis) 的新兴遗传方法，依托空间显性交配模型 (spatially explicit mating models)，对斑块动态存在差异的城市破碎化种群——植物物种硬枝还阳参 (Crepis sancta) 的种子与花粉扩散核 (pollen dispersal kernels)，以及种子和花粉迁入情况进行了估算。依托两个独立研究网络 (independent networks)，本研究记录到了大量的种子迁入 (seed immigration)，且扩散核高度受限。此外，不同网络间的迁入异质性 (immigration heterogeneity) 与此前报道的集合种群动态相符，表明第一个研究网络的定殖主要源于外部定殖 (external colonization)，即繁殖体雨 (propagule rain)，而第二个网络的定殖则以局部定殖 (local colonization) 为主。本研究得出结论：城市斑块动态 (urban patch dynamics) 的差异主要源于种子迁入异质性，这凸显了外部种群源在破碎化景观 (fragmented landscape) 中植物时空动态 (spatio-temporal dynamics) 中的重要性。研究结果表明，间接与直接方法 (indirect and direct methods) 在定性层面上保持一致，可为间接估算提供合理的解释依据。本研究尝试将遗传与种群统计方法 (genetic and demographic methods) 相结合，并证实斑块占据模型 (patch occupancy models) 可为全球变化 (global change) 背景下异质性景观中的种群动态分析提供简便可行的研究手段。