Figuerola Jordi, Charalambidou Iris, Santamaria Luis, Green Andy J
Department of Wetland Ecology, Estación Biológica de Doñana, CSIC, Apartado de Correos 1056, E-41080, Sevilla, Spain.
Naturwissenschaften. 2010 Jun;97(6):555-65. doi: 10.1007/s00114-010-0671-1. Epub 2010 Apr 29.
Long distance dispersal may have important consequences for gene flow and community structure. The dispersal of many plants depends on transport by vertebrate seed dispersers. The shapes of seed shadows produced by vertebrates depend both on movement patterns of the dispersers and on the dynamics and effects of passage through the disperser's gut (i.e. the retention time, survival and germination of ingested seeds). A combination of experiments with captive waterbirds and aquatic plant seeds was used to analyse the following: (a) the effects of inter- and intra-specific variation in seed size and duck species on seed retention time in the gut and (b) the relationship between retention time and the percent germination and germination rates of seeds. Among the three Scirpus species used, those with smaller seeds showed higher survival after ingestion by birds and longer retention times inside their guts than those with larger seeds. For Potamogeton pectinatus, only seeds from the smaller size class (<8 mg) survived ingestion. Retention time affected the percent germination and germination rate of Scirpus seeds but in a manner that varied for the different plant and bird species studied. We recorded both linear and non-linear effects of retention time on percent germination. In addition, germination rate was positively correlated with retention time in Scirpus litoralis but negatively correlated in Scirpus lacustris. Small seed size can favour dispersal over larger distances. However, the effects of retention time on percent germination can modify the seed shadows produced by birds due to higher percent germination of seeds retained for short or intermediate periods. The changes in dispersal quality associated with dispersal distance (which is expected to be positively related to retention time) will affect the probability of seedling establishment over longer distances and, thus, the spatial characteristics of the effective seed shadow.
长距离扩散可能对基因流动和群落结构产生重要影响。许多植物的扩散依赖于脊椎动物种子传播者的运输。脊椎动物产生的种子扩散阴影的形状既取决于传播者的移动模式，也取决于种子通过传播者肠道的动态过程和影响（即摄入种子的滞留时间、存活率和发芽率）。通过圈养水鸟和水生植物种子的实验组合，分析了以下内容：（a）种子大小和鸭类物种的种间和种内变异对种子在肠道内滞留时间的影响，以及（b）滞留时间与种子发芽率和发芽速率之间的关系。在所使用的三种镳草属植物中，种子较小的物种在被鸟类摄入后显示出更高的存活率，并且在其肠道内的滞留时间比种子较大的物种更长。对于篦齿眼子菜，只有较小尺寸等级（<8毫克）的种子在被摄入后存活下来。滞留时间影响了镳草属种子的发芽率和发芽速率，但对于所研究的不同植物和鸟类物种，其影响方式有所不同。我们记录了滞留时间对发芽率的线性和非线性影响。此外，发芽速率在海滨镳草中与滞留时间呈正相关，但在湖生镳草中呈负相关。小种子尺寸有利于更远距离的扩散。然而，滞留时间对发芽率的影响可能会改变鸟类产生的种子扩散阴影，因为短时间或中等时间滞留的种子发芽率更高。与扩散距离相关的扩散质量变化（预计与滞留时间呈正相关）将影响更远距离上幼苗建立的概率，从而影响有效种子扩散阴影的空间特征。
