Terrestrial Ecology Unit, Biology Department, Ghent University, Ghent, Belgium.
Plant Biol (Stuttg). 2011 Jan;13 Suppl 1:118-24. doi: 10.1111/j.1438-8677.2010.00335.x.
Grazing mammals are regarded as major vectors in seed dispersal of grassland plants, through seed ingestion and subsequent excretion (endozoochory). The (evolutionary) ecology underlying this dispersal mode is relatively poorly understood because there are limited data, among others, on how seed attributes perform in this process (and could thus be selected for). For seed mortality following ingestion, contrasting patterns described for the role of simple seed traits seem partly due to inadequate comparative analytical methods. We conducted a feeding experiment in which controlled seed quantities from 48 grassland herb and grass species were fed to cattle. Seed mass, length and shape measurements were related to seed mortality rate using phylogenetically independent contrasts, which account for taxonomic interdependence. The proportion of seeds surviving the digestive tract was generally low, but it reached 100%, with increased germination for some species. Neither seed size nor shape correlated significantly with mortality. Structural traits are likely to overrule these simple seed traits, as illustrated by high survival of species having water-impermeable seeds. As this trait has interesting properties with respect to intraspecific variation and genetics, it could provide opportunities for inference on evolutionary consequences for this type of dispersal.
食草哺乳动物被认为是草原植物种子传播的主要载体，通过种子摄取和随后的排泄（内动物传播）。这种传播模式的（进化）生态学相对了解较少，因为除其他外，关于种子属性在这个过程中的表现（因此可以选择）的数据有限。对于摄入后的种子死亡率，对于简单种子特性的作用描述的相反模式部分归因于不充分的比较分析方法。我们进行了一项喂养实验，其中将 48 种草原草本植物和草的控制种子数量喂给牛。使用系统发育独立对比（考虑分类学相互依存关系）将种子质量、长度和形状测量值与种子死亡率相关联。种子在消化道中存活的比例通常较低，但对于某些物种，发芽率增加，种子死亡率达到 100%。种子大小或形状与死亡率均无显著相关性。结构特征可能会推翻这些简单的种子特征，例如具有不透水种子的物种的高存活率就是一个例证。由于该特征在种内变异和遗传学方面具有有趣的特性，因此它为推断这种传播方式的进化后果提供了机会。
