Wróbel Aleksandra, Zwolak Rafał
Department of Systematic Zoology, Institute of Environmental Biology, Adam Mickiewicz University, Poland.
Integr Zool. 2017 Nov;12(6):457-467. doi: 10.1111/1749-4877.12265.
The sizes of both seed dispersers and seeds are traits that are likely to interact to influence seed fate in many synzoochoric plant species. Here, we examined whether members of a granivorous rodent community consisting of species of different body size vary in their effectiveness as seed dispersers, and how this relationship may be altered by seed size. We marked northern red oak (Quercus rubra) acorns with plastic tags and placed them in size-selective rodent exclosures. The exclosures allowed differential access of rodent groups based on different body size: (i) small (e.g. Peromyscus spp.); (ii) small and medium (e.g. Tamias striatus); and (iii) small, medium and large (e.g. Sciurus carolinensis) species of rodents. Acorn removal did not differ among exclosure types, but more seeds were missing when removed by small rodents, probably because of larderhoarding. The treatments did not influence the relative frequency of acorn consumption. However, small rodents cached considerably fewer and partially ate more acorns than the other 2 groups. The mean dispersal distance was the longest for cages with medium openings, intermediate for cages with large openings and the shortest for cages with small openings. Acorn mass positively affected the probability of caching and this relationship was unaffected by exclosure type. In conclusion, granivorous rodents of different body sizes strongly differed in their interactions with acorns, with small rodents acting primarily as acorn predators and medium and large species contributing significantly more to dispersal of red oaks.
种子传播者和种子的大小都是可能相互作用以影响许多同域传播植物物种种子命运的特征。在这里，我们研究了由不同体型物种组成的食谷啮齿动物群落成员作为种子传播者的有效性是否存在差异，以及这种关系如何因种子大小而改变。我们用塑料标签标记了北方红栎（Quercus rubra）的橡子，并将它们放置在具有大小选择性的啮齿动物围栏中。这些围栏允许不同体型的啮齿动物群体有不同的进入机会：（i）小型（如白足鼠属物种）；（ii）小型和中型（如条纹花栗鼠）；以及（iii）小型、中型和大型（如卡罗来纳松鼠）啮齿动物物种。橡子的移除在不同围栏类型之间没有差异，但被小型啮齿动物移除时更多种子失踪了，可能是因为集中贮藏。这些处理没有影响橡子被消耗的相对频率。然而，小型啮齿动物贮藏的橡子明显更少，且比其他两组更多地部分吃掉了橡子。平均传播距离对于中等开口的笼子最长，对于大开口的笼子居中，对于小开口的笼子最短。橡子质量对贮藏概率有积极影响，并且这种关系不受围栏类型的影响。总之，不同体型的食谷啮齿动物与橡子的相互作用存在很大差异，小型啮齿动物主要充当橡子捕食者，而中型和大型物种对红栎的传播贡献显著更大。
