一些啮齿类动物在取食植物种子的同时还对部分种子进行分散贮藏，这种行为对一些大粒种子植物的扩散至关重要。种子的特征影响啮齿类动物的喜好，但由于自然界种子不同性状特征鳌合在一起，要弄清楚哪种性状影响啮齿类动物的选择行为实属不易。近日，中科院西双版纳热带植物园博士研究生王博及其导师陈进研究员通过设计一种人工种子和一组试验，巧妙地解决了上述难题，该研究成果发表在国际权威杂志Ecology。

该研究在云南西北部中甸高山植物园内的一片天然松林里进行，研究人员用泥土做成种子形状，通过改变大小和人工种子的填充物比例来探讨种子大小、单宁含量以及营养成分对分散贮藏习性啮齿类动物的影响。该森林内进行种子分散埋藏的主要是二种姬鼠（Apodemus）。研究结果表明，姬鼠就地取食小种子，搬运埋藏中等大小的种子（直径1.2—2.5cm），并且种子越大被搬运的距离越远。种子的营养和单宁含量也同样显著影响啮齿类动物的行为，但这种影响在不同年份表现不一致。啮齿类动物也表现出一定程度的选择多个性状最优的种子。但总体上看，种子大小对这种具分散贮藏习性的啮齿类动物在种子取食和散布的选择中起决定性的作用。该研究结果还提示乔木植物可以通过简单地增大种子大小来提高种子的长距离散布能力。该人工种子研究系统还为今后进一步研究植物和啮齿类动物的相互关系及协同进化提供方法上的借鉴。

原始出处：

Ecology: Vol. 90, No. 11, pp. 3023-3032. doi: 10.1890/08-2188.1

Seed size, more than nutrient or tannin content, affects seed caching behavior of a common genus of Old World rodents

Bo Wang1,2 and Jin Chen1,3

1CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan Province 666303, China
2Graduate School of Chinese Academy of Sciences, Beijing 100049, China

Scatter-hoarding rodents play an important dispersal role for many large-seeded plants. Seed traits affect their foraging behavior; however, it is difficult to isolate their effects because of the covariance among traits. Here, we used artificial seeds to partition the effects of seed size, tannin content, and nutrient content on scatter-hoarding rodents in a natural pine forest in Northwest Yunnan, China. Apodemus, a common genus of Old World rodents, consistently consumed small seeds in situ but removed medium-sized seeds (1.2–2.5 cm in diameter) and transported bigger seeds farther. Seed nutrient and tannin contents also significantly influenced rodents' behavior, but response varied substantially between years. Rodent behavior did involve some aspects of multivariate optimization. Our results strongly indicate that seed size is a decisive factor for scatter-hoarding rodents in the choice between seed predation and dispersal, while nutrient and tannin content played a less consistent role, possibly responding to confounding factors in the community. This result also has important implications for seed production by trees, which can improve the probability of long-distance dispersal of high-quality offspring by simply making them larger. The ability to tease apart the relative influence of different seed traits on the behavior of predators provides powerful insight into this important coevolutionary dynamic.