Data from: Fruit size determines the role of three scatter-hoarding rodents as dispersers or seed predators of a fleshy-fruited Atacama Desert shrub

Scatter-hoarding rodents can act as both predators and dispersers for many large-seeded plants because they cache seeds for future use, but occasionally forget them in sites with high survival and establishment probabilities. The most important fruit or seed trait influencing rodent foraging behavior is seed size; rodents prefer large seeds because they have higher nutritional content, but this preference can be counterbalanced by the higher costs of handling larger seeds. We designed a cafeteria experiment to assess whether fruit and seed size of Myrcianthes coquimbensis, an endangered desert shrub, influence the decision-making process during foraging by three species of scatter-hoarding rodents differing in body size: Abrothrix olivaceus, Phyllotis darwini and Octodon degus. We found that the size of fruits and seeds influenced foraging behavior in the three rodent species; the probability of a fruit being harvested and hoarded was higher for larger fruits than for smaller ones. Patterns of fruit size preference were not affected by rodent size; all species were able to hoard fruits within the entire range of sizes offered. Finally, fruit and seed size had no effect on the probability of seed predation, rodents typically ate only the fleshy pulp of the fruits offered and discarded whole, intact seeds. In conclusion, our results reveal that larger M. coquimbensis fruits have higher probabilities of being harvested, and ultimately of its seeds being hoarded and dispersed by scatter-hoarding rodents. As this plant has no other dispersers, rodents play an important role in its recruitment dynamics.分散贮食啮齿类（scatter-hoarding rodents）对诸多大种子植物而言，兼具捕食者与扩散者的双重身份：它们会将种子贮藏以备日后取用，却偶尔会将种子遗忘在存活率与定植成功率较高的位点。影响啮齿类觅食行为的核心果实或种子性状为种子大小；啮齿类偏好大型种子，因其营养含量更丰富，但该偏好会被处理大型种子所需的更高成本所抵消。本研究针对濒危荒漠灌木Myrcianthes coquimbensis的果实与种子大小，是否会影响3种体型各异的分散贮食啮齿类（Abrothrix olivaceus、Phyllotis darwini与Octodon degus）的觅食决策过程，开展了自选饲喂实验（cafeteria experiment）。研究结果表明，果实与种子大小会影响这3种啮齿类的觅食行为；大型果实被采收并贮藏的概率显著高于小型果实。果实大小偏好模式并未受啮齿类体型的影响；所有受试物种均可贮藏实验提供的全部尺寸梯度范围内的果实。此外，果实与种子大小对种子被捕食的概率无显著影响；啮齿类通常仅取食受试果实的肉质果肉，而将完整无损的种子丢弃。综上，本研究结果表明，体型更大的M. coquimbensis果实被采收的概率更高，其种子最终也更易被分散贮食啮齿类贮藏并扩散。由于该植物无其他有效扩散媒介，啮齿类在其种群更新动态中发挥着关键作用。