Qian Hanrui, Li Wenbo, Li Jinhua
School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China.
International Collaborative Research Center for Huangshan Biodiversity and Tibetan Macaque Behavioral Ecology, Anhui University, Hefei 230601, China.
Animals (Basel). 2022 May 31;12(11):1416. doi: 10.3390/ani12111416.
There are numerous ecological and evolutionary implications for the ability of frugivores to predate on fruits and consume or disperse their seeds. Tibetan macaques, which are considered important seed predators, typically feed on fruits or seeds. However, systematic research into whether they have a seed dispersal function is still lacking. Endozoochory allows seeds to disperse over greater distances by allowing them to remain in the animal’s digestive tract. Consumption of fruit may not imply effective seed dispersal, and the physical characteristics of seeds (e.g., size, weight, specific gravity, etc.) may influence the dispersal phase’s outcome. We conducted feeding experiments with three captive Tibetan macaques (Macaca thibetana) and nine plant seeds to determine the influence of seed characteristics on Tibetan macaques’ early stages of seed dispersal. The results revealed that the percentage of seed destruction (PSD) after ingestion was 81.45% (range: 15.67−100%), with the PSD varying between plant species. Among the three passage time parameters, the transit time (TT) (mean: 18.8 h and range: 4−24 h) and the time of seed last appearance (TLA) (mean: 100.4 h and range: 48−168 h) differed significantly between seed species, whereas the mean retention time (MRT) (mean: 47.0 h and range: 32−70.3 h) did not. In terms of model selection, PSD was influenced by seed size, weight, volume, and specific gravity; TT was influenced by seed-to-shell investment rate, weight, volume, and specific gravity; and TLA was influenced only by seed size. These findings imply that seeds with a smaller size, specific gravity, volume, and greater weight pass more easily through the monkeys’ digestive tracts. Particularly, seeds with a mean cubic diameter (MCD) of <3 mm had a higher rate of expulsion, larger volume, and weight seeds pass faster, while smaller remained longer. Tibetan macaques, as potential seed dispersers, require specific passage time and passage rates of small or medium-sized seeds. Larger and heavier seeds may be more reliant on endozoochory. Tibetan macaques have the ability to disperse seeds over long distances, allowing for gene flow within the plant community.
食果动物捕食果实并消耗或传播其种子的能力具有众多生态和进化意义。藏猕猴被认为是重要的种子捕食者，通常以果实或种子为食。然而，关于它们是否具有种子传播功能的系统研究仍然缺乏。内吞传播使种子能够通过在动物消化道内停留而传播到更远的距离。食用果实并不一定意味着有效的种子传播，种子的物理特征（如大小、重量、比重等）可能会影响传播阶段的结果。我们对三只圈养的藏猕猴（Macaca thibetana）和九种植物种子进行了喂食实验，以确定种子特征对藏猕猴种子传播早期阶段的影响。结果显示，摄入后种子破坏百分比（PSD）为81.45%（范围：15.67−100%），PSD因植物种类而异。在三个通过时间参数中，传播时间（TT）（平均值：18.8小时，范围：4−24小时）和种子最后出现时间（TLA）（平均值：100.4小时，范围：48−168小时）在种子种类之间存在显著差异，而平均保留时间（MRT）（平均值：47.0小时，范围：32−70.3小时）则没有。在模型选择方面，PSD受种子大小、重量、体积和比重的影响；TT受种子与种壳投入率、重量、体积和比重的影响；而TLA仅受种子大小的影响。这些发现表明，尺寸较小、比重较小、体积较小且重量较大的种子更容易通过猴子的消化道。特别是，平均立方直径（MCD）<3毫米的种子排出率更高，体积较大和重量较大的种子通过速度更快，而较小的种子停留时间更长。作为潜在的种子传播者，藏猕猴需要特定的中小尺寸种子的通过时间和通过率。更大、更重的种子可能更依赖内吞传播。藏猕猴有能力将种子传播到很远的距离，从而促进植物群落内的基因流动。
