四種靈長類消化道停留時間與食物中纖維含量和種子發芽率的關係

Abstract

種子通過食果者消化道的停留時間(Gut retention time, GRT)不同，不僅會影響種子被傳播的空間分布，還可能影響到種子的發芽率。靈長類經常取食多種果實種子，且大部分被取食過的種子仍會發芽，因此被認為是植物種子的重要傳播者。過往有關靈長類消化道停留時間的研究顯示：食物中纖維來源與份量的不同會顯著造成消化道停留時間的差異。本研究利用屏東科技大學野生動物收容中心內的台灣獼猴(Macaca Cyclopis)、馬來獼猴(Macaca fascicularis )、長臂猿(Hylobates lar)及紅毛猩猩(Pongo pygmmaeus)等四種後腸發酵靈長類來檢驗食物中纖維比例與消化道停留時間的關係，並利用無休眠性的稜果榕(Ficus septica)以及淺休眠性的山黃麻(Trema orientalis)來檢驗消化道停留時間的長短對種子發芽率的影響。結果顯示四種靈長類中僅長臂猿 (20.6±0.6/24.5±0.7 hr) 及紅毛猩猩 (124.7±9.0/146.5±11.4 hr)消化道停留時間會隨著食物中纖維量增加而增加。雖然九月及十一月採集的稜果榕種子有不同的發芽率 (100%; 63%)，但大部份通過靈長類消化道的稜果榕種子發芽率顯著低於控制組種子，發芽天數也顯著增加。而山黃麻種子則是在通過台灣獼猴及紅毛猩猩的消化道後有較低發芽率及較短的發芽時間。因此，不同纖維比例的食物會造成靈長類消化時間的改變，進而改變了種子的空間分布與其發芽狀況。

Gut retention time (GRT), which is defined as the time needed for seeds swallowed by frugivores to pass the digestive tracts, may affect both the germination rate and spatial distribution of seeds. Previous GRT studies indicated that the source and amount of fibers in the diet may cause significant variation in the GRT of primates, which are important seed dispersers because they consume a large amount of fruits and defecate lots of viable seeds, and affect seed germination. This study was set to investigate the relationship between the fiber content in diets and GRT in four hindgut-fermenting primate species (Macaca cyclopis, M. fascicularis, Hylobates lar, and Pongo pygmmaeus), and the effect of GRT on germination rate of seeds with different types of dormancy, i.e. the non-dormancy seeds (Ficus septica) and shallow dormancy seeds (Trema orientalis). The GRT was longer for digesting higher fiber ratio diets in Hylobates lar (LF: 20.6±0.6 vs. HF: 24.5±0.7 hr) and P. pygmmaeus (LF: 124.7±9.0 vs. HF: 146.5±11.4 hr), but not in macaques. The germination percentages of F. septica seeds in control group were different between seeds collected in September and November (100%; 63%). Nevertheless, the germination percentage of most F. septica seeds after passing guts of primates was lower and germination time was longer than controls. Trema orientalis seeds had lower germination percentage and shorter germination time after passing guts of M. cyclopis and P. pygmmaeus. GRT impacted the germination percentage and germination time of F. septica seeds but the impact was different on T. orientalis seeds. In conclusion, different fiber content diet may cause GRT variation in primates, and thus affect spatial distribution and germination pattern of seeds when they swallowed.