Department of Plant Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Sweden.
Comp Biochem Physiol A Mol Integr Physiol. 2011 Dec;160(4):493-7. doi: 10.1016/j.cbpa.2011.08.008. Epub 2011 Aug 16.
The retention time of food in the digestive tract of animals has important implications for digestive physiology. Retention time impacts digestive efficiency and among herbivores affects plant-animal interactions including herbivory and seed dispersal. Poorly studied yet iconic Galápagos tortoises are large-bodied generalist herbivores and ecosystem engineers which migrate seasonally. Potentially variable digesta retention times due to strong seasonal and altitudinal temperature gradients may influence tortoise seed dispersal abilities and rates of herbivory. We fed captive adult tortoises living in semi-natural conditions on Galápagos with inert particles and seeds from locally available fruits to determine whether seed size and ambient temperature influenced retention time. Median retention time varied from 6 to 28days, with a mode of 12days. Seed size had no effect on any of our measures of retention time, but ambient temperature was inversely correlated with retention times. Long retention time facilitates long distance seed dispersal by Galápagos tortoises, which may improve effectiveness. The effect of temperature, which may double from hot lowlands to cold highlands through the seasonal cycle, on tortoise digesta retention time will strongly influence seed dispersal efficiency and may influence patterns of food selection and migration in this species.
食物在动物消化道中的停留时间对消化生理学有重要影响。停留时间影响消化效率，在草食动物中，它还影响包括草食和种子传播在内的植物-动物相互作用。研究较少但具有代表性的加拉帕戈斯象龟是大型的杂食性草食动物和生态系统工程师，它们会季节性迁徙。由于强烈的季节性和海拔温度梯度，潜在的可变食糜停留时间可能会影响龟类的种子传播能力和草食率。我们给生活在半自然环境中的圈养成年象龟喂食惰性颗粒和当地可获得的水果种子，以确定种子大小和环境温度是否影响停留时间。停留时间中位数从 6 天到 28 天不等，模式为 12 天。种子大小对我们测量的停留时间没有任何影响，但环境温度与停留时间呈反比。长停留时间有利于加拉帕戈斯象龟进行远距离的种子传播，这可能会提高传播效率。温度的影响可能会在季节性周期中从低地的炎热到高地的寒冷增加一倍，这将强烈影响龟类食糜的停留时间，可能会影响该物种的食物选择和迁徙模式。
