Patterns of movement and seed dispersal of a tropical frugivore
Patterns of movement and seed dispersal of a tropical frugivore
复制标题
热带食果动物的运动和种子传播模式
作者：
David A. Westcott;D. L. Graham
摘要 运动是脊椎动物行为的一个基本特征，可以改变种群和群落内的过程。由于热带鸟类食果动物传播许多植物物种的种子，它们活动的时间和空间格局将影响栖息地内的种子分布。到目前为止，人们对这些鸟类的运动模式知之甚少。在这里，我们考虑一种林下食果性食草动物--油菜蛾的运动。使用连续无线电遥测技术监测了16只非繁殖雌性的活动，以提供运动模式的一般描述，并检查运动的空间部分的分形几何。大多数运动是短距离和持续时间的，这两个指标的频率分布都强烈向左倾斜。在所考虑的测量尺度范围内，油松毛虫运动的分维随着测量尺度的增大而增大，最高可达100m左右，之后趋于平缓。我们结合了六种植物种子的运动数据和油菜根结线虫的肠道通过率来预测种子阴影。据估计，六种植物中有四种的种子阴影较小，所有物种的平均传播距离从42到56米。传播距离与报告的花粉传播距离相当，这表明即使是像油菜这样的小种子传播者也可以为植物基因提供显著的传播。肠道通过率似乎决定了种子阴影的形状，而运动则决定了扩散的规模。
Abstract Movement is a fundamental feature of vertebrate behavior and can modify processes within populations and communities. Because tropical avian frugivores disperse seeds of many plant species, the temporal and spatial patterning of their movement will influence seed distribution within a habitat. To date, little is known about movement patterns of these birds. Here we consider the movement of an understory frugivore, Mionectes oleagineus. Movements of 16 non-breeding females were monitored using continuous radio-telemetry to provide a general description of movement patterns and to examine the fractal geometry of the spatial component of movement. Most movements were of short distance and duration, with the frequency distributions of both measures strongly skewed to the left. Over the range of measurement scales considered, the fractal dimension of M. oleagineus’s movement increased with increasing measurement scale up to ca.100 m, whereafter it appeared to flatten out. We combined movement data with M. oleagineus gut-passage rates for seeds of six plant species to predict seed shadows. Estimated seed shadows were leptokurtic for four of the six plant species, with median dispersal distances for all species from 42 to 56 m. Dispersal distances were of the order of reported pollen dispersal distances, suggesting that even small seed dispersers like M. oleagineus can provide significant dispersal for plant genotypes. Gut-passage rate appears to determine the shape of the seed shadow, while movement determines dispersal scale.