Department of Biology, Lund Vision Group, Lund University, Lund, Sweden.
Department of Computer Science, BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.
J R Soc Interface. 2019 Aug 30;16(157):20190181. doi: 10.1098/rsif.2019.0181. Epub 2019 Aug 7.
Moving along a straight path is a surprisingly difficult task. This is because, with each ensuing step, noise is generated in the motor and sensory systems, causing the animal to deviate from its intended route. When relying solely on internal sensory information to correct for this noise, the directional error generated with each stride accumulates, ultimately leading to a curved path. In contrast, external compass cues effectively allow the animal to correct for errors in its bearing. Here, we studied straight-line orientation in two different sized dung beetles. This allowed us to characterize and model the size of the directional error generated with each step, in the absence of external visual compass cues (motor error) as well as in the presence of these cues (compass and motor errors). In addition, we model how dung beetles balance the influence of internal and external orientation cues as they orient along straight paths under the open sky. We conclude that the directional error that unavoidably accumulates as the beetle travels is inversely proportional to the step size of the insect, and that both beetle species weigh the two sources of directional information in a similar fashion.
沿着直线行进是一项极具挑战性的任务。这是因为，动物在每迈出下一步时，其运动和感觉系统都会产生噪声，导致动物偏离预期路线。当仅依靠内部感觉信息来纠正这种噪声时，每一步产生的方向误差会累积，最终导致路径弯曲。相比之下，外部罗盘线索可以有效地帮助动物纠正其方位的误差。在这里，我们研究了两种不同体型的蜣螂的直线定向能力。这使我们能够在没有外部视觉罗盘线索（运动误差）以及存在这些线索（罗盘和运动误差）的情况下，对每一步产生的方向误差的大小进行描述和建模。此外，我们还建立了模型，以研究蜣螂在开阔天空下沿着直线行进时，如何平衡内部和外部定向线索的影响。我们的结论是，随着昆虫行进，不可避免地会累积方向误差，其大小与昆虫的步幅成反比，并且两种蜣螂物种以相似的方式权衡两种方向信息源。
