Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
Department of Neuroscience, Wellesley College, Wellesley, MA 02481, USA.
Curr Biol. 2024 Oct 21;34(20):4743-4755.e3. doi: 10.1016/j.cub.2024.08.036. Epub 2024 Sep 17.
Maintaining stable gaze while tracking moving objects is commonplace across animal taxa, yet how diverse ecological needs impact these processes is poorly understood. During flight, the fruit-eating fly Drosophila melanogaster maintains course by making smooth steering adjustments to fixate the image of the distant visual background on the retina, while executing body saccades to investigate nearby objects such as food sources. Cactophilic Drosophila mojavensis live where there is no canopy; rather, the flora forming visual "background" and "objects" are one and the same. We tested whether D. mojavensis have adapted their flight control strategies for a visually sparse landscape. We used a magnetic tether that allows free movement in the yaw axis. In response to a textured bar moving across a similarly textured stationary background, D. melanogaster fixates the background, thereby stabilizing gaze while integrating bar dynamics to trigger tracking saccades. By contrast, two mojavensis subspecies in the repleta subgroup and one species in the melanogaster subgroup steer to smoothly fixate the bar, seemingly ignoring the stationary surround. Desert flies execute frequent bar-tracking saccades, but theirs are triggered when rotational velocity lags the bar. Thus, D. melanogaster, which lives in visually cluttered cosmopolitan habitats, leverages the optical disparities between nearby objects and distant foliage for a hybrid control strategy: "ground-fixate, object-saccade." Flies in distant phylogenetic subgroups with similar visual ecology use a "fixate-and-saccade" strategy, which would be adaptive in a visually sparse environment where individual landscape features are both approached and used to maintain a straight course.
在动物分类中，稳定注视跟踪移动物体是一种常见现象，但生态需求的多样性如何影响这些过程还知之甚少。在飞行中，食果果蝇通过对远处视觉背景的视网膜进行平滑的转向调整来保持航向，同时执行身体扫视以调查食物等附近物体，从而保持飞行方向。生活在没有树冠的地方的仙人掌果蝇，其视觉“背景”和“物体”是同一的。我们测试了 D. mojavensis 是否已经适应了它们的飞行控制策略，以适应视觉稀疏的景观。我们使用一个允许在偏航轴上自由移动的磁系绳。当一个带有纹理的棒在一个具有相似纹理的静止背景上移动时，D. melanogaster 会固定背景，从而在整合棒动态以触发跟踪扫视的同时稳定注视。相比之下，repleta 亚组的两个 mojavensis 亚种和 melanogaster 亚组的一个物种会平稳地转向以固定棒，似乎忽略了静止的周围环境。沙漠蝇会执行频繁的棒跟踪扫视，但它们的扫视是在旋转速度滞后于棒时触发的。因此，生活在视觉杂乱的世界性栖息地的 D. melanogaster 利用了附近物体和远处树叶之间的光学差异，采用了一种混合控制策略：“地面固定，物体扫视”。在具有相似视觉生态学的遥远系统发育亚组中，苍蝇使用“固定和扫视”策略，这在视觉稀疏的环境中是适应性的，在这种环境中，个体景观特征既被接近又被用来保持直线飞行。
