Reppert Steven M, Zhu Haisun, White Richard H
Department of Neurobiology, University of Massachusetts Medical School, LRB-728, 364 Plantation Street, Worcester, MA 01605, USA.
Curr Biol. 2004 Jan 20;14(2):155-8. doi: 10.1016/j.cub.2003.12.034.
During their spectacular migratory journey in the fall, North American monarch butterflies (Danaus plexippus) use a time-compensated sun compass to help them navigate to their overwintering sites in central Mexico. One feature of the sun compass mechanism not fully explored in monarchs is the sunlight-dependent parameters used to navigate. We now provide data suggesting that the angle of polarized skylight (the e-vector) is a relevant orientation parameter. By placing butterflies in a flight simulator outdoors and using a linear polarizing filter, we show that manipulating the e-vector alters predictably the direction of oriented flight. Butterflies studied in either the morning or afternoon showed similar responses to filter rotation. Monarch butterflies possess the anatomical structure needed for polarized skylight detection, as rhabdoms in the dorsalmost row of photoreceptor cells in monarch eye show the organization characteristic of polarized-light receptors. The existence of polarized-light detection could allow migrants to accurately navigate under a variety of atmospheric conditions and reveals a critical input pathway into the sun compass mechanism.
在秋季壮观的迁徙旅程中，北美黑脉金斑蝶（Danaus plexippus）利用时间补偿太阳罗盘来帮助它们导航至墨西哥中部的越冬地点。在黑脉金斑蝶中尚未得到充分探索的太阳罗盘机制的一个特征是用于导航的依赖阳光的参数。我们现在提供的数据表明，偏振天空光的角度（e向量）是一个相关的定向参数。通过将蝴蝶放置在户外飞行模拟器中并使用线性偏振滤光片，我们表明操纵e向量可预测地改变定向飞行的方向。在上午或下午研究的蝴蝶对滤光片旋转表现出相似的反应。黑脉金斑蝶拥有检测偏振天空光所需的解剖结构，因为黑脉金斑蝶眼睛中最背侧一排感光细胞中的视杆显示出偏振光感受器的组织特征。偏振光检测的存在可以使迁徙者在各种大气条件下准确导航，并揭示了进入太阳罗盘机制的关键输入途径。
