Footprints of Butterfly Rhodopsin Functional Evolution

许多昆虫的眼睛和大脑具有颜色视觉的潜力，即无论强度或亮度如何，都能区分不同波长的光。这是由于光感受器细胞中表达不同类型的光敏视觉色素视紫红质分子所致。蝴蝶视觉系统对绿色和红色敏感的视紫红素对光的敏感度有巨大的生理变化。像其他视觉色素一样，红色敏感的视紫红质可能会赋予那些拥有它们的生物体一些适应优势，比如在检测花朵、寄主植物和配偶方面。与大多数节肢动物中发现的对紫外线、蓝色或绿色敏感的视觉色素不同，并不是所有的蝴蝶或昆虫都进化出对红色敏感的色素，这可能是因为产生它们的一些基本限制或代谢成本。拟议的项目将涉及大量若虫的视蛋白基因的特征，这些蝴蝶的视觉色素吸收光谱最大值已被测量，其分类关系已从独立的分子和形态数据中得知。这些数据将被用来识别功能上重要的氨基酸替换，这些替换负责对光敏感的生理变化。该项目将涉及国际合作，并为视觉研究方面的博士后和研究生提供多层次的综合培训，并包括本科生外展部分，本科生将在PI的实验室接受基本分子生物学技术培训。这项工作将引起行为生态学、感觉生物学、机器视觉和比较功能基因组学研究人员的兴趣。

Many insects are equipped with eyes and brains that have the potential for color vision, the ability to distinguish wavelengths of light from one another regardless of intensity or brightness. This results from the expression of different kinds of light sensitive visual pigment rhodopsin molecules in photoreceptor cells. Butterfly visual systems have tremendous physiological variation in the sensitivity of their green- and red-sensitive rhodopsins to light. Like other visual pigments, red-sensitive rhodopsins may confer some adaptive advantage to those organisms that have them, such as in the detection of flowers, host plants and mates. Unlike the UV-, blue-, or green-sensitive visual pigments found in most arthropods, not all butterflies or insects have evolved red-sensitive pigments perhaps because of some basic constraint or metabolic cost of producing them. The proposed project will involve the characterization of opsin genes from a large number of nymphalid butterflies whose visual pigment absorption spectrum maximum has been measured, and whose taxonomic relationships are already known from independent molecular and morphological data. The data will be used to identify functionally important amino acid substitutions that are responsible for physiological shifts in sensitivity to light. The project will involve international collaborations and provide multi-level integrative training for a postdoctoral and graduate student in vision research, and includes an undergraduate outreach component, whereby undergraduates will be trained in basic molecular biology techniques in the PI's lab. The work will be of interest to workers in behavioral ecology, sensory biology, machine vision and comparative functional genomics.