The roles of exaptive and adaptive co-option in eye evolution

生物学中的一个基本问题是：新的复杂特征，如眼睛，从哪里来，尤其是编码它们的基因从哪里来？尽管从水母到人类的动物拥有许多不同的眼睛类型，但影响光如何转化为视觉化学信号的基因在不同的眼睛中是相似的。有趣的是，在不用于视觉的器官中也发现了一些眼睛感光所必需的基因。因此，眼睛中使用的感光机械可能来自非眼睛来源。这个项目着眼于基因如何在身体的新位置或发育过程中的不同时间开启和关闭，以产生眼睛。通过这样做，它将帮助我们更广泛地了解生物体如何进化以改变其基因的用途，从而创造出全新的器官。这项工作将产生新的基因组序列，可供商业和政府机构用于经济上重要物种的水产养殖开发，如扇贝、牡蛎和文蛤。它还将提高7-12年级教育工作者对进化论的理解，帮助他们实现下一代科学标准目标。这将通过培训他们更好地教授分子进化，以及创建和传播新的教案来向高中生教授分子进化来实现。这项研究还将为博士后研究人员和本科生提供基因组学和生物信息学前沿领域的培训机会。这将提高下一代工人使用基于DNA的工具和分析的技能。了解眼睛的进化起源是生物学家非常感兴趣的，因为眼睛提供了对复杂表型如何通过重新部署和阐述遗传途径而产生的洞察。然而，以前的研究并没有利用拥有不同眼睛类型的密切相关的分类群。这项工作将研究翼形目中一组密切相关的双壳类中眼睛的五个独立来源。利用组织特异性转录本和基因组组装的组合，研究人员将识别涉及跨物种光传导的基因，这些基因跨越翼状动物的分类和眼睛多样性，并在系统发育框架中进行分析，以了解基因表达位置或时间的变化如何在翼状动物眼型多样性的进化中发挥作用。这项工作将解决以下问题：1)有眼睛的谱系是否与光传导途径成员的基因家族的扩展有关？2)物种内和物种间不同的光感受结构之间的光传导基因的相似程度如何？3)眼睛是通过相同的进化过程获得光传导途径，还是每只眼睛都有独特的光接收进化轨迹？这项工作是双壳类眼睛进化的第一次系统发育研究，建立在PI的研究、最近可用的基因组资源和关于光传导途径进化的新数据的基础上。因此，该项目将推进感官系统如何进化的知识。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

A basic question in biology asks: Where do new complex traits, such as eyes, come from, and in particular, where do the genes that encode them come from? Despite the many different eye types possessed by animals from jellyfish to humans, the genes affecting how light is transformed into the chemical signals of seeing are similar across eyes. Interestingly, some of these genes necessary for light-sensing in eyes are also found in organs not used for vision. Therefore, it may be that the light-sensing machinery used in eyes came from a non-eye origin. This project looks at how genes can be turned on and off in a new place in the body or at different times during development to generate eyes. In doing so it will help us more generally to understand how organisms can evolve to repurpose their genes to create entirely new organs. The work will produce new genome sequences that can be used by commercial and governmental agencies in aquaculture development for economically important species, like scallops, oysters, and clams. It will also improve 7-12th grade educators' understanding of evolution to help them achieve the Next Generation Science Standards goals. This will be done by training them to better teach molecular evolution, and creating and disseminating novel lesson plans for teaching molecular evolution to high school students. The research will also provide training opportunities in cutting edge fields of genomics and bioinformatics to postdoctoral researchers and undergraduate students. This will increase the skills of the next generation of workers in using DNA-based tools and analyses. Understanding the evolutionary origin of eyes is of great interest to biologists because eyes provide insight into how complex phenotypes can arise through redeployment and elaboration of genetic pathways. Yet, previous studies have not utilized closely related taxa that possess a diversity of eye types. This work will examine five separate origins of eyes in a group of closely related bivalves in the Pteriomorphia. Using a combination of tissue-specific transcriptomes and genome assembly, the researchers will identify genes involved in phototransduction across species spanning the taxonomic and ocular diversity of the Pteriomorphia and analyze these in a phylogenetic framework to understand how changes to either the location or timing of gene expression has played a role in the evolution of pteriomorphian eye type diversity. The work will address the following questions: 1) Are lineages with eyes associated with gene family expansions of the phototransduction pathway members? 2) What is the degree of similarity of the phototransduction genes between the different photoreceptive structures within and among species? and 3) Do eyes acquire their phototransduction pathways using the same evolutionary process or does each eye have a unique evolutionary trajectory to photoreception? This work is the first phylogenetic investigation of eye evolution in bivalves, and builds on the PIs' research, recently available genomic resources, and new data on phototransduction pathway evolution. The project will thus advance knowledge of how sensory systems evolve.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.