EDGE CMT: Origin and diversification of butterfly color patterns

当我们审视生命的多样性时，我们看到了许多特定有机体群体所独有的复杂特征。例如，鸟类的羽毛，哺乳动物的毛发，被子植物的花。这些新奇的特征最初是如何出现的，这是生物学中的一个主要问题。新颖性的基因基础是什么？最近对许多物种的研究表明，像这样的新特征很大程度上是由旧基因产生的，这些旧基因已经被重新定位为新的角色。新颖性似乎是通过重新洗牌旧的基因构建块出现的，这些构建块被认为是古老的相互作用的基因子网络。但这些基因网络最初从何而来呢？它们是如何重新连接以产生复杂的新特征的？有了这笔资金，里德和他的同事们开始通过观察蝴蝶颜色的起源来解决这些问题。他们正在描述蝴蝶颜色着色背后的基因网络，他们正在确定特定的遗传变化如何导致这些网络从祖先在神经发育等过程中的角色改变用途，以形成蝴蝶的翅膀图案。这项工作作为一个案例研究，帮助生物学家了解复杂生物特征的起源和多样化背后的发育遗传机制。该项目还包括培训来自不同背景的研究生和本科生的生物学研究技能，开发和传播基因组学方法的教学视频，以及建立一个基于网络的蝴蝶功能基因组学资源。现代生物学的一个核心概念是，新的形态特征起源于早于特征本身的基因调控网络。然而，令人惊讶的是，人们对这种基因网络的起源和再利用的具体遗传机制知之甚少。有了这笔资金，Reed和他的同事们将包含蝴蝶颜色图案基因Optix的调控网络开发成一个模型，用于探索特征多样化的调控架构。Optix是一种同源框转录因子，在无脊椎动物和脊椎动物的神经和视网膜发育中发挥着深远的祖先作用。然而，在蝴蝶中，这个基因经历了一个激进的共同选择事件，在那里它获得了一个新的功能，作为翅膀色素沉积的主要调节，包括在适应和模仿中发挥关键作用。因此，研究人员在鳞翅目的情况下，他们可以准确地确定一个重大的Optix共同选择和改变用途的事件的系统发育时间，其中该基因作为颜色模式的从头调节出现。Reed及其同事正在利用这一机会，采用多物种比较的方法来描述Optix调节网络的历史，因为它在颜色模式调节中获得了新的适应功能。使用Optix作为焦点，他们正在表征监管增选的顺式、上游和下游监管动态，并构建一个全面的案例研究，说明新的基因监管网络如何从基因组中出现，以产生新的形态特征-在这种情况下，颜色本身。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。

When we look across the diversity of life, we see many complex traits that are unique to certain groups of organisms. Feathers in birds, hair in mammals, and flowers in angiosperms, for example. It is a major question in biology how these kinds of novel traits first appear. What is the genetic basis of newness? Recent work across many species has shown that novel traits such as these are largely generated by old genes that have been repurposed for new roles. Novelty appears to emerge through a reshuffling of older genetic building blocks, which are proposed to be ancient subnetworks of interacting genes. But where do these gene networks come from in the first place? And how are they rewired to generate complex new traits? With this funding, Reed and colleagues are beginning to address these questions by looking at the origin of color in butterflies. They are characterizing the gene networks that underlie color pigmentation in butterflies, and they are determining how specific genetic changes caused these networks to be repurposed from ancestral roles in processes such as neural development, to make butterfly wing patterns. This work serves as a case study to help biologists understand the developmental genetic mechanisms that underlie the genesis and diversification of complex biological traits. The project also includes training in biology research skills of graduate and undergraduate students from diverse backgrounds, the development and dissemination of instructional videos for genomic methods, and the establishment of a web-based resource for functional genomics in butterflies.A core concept in modern biology is that novel morphological traits originate from gene regulatory networks that predate the traits themselves. Surprisingly, however, little is known about the specific genetic mechanisms that underlie the origin and repurposing of such gene networks. With this funding, Reed and colleagues develop the regulatory network encompassing the butterfly color pattern gene optix into a model for exploring the regulatory architecture of trait diversification. optix is a homeobox transcription factor that plays a deeply ancestral role in neural and retinal development in both invertebrates and vertebrates. In butterflies, however, this gene underwent a radical co-option event where it gained a novel function as a master regulator of wing pigmentation, including playing key roles in adaptation and mimicry. Thus, the researchers have a situation in Lepidoptera where they can pinpoint the phylogenetic timing of a major optix co-option and repurposing event, where this gene appeared as a de novo regulator of color patterns. Reed and colleagues are leveraging this opportunity to take a multi-species comparative approach to characterize the history of the optix regulatory network as it gained its novel adaptive function in color pattern regulation. Using optix as the focal point, they are characterizing the cis-, upstream, and downstream regulatory dynamics of regulatory co-option, and construct a comprehensive case study of how a new gene regulatory network can emerge from the genome to generate new morphological features – in this case, color itself.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.