Collaborative Research: Developmental and functional mechanisms of complex trait re-evolution: Limb loss and gain in skink lizards

理解复杂性格是如何进化的，是发展性格进化基本理论的核心。 其中一个理论，多洛定律，指出一旦失去，复杂的字符不能重新进化，已经挑战了生物学家超过世纪。 尽管最近的证据表明，复杂的字符可以和重新进化，有一个缺乏了解如何以及为什么这些进化逆转发生。 这项研究将通过阐明复杂性状再进化的功能基础和发展机制来解决这些问题。该项目将在一个进化的框架中实现功能形态学和发育遗传学的前所未有的整合，促进这些领域之间的交流。该研究项目将使用一种综合的方法，在系统发育框架中综合发育遗传学和功能形态学，研究东南亚穴居蜥蜴属Brachymeles的肢体和趾缺失以及随后的再进化。 拟议研究的目标是确定已经丢失的表型性状是否重新进化为具有相同或不同的功能能力，以及重新进化的手指是否通过与祖先手指相同或不同的发育机制发育。 将使用高速视频和力传感器对祖先和重新进化的五趾动物、中间动物和无肢物种的表面运动速度、加速度和穴居速度和力进行量化。四肢和手指的减少和再进化的发展基础Brachymeles的特点，以确定假设的发展限制肢体和手指的再进化。 胚胎中手指间充质致密化将通过组织化学和与肢体和手指图案相关的九个基因的原位杂交来鉴定。该项目还将涉及和培训研究方法的本科生和研究生，并将促进国际合作。 将积极招募和鼓励少数民族学生和女学生参加该项目提供的研究培训机会。 该项目产生的生物主题外展计划将针对弱势社区和当地K-12学校。 拟议项目的调查结果将作为已建立的生物多样性信息网站（http：//philbreo.lifedesks.org/）的一部分在网上、在科学会议上、在同行评审的期刊上以及通过其他现有数据库（http：//datadryad.org/）公开传播。

Understanding how complex characters evolve is central to developing fundamental theories of trait evolution. One such theory, Dollo's Law, which states that once lost, complex characters cannot be re-evolved, has challenged biologists for more than a century. Despite recent evidence suggesting that complex characters can and do re-evolve, there is a lack of understanding of how and why these evolutionary reversals take place. The proposed study will address these questions by elucidating the functional underpinnings and the developmental mechanisms of complex trait re-evolution. This project will result in an unprecedented integration of functional morphology and developmental genetics in an evolutionary framework, facilitating communication between these fields.The research project will use an integrative approach that synthesizes developmental genetics and functional morphology in a phylogenetic framework to study limb and digit loss and subsequent re-evolution in the Southeast Asian burrowing lizard genus Brachymeles. Objectives of the proposed research are to determine whether a phenotypic trait that has been lost re-evolves with the same or different functional capacities, and whether re-evolved digits develop via the same or different developmental mechanisms as ancestral digits. Surface locomotor velocity, acceleration, and burrowing speed and force will be quantified using high-speed video and a force transducer for ancestrally and re-evolved pentadactyl, intermediate, and limbless species. The developmental basis of limb and digit reduction and re-evolution in Brachymeles will be characterized to identify hypothesized developmental constraints on limb and digit re-evolution. Mesenchymal condensations of digits in embryos will be identified using histochemistry and in situ hybridization of nine genes associated with limb and digit patterning. The project will be also involve and train undergraduate and graduate students in research methods and will promote international collaborations. Minority and female students will be actively recruited and encouraged to participate in the research training opportunities provided by the project. Biologically themed outreach programs resulting from this project will target disadvantaged communities and local K-12 schools. Findings from the proposed project will be publicly disseminated online as part of an established biodiversity information website (http://philbreo.lifedesks.org/), at scientific conferences, in peer-reviewed journals, and through other existing databases (http://datadryad.org/).