Changes in circuit motif during evolution of a species-specific behavior.

进化在动物身上产生了各种各样的形态、生理和行为特征。几十年的研究表明，特定基因调控区域的变异与物种形态差异（如翅膀图案）有关。但是，在拥有相似神经元和分子成分的物种中，行为是如何向不同方向进化的呢？解决这些谜团需要理解行为的进化适应性变化与神经回路的结构/功能变化之间的关系。******果蝇（Drosophila）幼虫对这一目的很有用，因为1)果蝇属由许多密切相关的物种组成，它们表现出广泛的行为；2)它们足够小，可以产生整个神经系统的电子显微镜图像；3)遗传工具和高通量行为分析技术使得操纵单个神经元类型以了解它们在神经回路和行为中的功能成为可能。******逃跑行为可能是在巨大的进化压力下进化而来的，因为它们对生存很重要，这为理解行为进化提供了一个特别好的机会。被寄生蜂攻击时，黑腹蝇幼虫会打滚。在实验室里，一种伤害性刺激触发打滚。这种行为背后的核心电路最近已经被绘制出来。初步数据还表明，在几个密切相关的果蝇物种之间，滚动的概率差异很大。这为探索性分析与特定行为变化相关的神经变化奠定了基础。******本提案将确定突触和电路水平的结构/功能变化，这些变化是在定义良好的感觉运动电路中滚动概率分化的基础。目的1将详细比较不同种类果蝇的幼虫逃跑行为。目的2将重建电路背后的滚动，与生理成像实验，以测试电路，生理和行为之间的相关性。结果应该揭示调整滚动概率所需的电路基序，以及电路结构/功能特性的变化如何促进行为进化。******我们的长期目标是了解这些特征的变化如何在电路、细胞和分子水平上改变行为。这一成就将成为著名社会生物学家e·o·威尔逊（E. O. Wilson）所说的“一致性”（consiliding）的首批例证之一。“一致性”是对行为进化的一种理解，它将知识垂直地整合在多个分析层面上，从底层的分子到顶层的行为。

Evolution has generated an enormous variety of morphological, physiological, and behavioral traits in animals. Decades of research have shown that variation in the regulatory regions of particular genes is associated with species differences in morphology (e.g., wing pattern). But how do behaviors evolve in different directions in species equipped with similar neurons and molecular components? Solving these mysteries requires an understanding of the relationship between evolutionarily adaptive changes in behavior and structural/functional changes in neural circuits.******Fruit fly (Drosophila) larvae are useful for this purpose because 1) the Drosophila genus consists of many closely related species that exhibit a wide range of behaviors; 2) they are small enough to generate electron microscope images of the entire nervous system; and 3) the genetic tools and high-throughput behavior analysis techniques available for D. melanogaster make it possible to manipulate single neuron types to understand their function(s) in neural circuits and behavior.******Escape behaviors, which likely evolved under intense evolutionary pressures given their importance for survival, offer a particularly good opportunity to understand behavioral evolution. D. melanogaster larvae roll when attacked by a parasitic wasp. In the laboratory, a nociceptive stimulus triggers rolling. The core circuitry underlying this behavior has recently been mapped out. Preliminary data also show that the probability of rolling varies widely across several closely related Drosophila species. This sets the stage for an exploratory analysis of the neural changes associated with changes in a specific behavior.******This proposal will identify the synapse- and circuit-level changes in structure/function that underlie the divergence of rolling probability in a well-defined sensorimotor circuit. Aim 1 will compare larval escape behaviors in detail across different Drosophila species. Aim 2 will reconstruct the circuitry underlying rolling, with physiological imaging experiments to test for correlations among circuitry, physiology, and behavior. The results should reveal circuit motifs required for adjusting rolling probability, and how variation in the structural/functional properties of circuitry contributes to behavioral evolution in general. ******Our long-term goal is to understand how changes in these features transform behavior at the circuit, cellular, and molecular levels. Such an achievement would constitute one of the first demonstrations of what the renowned sociobiologist E. O. Wilson called consilience—an understanding of behavioral evolution that integrates knowledge vertically across multiple levels of analysis, from molecules at the bottom, to behavior at the top.