RUI: Specification and Evolution of Reproductive Fate in the Pea Aphid

进化允许有机体通过基因突变和自然选择来适应他们的环境，历经许多代。此外，一些生物可以在短短一代人的时间内适应环境的变化，而不需要改变他们的基因。当环境影响生物体的发育，并使生物体比通过进化变化可能更快地适应环境挑战时，就会发生这种“发育可塑性”。可塑性本身是通过更长的突变和选择过程进化的，但人们对这种进化知之甚少。这个项目的重点是蚜虫，这是一种小昆虫，在夏季的几个月里克隆繁殖并生下活的孩子。然而，夏季的形式无法在寒冷的冬天生存下来。在秋天，当蚜虫妈妈感觉到白天越来越短时，它们会发出化学信号，让它们的胚胎后代发育成一种可以产卵的形式，这种卵可以在冬天的寒冷温度下生存，并在春天孵化。该项目的参与者将研究当蚜虫胚胎从夏季转换到秋季时，发育过程中发生的分子变化。参与者还将研究来自暖冬地区的蚜虫，这些地区不再产生秋季形态，也不产卵，试图了解在最近的进化过程中，对较短白天的反应是如何丧失的。这项工作将主要在布林·莫尔学院进行，这是一所女子本科院校，因此也旨在吸引年轻女性在进化发育生物学学科内设计和执行假设驱动的实验和数据分析。蚜虫繁殖多物性有望成为自然种群遗传适应的一个重要例子，人们对这种可塑性的发育和内分泌基础有很好的了解。然而，这样的进展将需要对该体系的基本原理有一个准确的了解。尽管有几条证据表明，保幼激素参与了光周期反应，但这种激素在调节这一效应中所起的确切作用尚不清楚。激素调控、保幼激素滴度的测量以及早期具型和随后进入夏秋季分化过程中的基因表达的综合方法，将区分保幼激素在这一过程中所起作用的相互竞争的假说。如果成功，这些实验可以证明保幼激素在决定生殖命运中的胚胎作用，并识别这种分化的其他早期标记，为理解这种开关以及它如何进化以适应新的环境提供候选并打开新的大门。

Evolution allows organisms to adapt to their environments over many generations via genetic mutation and natural selection. In addition, some organisms can adapt to changes in their environments within just one generation without any change in their genes. Such "developmental plasticity" occurs when the environment influences how organisms develop, and allows organisms to adapt to environmental challenges more rapidly than is possible through evolutionary change. Plasticity itself has evolved through the longer process of mutation and selection, but little is known about this evolution. This project focuses on aphids, small insects that reproduce clonally and give live birth during the summer months. The summer form, however, cannot survive a cold winter. In the fall, when mother aphids sense that days are getting shorter, they chemically signal their embryonic offspring to develop into a form that can lay eggs that can survive the cold temperatures of winter and hatch in the spring. The participants in this project will investigate the molecular changes that occur in developing aphid embryos when they switch from the summer to the fall form. Participants will also investigate aphids from regions with mild winters that no longer produce the fall form and do not lay eggs, to try to understand how the response to shorter days has been lost over the course of recent evolution. The work will take place primarily at Bryn Mawr College, a women's undergraduate institution, and thus also aims to engage young women in the design and execution of hypothesis-driven experimentation and data analysis within the discipline of evolutionary developmental biology.The aphid reproductive polyphenism is poised to become an important example of genetic accommodation in natural populations, one for which a good deal is known about the developmental and endocrine basis of the plasticity. Such progress, however, will require an accurate understanding of the fundamentals of the system. Although several lines of evidence suggest that juvenile hormone is involved in the photoperiod response, the precise role this hormone plays in mediating the effect is not clear. A combined approach of hormone manipulation, measurements of juvenile hormone titer, and gene expression during early specification and subsequent differentiation into the summer and fall forms will discriminate among competing hypotheses for the role that juvenile hormone plays in the process. If successful, the experiments could demonstrate an embryonic role for juvenile hormone in the specification of reproductive fate and identify other early markers of this differentiation, providing candidates and opening new doors toward understanding the switch and how it evolves to accommodate novel environments.