Evolution and development of polyphenisms: a mechanistic model based on bistable switches

多型性代表了一种适应性表型可塑性的形式，它基于发育开关产生离散的替代表型。然而，现有的多型性演化模型没有考虑发育的作用，因此无法解释转换行为的出现和演化。在这个研究项目中，我的目标是揭示如何通过模拟其潜在的发展监管架构的演变多表型演变。主要的研究目标是测试的假设，多表型是基于在潜在的基因调控网络（GRN），这通常需要正反馈和超灵敏度的开关。为了验证这一假设，我将开发一个理论机制模型，重点是负责多效开关的GRN的演变。我预计，在有利于多型性进化的条件下，GRN中将出现正反馈和超灵敏度，从而产生多型性开关。然后，我将使用该模型来调查的影响，监管架构的进化多型。除了一般的模型版本，它可以适用于广泛的多型现象，我还将开发一个具体的模型版本，专门针对环境的性别决定，并利用它来研究性别决定系统的进化过渡是如何介导的GRNs的进化。连接进化生物学和系统生物学，这个研究项目应该在几个方面促进我们对多型现象的理解。首先，该项目提供了一个新的，基于GRN的发展基础上的多表现象的角度。因此，它能够解释阈值行为和表型稳定性的多型现象。此外，这种方法使我们能够解决关键的尚未探索的问题，并作出可检验的预测，关于多型现象的演变，以及它是如何取决于潜在的监管条件。

Polyphenisms represent a form of adaptive phenotypic plasticity that gives rise to discrete alternative phenotypes, based on a developmental switch. However, existing models for the evolution of polyphenisms do not consider the role of development and therefore cannot explain how the switching behavior emerges and evolves. In this research project, I aim to reveal how polyphenisms evolve by modeling the evolution of their underlying developmental regulatory architecture. The main research objective is to test the hypothesis that polyphenisms are based on bistable switches in the underlying gene regulatory network (GRN), which usually requires positive feedback and ultrasensitivity. To test this hypothesis, I will develop a theoretical mechanistic model that focuses on the evolution of the GRN responsible for the polyphenism switch. I expect that, under conditions favorable to the evolution of a polyphenism, both positive feedback and ultrasensitivity will emerge in the GRN, giving rise to a polyphenism switch. I will then use the model to investigate the implications of the regulatory architecture for the evolution of polyphenisms. In addition to the general model version, which can be applied to a wide range of polyphenisms, I will also develop a concrete model version specifically tailored to environmental sex determination and employ it to study how evolutionary transitions in sex-determining systems are mediated by the evolution of GRNs. Connecting evolutionary biology and systems biology, this research project should advance our understanding of polyphenisms in several ways. First, the project offers a novel, GRN-based perspective on the developmental basis of polyphenisms. Thus, it is able to explain both the threshold behavior and the phenotypic stability of polyphenisms. Moreover, the approach allows us to address critical yet unexplored questions, and make testable predictions, about the evolution of polyphenisms and how it is contingent upon underlying regulatory conditions.