Architecture and evolution of gene regulatory networks underlying environmental responses in butterflies

该项目研究非洲蝴蝶如何调整其形态，行为和生命周期以适应不同的环境条件。这种现象被称为表型可塑性，并通过严格调控的发育和调控级联来完成。它在地球仪的许多生物体中进化，因为几乎所有的环境都表现出变异性，特别是在季节之间。当环境发生变化时，是什么基因和途径感知环境并产生不同的表型？这些基因如何在基因调控网络（GRNs）中相互作用？当物种入侵新的栖息地或面临环境变化时，这些GRN是如何进化的？可塑性如何影响未来的适应，例如对气候变化的适应？为了填补这一空白，我们使用一个既定的系统，结合生态相关性，实验的易处理性和基因组资源-非洲Bicyclus蝴蝶。这些物种在从森林入侵季节性稀树草原时，在翅膀图案、行为和生命周期方面一再进化出可塑性。实验室实验表明，蜕皮类固醇激素信号作为一个关键的开关之间的发展途径，导致替代成人表型。然而，这种开关和环境敏感的GRNs之间的机制关系是未知的，这些GRNs的进化起源和动力学也是未知的，我们将通过实验室实验和计算分析各种Bicyclus物种野生种群的序列数据，研究可塑性的发展，进化和基因组学。具体来说，我们将（i）测试蜕皮激素，保幼激素和胰岛素信号在组织中的作用和可塑性的阶段特异性，（ii）识别和鉴定与发育可塑性相关的不同基因和GRNs，并在不同物种之间进行比较，以找到可塑性的起源，和（iii）通过与非-将从非洲（肯尼亚、喀麦隆、南非和加纳）的野生种群中收集不同种类的Bicyclus蝴蝶，并将在跨越季节性环境范围的受控条件下进行实验室饲养，以产生季节性表型，包括旱季、雨季和中间形式。这些数据沿着阶段特异性（幼虫和蛹）激素滴定实验（涉及蜕皮类固醇激素，保幼激素和胰岛素）在不同的季节条件下将相关的环境线索与表型和激素信号。此外，特定阶段的激素水平操纵实验将破译其在发育可塑性中的作用。这些实验室饲养（受控条件和激素操纵）个体的比较RNA seq转录组分析将鉴定与激素信号传导相关的基因和调控途径。这些数据沿着不同Bicyclus物种的全基因组测序数据将被用于基因组方法中，以形成祖先状态重建并识别与可塑性的起源和进化相关的趋同基因组变化。

This project investigates how African butterflies tune their morphology, behaviour and lifecycle to varying environmental conditions. This phenomenon is called phenotypic plasticity and is accomplished via tightly regulated developmental and regulatory cascades. It has evolved in many organisms across the globe as almost all environments show variability, in particular between seasons.While we have a good understanding of the ecological relevance, we only have a rudimentary mechanistic understanding of plasticity. What are the genes and pathways that sense the environment and produce a different phenotype when the environment changes? How do these genes interact in gene regulatory networks (GRNs)? How have these GRNs evolved when species invade new habitats or are faced with environmental changes? How does plasticity affect future adaptation, for instance to climate changes?To fill this gap, we use an established system that combines ecological relevance, experimental tractability and genomic resources-African Bicyclus butterflies. These species have repeatedly evolved plasticity in wing pattern, behaviour and life cycle upon invasions of seasonal savannahs from forests. Laboratory experiments have revealed Ecdysteroid hormone signalling as a key switch between developmental pathways leading to alternative adult phenotypes. However, the mechanistic relationship between this switch and environment-sensitive GRNs is unknown, as are theevolutionary origin and dynamics of these GRNs.With lab experiments and computational analyses of sequence data from wild populations of various Bicyclus species, we will study the development, evolution and genomics of plasticity. Specifically, we will (i) test the role of ecdysteroid hormone, juvenile hormone and insulin signalling in tissue and stage-specificity of plasticity, (ii) identify and characterise different genes and GRNs associated with developmental plasticity and compare these across species to find the origin of plasticity, and (iii) infer the repeated evolution and convergent genomic changes of plasticity GRNs by comparisons with conserved processes in non-plastic ancestor species.Different species of Bicyclus butterflies will be collected from wild populations in Africa ( Kenya, Cameroon, South Africa and Ghana) and will be lab-reared in controlled conditions spanning the range of seasonal environments to produce seasonal phenotypes including dry season, wet season and intermediate forms. These data along with stage-specific (larva and pupa) hormone titration experiments (involving ecdysteroid hormone, juvenile hormone and insulin) on different seasonal conditions will correlate the environmental cues associated with the phenotype and the hormone signalling. Further, stage-specific hormone level manipulation experiments will decipher their roles in developmental plasticity. Comparative RNA seq transcriptome analysis of these lab-reared (controlled condition and hormone manipulated) individuals will identify the genes and regulatory pathways correlated with the hormone signalling. These data along with whole-genome sequencing data of different Bicyclus species will be used in phylogenomic approaches to form an ancestral state reconstruction and identify convergent genomic changes associated with the origin and evolution of plasticity.