Male-killing symbiosis across a predator-prey interaction: a genomic and experimental approach

捕食者与猎物相互作用中的雄性致死共生：基因组和实验方法

• 批准号: NE/X010171/1
• 负责人: Ailsa McLean
• 金额: $ 9.73万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX010171%2F1
• 关键词: Male; killing; symbiosis; across; predator

Most insects carry specialised bacteria that dwell permanently inside them. These bacteria are known as symbionts and may be beneficial or costly to their insect host. In this project, we will investigate a bacterial symbiont, Spiroplasma, that is able to manipulate host insect reproduction to its own advantage.Like many insect symbionts, Spiroplasma is predominantly transmitted from female insects to their offspring. Because males cannot transmit the bacteria, they are essentially an evolutionary 'dead end' from the perspective of the symbiont. Symbionts are therefore under selection to increase the proportion of female offspring, and the result is a diversity of symbiont-induced reproductive manipulation strategies. Spiroplasma employs one of the most straightforward: male offspring carrying the symbiont die before adulthood (usually in the egg stage). This is assumed to benefit the surviving sisters, although the advantages are not always clear.In addition to maternal transmission, symbionts can occasionally be transmitted between unrelated individuals, either within or between species. This 'horizontal' transmission is evolutionarily important because it is a route for heritable characteristics to be passed across species boundaries in animals. However, since such transfers are rare in nature, we know little about the process. In this project, we will study two closely-related groups of Spiroplasma, infecting ladybirds and aphids respectively, in order to ask what happens when symbionts move between distantly-related insects.First, we will sequence the genomes of 13 strains of Spiroplasma bacteria: three from different species of ladybirds, and 10 from the pea aphid. The pea aphid strains will include bacteria causing complete, partial and no death of male offspring. We will use the genomes to look for similarities and differences among the Spiroplasma strains in the putative genetic mechanism for male-killing. We also aim to identify the genetic variation that drives the phenotypic differences in male-killing seen among the aphid Spiroplasma. In the second part of the project, we will recreate a likely route of symbiont transmission. Ladybirds are well-known as predators of aphids, and it is highly plausible that this predator-prey relationship allowed transmission of Spiroplasma between the two groups in their evolutionary past. We will carry out microinjection of body fluid containing male-killing Spiroplasma from aphids to ladybirds, and vice versa. We will test whether a new heritable infection is established and if the new infections cause male-killing. Our study combines an ambitious plan to recreate cross-species symbiont transmission with a detailed understanding of mechanism through symbiont genome sequencing. Ladybirds and aphids present a great opportunity to understand horizontal acquisition of traits via horizontal transmission of symbionts, and also to investigate the barriers that may stand in the way of that transfer. By gaining a full picture of symbiont function and transmission in the context of one specific predator-prey interaction, we will open the way to answer further questions surrounding the acquisition of novel symbionts, and the evolution of symbiont-mediated effects. Insects are an extraordinary evolutionary success story. Hidden inside insects, bacterial symbionts play important roles in nutrition, defence and reproduction. Explaining how and why new symbiotic associations arise is therefore a vital element for understanding insect evolution, and is the overarching aim of the project we propose.

大多数昆虫都携带专门的细菌，这些细菌居住在其中。这些细菌被称为共生体，对其昆虫宿主可能是有益的或昂贵的。在这个项目中，我们将研究一个细菌共生体，螺旋体，能够操纵宿主的昆虫繁殖以自身的优势。就像许多昆虫共生体一样，螺旋体主要从雌性昆虫传播到其后代。由于雄性无法传播细菌，因此从共生体的角度来看，它们本质上是进化的“死胡同”。因此，共生体正在选择以增加女性后代的比例，其结果是共生体诱导的生殖操纵策略的多样性。 Spiroplasma采用了最直接的：雄性后代在成年前（通常在鸡蛋阶段）。尽管优势并不总是很明显，但假定这可以使尚存姐妹受益。除了母亲的传播外，偶尔可以在物种之间或物种之间无关的个体之间传播共生体。这种“水平”传播在进化上很重要，因为它是跨动物中物种边界传递的可遗传特征的途径。但是，由于这种转移本质上很少见，因此我们对这一过程一无所知。在这个项目中，我们将分别研究两组与密切相关的螺旋形群，分别感染瓢虫和蚜虫，以询问当Symbionts在遥远的昆虫之间移动时会发生什么，我们将对13种螺旋藻细菌的基因组进行测序：三种螺旋藻的基因组：来自不同种类的Ladybirdbidybidybidybidybidybidebirdbybybybys peal and 10。豌豆蚜虫菌株将包括造成雄性后代的完整，部分和无死亡的细菌。我们将使用这些基因组在推定的遗传机制中寻找螺旋藻菌株之间的相似性和差异。我们还旨在确定驱动蚜虫螺旋藻中男性杀伤中表型差异的遗传变异。在项目的第二部分中，我们将重新创建Symbiont传输的可能途径。瓢虫众所周知是蚜虫的捕食者，这种捕食者捕食的关系使两组在进化的过去之间可以在两组之间传播螺旋形。我们将对从蚜虫到瓢虫的含有男性杀伤的螺旋体的体液进行显微注射，反之亦然。我们将测试是否建立了一种新的可遗传感染，以及新的感染是否引起男性杀伤。我们的研究结合了一个雄心勃勃的计划，即通过共生体基因组测序来重现跨物种共生体传播以及对机制的详细理解。瓢虫和蚜虫提供了一个很好的机会，可以通过水平传播的共生体传播来了解特征的水平收购，并研究可能阻碍这种转移的障碍。通过在一种特定的捕食者互动中获得共生函数和传播的全部图景，我们将开辟一个方法，以回答围绕新型共生体获得的进一步问题，以及共生体介导的效果的演变。昆虫是一个非凡的进化成功故事。隐藏在昆虫的内部，细菌共生体在营养，防御和繁殖中起着重要作用。因此，解释了如何以及为什么出现新的共生关联是理解昆虫进化的重要因素，并且是我们提出的项目的总体目的。