Determining the genetic basis of sexual conflict in Drosophila melanogaster: the role of the sex peptide.

确定果蝇性冲突的遗传基础：性肽的作用。

• 批准号: NE/C510516/1
• 负责人: Tracey Chapman
• 金额: $ 38.39万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FC510516%2F1
• 关键词: Determining; genetic; basis; sexual; conflict

Sexual conflict is a revolutionary way of viewing what happens between males and females over reproductive decisions. Rather than co-operating over who to mate with, how often to mate, how many offspring to produce and how much parental care to give, the sexes instead often disagree, and try to exploit one another for their own ends. Examples of this 'sexual conflict' have been described in many different organisms, but have been most intensively studied in the insects. In the fruitfly Drosophila melanogaster, there is strong conflict between the sexes over how often to mate. A high frequency of mating best suits males, as they provide no parental care and thus each extra mating results in them fathering more offspring. The interests of females are best served by a lower frequency of mating - they have a limited number of eggs to lay and beyond a certain level of remating, they gain no further increases in offspring numbers, Furthermore, high frequencies of mating are costly to females, shortening their lifespans and lowering their overall lifetime reproduction. Our previous work has revealed that these 'mating costs' in females are caused by the actions of molecules in the male semen, which are transferred to females during mating. We have recently identified a substance known as the 'sex peptide' which is responsible for the female mating costs, and matings with males that lack this peptide are 'cost-free' for females. Males benefit from the transfer of the sex peptide because one of its functions is to render females temporarily unwilling to mate again, hence males who transfer it father more offspring. The sex peptide therefore simultaneously harms females and benefits males and is the first gene product shown to underlie sexual conflict in any species. Our discovery prompts many questions: e.g. how does the SP harm females?, are females equally sensitive to it throughout their lives? and is the damage caused by the sex peptide permanent? We address these questions in the work proposed here. We have three broad aims and these are (1) to quantify the extent to which the sex peptide underlies sexual conflict, (2) to reveal how sex peptide exerts harm on females and (3) to measure how the costs and benefits of receiving the sex peptide are affected by mating rate and by variations in food supply. We will do large-scale experiments in the laboratory, using healthy flies. This will allow us to detect subtle differences and to estimate accurately 'fitness' (a combination of survival and reproductive output). To manipulate the level of sex peptide that females receive we will mate them to normal males or those which lack the sex peptide. The results will provide an in depth analysis, for the first time, of the basis of sexual conflict at the genetic level. The general benefits of the research will be to deepen our understanding of the evolution of sexual conflict, by understanding the nature and dynamics of the conflicts between males and females. This will allow us to better understand how reproductive strategies evolve in males and females. There are also wider potential applications in insect pest control. For example, in many parts of the world the true' fruit flies are pests. The females lay their eggs in ripe fruit, which is spoiled as the larvae develop. These pests are often controlled using the 'sterile insect technique' (SIT). In this, males are reared on a large scale in factories, sterilised and then released into the environment to mate with the wild females. Such matings are sterile and the pest population size is thus reduced. SIT works best if females do not mate again, and sex-peptide-like factors appear to play a crucial role in this. Hence manipulating the level of sex peptide-like factors could provide improvements in pest suppression in insects subjected to SIT.

性冲突是一种革命性的方式来看待男性和女性之间在生育决定上发生的事情。两性没有在交配对象、交配频率、生育多少后代以及给予父母多少照顾等问题上进行合作，而是经常意见不一，并试图为了各自的目的而相互剥削。这种“性冲突”的例子在许多不同的生物体中都有描述，但对昆虫的研究最为深入。在果蝇黑腹果蝇身上，两性之间在交配频率上存在着强烈的冲突。高频率的交配最适合雄性，因为它们不提供父母的照顾，因此每次额外的交配都会导致它们产生更多的后代。较低的交配频率最符合雌性的利益--它们要产卵的数量有限，超过了一定的交配水平，它们的后代数量就不会进一步增加，而且，高频率的交配对雌性来说代价高昂，缩短了它们的寿命，降低了它们的总寿命。我们之前的工作表明，雌性的这些“交配成本”是由雄性精液中的分子的作用引起的，在交配过程中，这些分子被转移到雌性身上。我们最近发现了一种被称为“性肽”的物质，它负责雌性交配的成本，而与缺乏性肽的雄性交配对雌性来说是“免费的”。雄性从性肽的转移中受益，因为它的功能之一是使雌性暂时不愿再次交配，因此雄性转移它的父亲的后代更多。因此，性肽同时伤害雌性和有益于雄性，是第一个被证明在任何物种中导致性别冲突的基因产物。我们的发现引发了许多问题：例如，SP如何伤害女性？女性在一生中对它同样敏感吗？性肽造成的损害是永久性的吗？我们在这里提出的工作中解决了这些问题。我们有三个广泛的目标，它们是(1)量化性肽在多大程度上导致性冲突，(2)揭示性肽如何对雌性造成伤害，以及(3)衡量交配率和食物供应变化如何影响接受性肽的成本和收益。我们将在实验室里用健康的苍蝇做大规模的实验。这将使我们能够发现细微的差异，并准确地估计“适合度”(存活率和生殖产出的组合)。为了操控女性所接受的性肽水平，我们会将她们与正常的男性或缺乏性肽的男性交配。研究结果将首次深入分析遗传层面上的性别冲突的基础。这项研究的总体好处将是通过理解男性和女性之间冲突的性质和动态，加深我们对性别冲突演变的理解。这将使我们更好地了解男性和女性的生殖策略是如何演变的。在病虫害防治方面也有更广泛的潜在应用。例如，在世界上许多地方，真正的“果蝇”是害虫。雌性在成熟的果实中产卵，随着幼虫的发育，成熟的果实会被破坏。这些害虫通常是通过“昆虫不育技术”(SIT)来控制的。在这种情况下，雄性在工厂里大规模饲养，进行绝育，然后释放到环境中与野生雌性交配。这样的交配是不育的，因此害虫种群数量减少了。如果雌性不再交配，SIT效果最好，性肽类因素似乎在其中发挥了关键作用。因此，控制性肽样因子的水平可以改善对受SIT影响的昆虫的害虫抑制。

项目成果

Exposure to rivals and plastic responses to sperm competition in Drosophila melanogaster

• DOI: 10.1093/beheco/arp189
• 发表时间: 2010-03-01
• 期刊: BEHAVIORAL ECOLOGY
• 影响因子: 2.4
• 作者: Bretman, Amanda;Fricke, Claudia;Chapman, Tracey
• 通讯作者: Chapman, Tracey