Quantifying fitness benefits of polyandry in Atlantic salmon

量化大西洋鲑鱼一妻多夫的健康益处

• 批准号: NE/I015523/1
• 负责人: Matthew Gage
• 金额: $ 6.75万
• 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: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI015523%2F1
• 关键词: Quantifying; fitness; benefits; polyandry; Atlantic; Quantifying; fitness; benefits; polyandry; Atlantic

Why do females of so many species mate with multiple males, when they gain nothing from this 'polyandry' apart from spermatozoa, and mating with only one male is sufficient to ensure full fertility? This remains an enduring question in evolutionary biology, because significant costs have been measured for females when they multiply mate. We now know that the mechanisms operating at the gamete level between mating and fertilization are much more complex than previously supposed. Under polyandry, with bigger and more diverse populations of spermatozoa competing for fertilization, there is even more selective opportunity for adaptations that promote sperm competitive ability, and / or cryptic female choice. Recent experimental research suggests that polyandry allows females to 'capture' genetic benefits at the gamete level for their resulting offspring. Such benefits may arise because of links between sperm quality and general fitness, or because females have evolved mechanisms that allow selection of sperm that carry intrinsically superior genes or undamaged DNA, or there may be cryptic choice for sperm that carry genes that are more compatibile to the female/egg genotype. We propose to quantify benefits of polyandry in a system using carefully controlled in vitro fertilizations to create offspring batches from the same female that only differ according to whether they were fertilized by five separate males singly, or by the same five males but in simultaneous sperm competition. Our experimental model will be the Atlantic salmon, in which females naturally mate with up to 16 males at once, and where external fertilization allows us to conduct in vitro fertilizations that control or eliminate a number of important confounding effects on offspring fitness, such as biased or variable maternal investment in egg quality. Our previous work on salmon in vitro fertilization dynamics will allow us to ensure that fertility is not a limiting factor for each egg batch. For each female, we will create 5 egg batches which were fertilized by sperm from 5 different, single males (=monandrous condition), and 5 egg batches that were fertilized by homogenised mixes of sperm from the same 5 males (= polyandry condition). These paired comparisons will be repeated 25 times, using 25 females and 125 males. The design will control for adult identity and egg effects, and generate offspring batches that only differ according to fertilization in the presence or absence of sperm competition and/or egg choice. After fertilization, the offspring batches will be measured for survival and growth across key stages of embryo development, egg hatch, alevin development, fry emergence, and parr survival, success and growth. These fitness measures will all be conducted in experimental stream sections that allow environmentally-relevant selection to operate. Use of the Ims salmon field station in Norway will provide access to facilities that enable experimental control, while rearing eggs and fry in semi-natural conditions with selection from many of the normal forces that operate on salmon eggs, embryos, fry and parr. It is essential that we measure egg and offspring perfomance under conditions that present some selection from the natural environment, because this is where fitness benefits will be most important. At the conclusion of the project, we will have measured what fitness benefits can be gained under polyandry, and what life stages these gains occur in salmon. The results will be of central importance to a pure understanding of the genetic benefits of polyandry. Importantly, our work will have applied relevance for salmon hatchery breeding strategies. To conserve genetic diversity, hatchery protocols now use enforced monogamy to maximize the number of male breeders involved in reproduction. However, there may be important polyandry benefits that are excluded by these protocols, and our project will measure how important these benefits might be.

为什么这么多物种与多个雄性的雌性相吻合，而这些雌性除了精子以外的“一夫多妻制”，而与只有一个雄性的交配足以确保完全生育能力？这仍然是进化生物学中的一个持久问题，因为在女性繁殖时已经衡量了巨大的成本。我们现在知道，在交配和受精之间在配子级别运行的机制比以前想象的要复杂得多。在一夫多妻制的领导下，具有更大和更多样化的精子竞争竞争受精的人数，有更多选择性的适应机会，可以促进精子竞争能力和 /或神秘的女性选择。最近的实验研究表明，一夫多妻制允许女性在配子水平上“捕获”其后代的遗传益处。由于精子质量与一般健身之间的联系，可能会产生这种好处，或者是由于女性具有进化的机制，可以选择具有本质上具有优势基因或未损坏的DNA的精子，或者对于携带与女性/蛋白蛋白型更兼容的精子可能有隐秘的选择。我们建议使用经过精心控制的体外肥料来量化一夫多夫的好处，以从同一位雌性中产生后代批次，而这些后代批次仅根据五个单独的雄性或同一五个男性，但同时精子竞争而受到五个单独的雄性的施肥。我们的实验模型将是大西洋鲑鱼，其中女性自然会同时与多达16位男性交配，外部施肥使我们能够进行体外施肥，以控制或消除对后代适应性的许多重要混杂作用，例如偏见或可变的母体对鸡蛋质量的产妇投资。我们以前在体外受精动力学方面的工作将使我们能够确保生育能力不是每个鸡蛋批次的限制因素。对于每位雌性，我们将创建5个鸡蛋批次，这些鸡蛋受到来自5种不同的单一男性（=单鼠疾病）的精子的施肥，以及5个鸡蛋批次，这些鸡蛋批次被同一5雄性的精子均质混合物（=多养生条件）施肥。这些配对的比较将使用25个女性和125名男性重复25次。该设计将控制成人身份和鸡蛋效应，并产生后代批次，这些批次仅在存在或不存在精子竞争和/或鸡蛋的情况下根据受精而有所不同。受精后，将测量后代批次的生存和生长，跨越胚胎发育，鸡蛋孵化，Alevin发育，炸鸡出现以及PARR存活，成功和成长的关键阶段。这些适应性度量将全部在实验流部分中进行，以使环境相关的选择可以运行。在挪威的IMS鲑鱼现场站的使用将提供对实验控制的设施，同时在半自然条件下饲养鸡蛋并在许多正常力量中选择在鲑鱼鸡蛋，胚胎，炸薯条，炸和Parr的情况下进行选择。在提供自然环境中一些选择的条件下，我们必须测量鸡蛋和后代的性能，因为这是健身益处最重要的地方。在项目结束时，我们将衡量在一夫多妻制下可以获得哪些适应性益处，以及在鲑鱼中发生的生命阶段。结果对于纯粹理解多遵守的遗传益处至关重要。重要的是，我们的工作将应用于鲑鱼孵化场育种策略。为了保护遗传多样性，孵化场方案现在使用强制性一夫一妻制来最大化涉及繁殖的男性育种者的数量。但是，这些协议排除了重要的一致性好处，我们的项目将衡量这些好处的重要性。