Natural and sexual selection linkages across the biphasic life cycle: experimental insight from fish

整个双相生命周期中的自然选择和性选择联系：来自鱼类的实验见解

• 批准号: RGPIN-2022-03789
• 负责人: Purchase, Craig
• 金额: $ 2.04万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745856
• 关键词: Natural; sexual; selection; linkages; across

Animals have biphasic life cycles that alternate between diploid (adult=2 chromosome copies) and haploid (gametes=1 copy) phases. Across this cycle, selection can be conceptualized at four stages: natural and sexual selection in the diploid phase, natural and sexual selection in the haploid phase. These stages are the main drivers of evolution - eg, a male bird that does not survive to adulthood (1), or survives but does not acquire a mate (2), contributes no gametes to selection in the haploid phase, and no direct descendants in the next generation. He also leaves no descendants if he does mate but his sperm are incapable of fertilizing an egg (3) or winning paternity under sperm competition (4). The stages are usually studied independently, but selection stages on traits expressed during the diploid and haploid phases are interconnected. Improved knowledge of the connected opportunities for selection within biphasic life cycles enables clearer insights into ecological and evolutionary processes, with benefits to applied science. In that context, my research focuses on events leading up to and following the haploid phase. Using external fertilizing fish, we examine the interactions between male and female gametes experiencing both sexual and natural selection in the fertilization micro-environment. The long-term goal is to determine how selection connections associated with the haploid phase, influence fertilization and development in two study systems. Progress will be achieved from 3 short-term objectives: (1) How do diploid (adult) experiences influence sexual selection in the haploid phase (among gametes)? This objective fills key knowledge voids in my study systems with capelin and hybridizing salmon/trout. It will determine whether pre- and post-mating sexual selection complement each other, and if poor diploid diet reduces the ability of sexual selection in the haploid phase to reduce hybridization. (2) Can constraints imposed by natural selection impact the outcome of sexual selection in the haploid phase? Within the diploid phase, the trade-off between natural and sexual selection is well known, such as the `inconvenience' of elaborate male bird tail feathers to survival. However, within the haploid phase it is not. We have virtually no understanding of when and how natural selection modifies the outcomes of sexual selection among gametes. We will determine how the scope for female biasing of sperm competition (cryptic female choice) is impacted by natural selection constraints. (3) How do haploid (gamete) experiences influence natural selection in the diploid phase (development of offspring)? This can occur if for example there are epigenetic changes to individual gametes that affect embryos. While keeping the same father, targeted work will show how sperm exposure to either stressful salinity (capelin) or river acidification (salmon), or rival male seminal fluid under sperm competition, impact subsequent offspring development.

动物具有在二倍体（成体=2个染色体拷贝）和单倍体（配子=1个拷贝）阶段之间交替的双相生命周期。在这个周期中，选择可以被概念化为四个阶段：二倍体阶段的自然选择和性选择，单倍体阶段的自然选择和性选择。这些阶段是进化的主要驱动力-例如，雄性鸟类不能存活到成年（1），或者存活但没有获得配偶（2），在单倍体阶段没有配子选择，并且在下一代没有直接后代。如果他确实交配了，他也不会留下后代，但他的精子不能受精卵（3）或在精子竞争中赢得父权（4）。这些阶段通常是独立研究的，但在二倍体和单倍体阶段表达的性状的选择阶段是相互关联的。对双相生命周期中相互关联的选择机会的了解的提高，使人们能够更清楚地了解生态和进化过程，这对应用科学有利。在这种情况下，我的研究重点是事件导致和以下的单倍体阶段。使用外部的鱼，我们研究了在受精微环境中经历性选择和自然选择的雄性和雌性配子之间的相互作用。长期的目标是确定选择与单倍体阶段，影响受精和发育的两个研究系统中的连接。从3个短期目标取得进展：（1）二倍体（成年）经历如何影响单倍体阶段（配子间）的性选择？这个目标填补了我的研究系统与毛鳞鱼和杂交鲑鱼/鳟鱼的关键知识空白。它将确定交配前和交配后的性选择是否相互补充，以及如果较差的二倍体饮食降低了单倍体阶段的性选择能力，从而减少杂交。(2)自然选择施加的限制会影响单倍体阶段性选择的结果吗？在二倍体阶段，自然选择和性选择之间的权衡是众所周知的，例如精心制作的雄鸟尾羽对生存的“不便”。然而，在单倍体阶段，它不是。对于自然选择何时以及如何改变配子间性选择的结果，我们几乎一无所知。我们将确定精子竞争的女性偏好（神秘的女性选择）的范围如何受到自然选择约束的影响。(3)单倍体（配子）经历如何影响二倍体阶段（后代的发育）的自然选择？例如，如果单个配子发生影响胚胎的表观遗传变化，就会发生这种情况。在保持同一个父亲的同时，有针对性的工作将显示精子暴露于压力盐度（毛鳞鱼）或河流酸化（鲑鱼），或精子竞争下的竞争性男性精液，如何影响随后的后代发育。