Mechanisms of Life History Evolution in an Ancient Vertebrate

古代脊椎动物生命史进化的机制

• 批准号: RGPIN-2019-06653
• 负责人: Docker, Margaret
• 金额: $ 2.91万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739029
• 关键词: Mechanisms; Life; History; Evolution; Ancient

`Survival of the fittest' refers to the idea that, in nature, there is competition to survive and reproduce. In addition to morphological and physiological traits, an organism's fitness is affected by life history traits (e.g., age and size at maturity, lifespan, number of offspring). Life history traits show tremendous variation among individuals, environments, and species, and much research has been devoted to understanding the trade-offs and fitness consequences of these traits. They are very important, for example, in predicting the effect of human-induced changes in age- or size-specific mortality rates in species of management concern. Recent advances in genomics are now facilitating important research into the genetic mechanisms underlying these traits. Lampreys, ancient vertebrates occurring at one of the key branch points in the tree of life, are excellent models to study life history evolution. Living lampreys have a highly conserved body plan, looking very much like fossil lampreys from 360 million years ago, but they exhibit a diversity of life history types. All lampreys filter feed on microscopic organisms during a prolonged larval stage in fresh water but, following metamorphosis, they diverge into different adult feeding and migratory types. In non-parasitic forms, which remain protected within their natal streams and become sexually mature without further feeding, adult mortality rates are low but their small body size limits the number of eggs produced. Parasitic forms delay sexual maturation and migrate to sea or large lakes to feed on other fishes; growth and fecundity are much higher in these forms, but so is mortality. Non-parasitic forms have evolved from parasitic forms, and many of these species are of conservation concern. Conversely, the parasitic sea lamprey in the Atlantic Ocean has given rise to a freshwater form in the Great Lakes, and it is a significant pest causing billions of dollars of damage to the commercial fishery. My proposed research seeks to identify the genetic basis of feeding and migratory type in lampreys by investigating: 1) whether gonadal development during the larval stage `predetermines' adult life history type; 2) which genes are `turned on' or `turned off' at the key developmental branch points when the feeding and migratory types diverge; and 3) ways in which the genome of the Great Lakes sea lamprey has diverged from the ancestral Atlantic population since colonization. This research has conservation and management implications (e.g., to be able to predict the potential for lampreys to become invasive in other freshwater systems), and will further enhance Canada's reputation on life history evolution in fishes. It will also provide at least 12 students with technical training in cutting-edge technologies (e.g., next-generation sequencing) and analysis of large genomic datasets, thus producing personnel highly qualified for employment in research and development in academia and industry.

“适者生存”是指自然界存在着生存和繁殖的竞争。除了形态和生理特征之外，生物体的适应性还受到生活史特征的影响（例如，年龄和成熟时的大小，寿命，后代的数量）。生活史特征在个体、环境和物种之间表现出巨大的差异，许多研究致力于了解这些特征的权衡和适应性后果。例如，它们在预测人类引起的变化对管理关注物种的特定年龄或体型死亡率的影响方面非常重要。基因组学的最新进展正在促进对这些特征背后的遗传机制的重要研究。七鳃鳗是古脊椎动物中的一个重要分支，是研究生活史演化的极好模式动物。活的七鳃鳗有一个高度保守的身体计划，看起来非常像3.6亿年前的化石七鳃鳗，但它们表现出生活史类型的多样性。所有的七鳃鳗过滤器饲料微生物在淡水中的幼虫阶段，但在变态后，他们分化成不同的成年人喂养和迁移类型。在非寄生形式中，它们在其纳塔尔溪流中受到保护，并且在没有进一步喂养的情况下变得性成熟，成年死亡率很低，但它们的小体型限制了产卵的数量。寄生形式延迟性成熟并迁移到海洋或大湖中以其他鱼类为食;这些形式的生长和繁殖力要高得多，但死亡率也高得多。非寄生形式是从寄生形式进化而来的，其中许多物种是保护问题。相反，大西洋中的寄生海七鳃鳗在五大湖中产生了淡水形式，它是一种重要的害虫，对商业渔业造成了数十亿美元的损失。 本研究拟通过以下研究来确定七鳃鳗摄食和洄游类型的遗传基础：1）幼虫期性腺发育是否“预先决定”成年生活史类型; 2）当摄食和洄游类型发生分化时，在关键发育分支点哪些基因被“开启”或“关闭”; 3）自殖民化以来，五大湖七鳃鳗的基因组与祖先大西洋种群的差异。这项研究具有保护和管理意义（例如，这将有助于预测七鳃鳗入侵其他淡水系统的可能性），并将进一步提高加拿大在鱼类生活史进化方面的声誉。它还将为至少12名学生提供尖端技术方面的技术培训（例如，下一代测序）和大型基因组数据集的分析，从而培养出高素质的人才，在学术界和工业界从事研究和开发工作。