Exploring the `Harperian' paradox: Leaving descendants in a crowded plant world

邻国之间的竞争通常是 被认为是自然选择中最强烈的力量之一， 植物功能性状的进化和多样性。大部分 传统的资源条件下植物成功进化策略理论 限制（竞争能力）是基于规模优势的假设， 优势通常涉及在摄取/消耗 有争议的资源，因此通常与更大的增长有关 最大潜在体型（MAX）。我最近的研究 然而，它指出了另一种解释， 经济优势假说，其中生殖成功严重 拥挤的社区通常更大，而不是具有较大MAX的物种， 但对于具有较高生殖力分配的物种，即产生较大的 每单位的后代数（有性或无性繁殖） 每单位时间的单位母株大小。本文提出的研究将使用温室 研究、自然植被实地试验和大规模普查 加拿大安大略东部地区植物群的调查，以确定主要的 生殖力分配的组成部分，因此也是生殖经济的能力 在开花植物中。重点将放在濒危物种和植被上 与农业边际土地的生态系统服务有关的（如老 fields）。主要的预测是，高繁殖力的分配是促进 四个可能的大小度量：（i）相对小的MIN（最小阈值 亲本的身体大小产生种子或克隆后代）;（ii）相对 高地上体重密度（每单位物理量的干重） 空间占用）;（iii）相对小的种子尺寸，即所有 在其他条件相同的情况下，一种产生较小种子的植物， 单位植物体大小;和（iv）相对小的叶大小，即 一种植物，使较小的叶子可以使更多的叶子为一个给定的身体大小， 支持营养组织（更高的叶强度），这使得 更大的腋芽库（每单位体型）可用于部署， 克隆和/或有性生殖分生组织。我们可以预测，拥有更大的芽库也意味着更多的分生组织 可用于战略部署， 建筑/生长形式的可塑性（例如，在可变的光照条件下的分支强度），或作为 一种储备，用于在食草动物失去组织后的生存和补偿 或干扰。 这些项目，在五年内，将涉及培训2名博士生，4-5名硕士生和10名本科论文学生，平均每年有3-4名研究生和2名理学士（荣誉）论文学生/暑期学生技术人员在我的实验室工作。

Competition between near neighbours is conventionally regarded as one of the most intense forces of natural selection that has shaped the evolution and diversity of functional traits in plants. Most of the traditional theory for evolved strategies of success in plants under resource limitation (competitive ability) is based on a Size Advantage' hypothesis, where superiority involves generally greater success in uptake/depletion of contested resources, typically associated therefore with greater growth accumulation and larger maximum potential body size (MAX). My recent research however points to an alternative interpretation involving a Reproductive Economy Advantage' hypothesis, where reproductive success within severely crowded neighbourhoods is generally greater, not for species with larger MAX, but for species with higher fecundity allocation', i.e. production of a larger number of offspring (sexual or clonal) per unit parent plant size per unit time. The research proposed here will use greenhouse studies, field experiments in natural vegetation, and large scale census surveys of the regional flora in eastern Ontario, Canada to identify the major components of fecundity allocation and hence capacity for reproductive economy in flowering plants. Emphasis will be placed on species at risk and vegetation associated with ecosystem services of marginal lands for agriculture (e.g. old fields). The main predictions are that high fecundity allocation is promoted by four potential size metrics: (i) relatively small MIN (minimum threshold parental body size for producing seed or clonal offspring); (ii) relatively high above-ground body mass density (dry mass per unit of physical space occupancy); (iii) relatively small seed size i.e. all else being equal, a plant that makes smaller seeds, can make more of them per unit plant body size; and (iv) relatively small leaf size i.e. a plant that makes smaller leaves can make more leaves for a given body size of supporting vegetative tissue (a higher leafing intensity'), which enables a larger axillary bud bank' (per unit body size) available for deployment as clonal and/or sexual reproductive meristems. Having a larger bud bank, we can predict, also means that more meristems are available for strategic deployment in the expression of architectural/growth-form plasticity (e.g. for branching intensity under variable light regimes), or as a reserve' for survival and compensation following tissue loss to herbivores or disturbance. These projects, over five years, will involve training for 2 PhD students, 4-5 MSc students, and 10 undergraduate thesis students with an average of 3-4 graduate students and 2 BSc (Hons) thesis students / summer student technicians working in my lab each year.