Dissertation Research: Reaction Norms of Ontogenetic Trajectories in Lobelia

个体发生和遗传变异是两个被认为对我们理解进化变化的模式和过程至关重要的主题。虽然研究发育系统和基因型规范对环境的反应的基本概念在本世纪上半叶已经形成，但直到最近它们才成为实验和理论工作的中心焦点。发育方面侧重于个体发生轨迹的概念，它描述了生长过程中表型的变化。环境变化引起基因型特异性反应，称为表型可塑性，它是通过基因型将环境和表型联系起来的功能来描述的：即反应规范。本研究的目的是结合发育和环境因素对两种半边莲（半边莲科）的遗传变异进行研究。该研究项目分为两个不同的实验：(I)实验一是描述个体发生轨迹对不同遮光水平的可塑性，每个物种的两个种群的基因型样本。目的是获得以下信息：1)发育过程中反应规范的遗传变异；2)环境变化如何改变发育轨迹。（二）实验二为人工选择实验，在实验一的基础上，考察半边莲属植物的遗传系统对其反应规范的加性遗传方差的响应能力。这类研究的近期目标是利用实际实验中的一些参数值获得可靠的表型进化模型。在这个意义上的尝试已经发表，但只关注变异的个体发生成分。我们需要一个更全面的模型，其中包括环境变化，并与我们对生物复杂性的一般理解和实际实验的可能性相一致。最终目标是获得对表型新颖性在宏观进化过程中产生和最终固定的方式的基本理解和一般现象学描述。这些概念，加上我们对这些现象的生理和分子基础知识的平行增长，最终将使我们对如何将种群生物学和分子遗传学结合起来以更全面地理解进化现象有更明确的认识。

Ontogeny and genetic variation are two topics that are thought to be crucial for our understanding of patterns and processes of evolutionary change. Although the basic concepts for the study of developmental systems and the reaction of norms of genotypes to the environments had been formulated during the first half of this century, only recently have they become a central focus of experimental and theoretical work. The developmental aspect focuses on the concept of ontogenetic trajectories, which describes the change in phenotype during growth. The environmental variation, which elicits a genotype-specific response called phenotypic plasticity, is described by a function that relates environments and phenotypes through the genotype: i.e., the reaction norm. The aim of this proposal is to couple the developmental and environmental aspects in a study of genetic variability in two species, Lobelia cardinalis and Lobelia siphilitica (Lobeliaceae). The research project is divided into two distinct experiments: (I) Experiment I is a description of the plasticity for ontogenetic trajectories to different level of shading in the genotypes samples from two populations for each species. The objective is to gain information about 1) genetic variation for reaction norms across development and 2) how environmental changes can modify the developmental trajectory. (II) Experiment II is an artificial selection experiment which - based on the information obtained from Experiment I - will test the ability of the genetic systems of Lobelia spp. to respond to selection on additive genetic variance of their reaction norms. A proximal objective of this type of research is to obtain reliable models of phenotypic evolution, using some of the parameter values from actual experiments. Attempts in this sense have already been published, but focused only on the ontogenetic component of variation. A more comprehensive model is desirable, which includes environmental variation and is consistent with our general understanding of biological complexity and with actual experimental possibilities. The ultimate goal is to gain a basic understanding and a general phenomenological description of the ways in which phenotypic novelties can arise and eventually be fixed during macroevolution. These notions, together with the parallel increase in our knowledge of the physiological and molecular basis of such phenomena, would eventually lead us to less vague statements about how population biology and molecular genetics can be coupled for a more complete understanding of evolutionary phenomena.