DISSERTATION RESEARCH: The Phenotypic and Genetic Basis of Facilitation and Competition in Plants

当没有足够的营养和阳光等资源时，生长在同一个地方的植物会互相伤害。这就意味着弱小的竞争者只能任由上级竞争者摆布，生存和繁殖的可能性也就更小。另一方面，植物在面临干旱等环境压力时实际上可以相互保护。通过阻挡阳光到达并加热土壤，生长在一起的植物可以防止土壤水分的蒸发。但由于环境不断变化，一株植物在其一生中既会受到伤害，也会受到邻居的保护。这些动态的邻居关系提出了许多有趣的问题。是什么让一些植物成为很好的竞争者，而另一些植物却依赖于邻居的保护？遗传与环境（先天与后天）在多大程度上控制了植物是互相伤害还是互相保护？伤害和保护会导致植物性状的进化吗？研究人员的目标是确定环境条件，植物性状和导致伤害和保护的基因，并利用这些信息来确定这些植物相互作用是否影响进化。通过确定减少危害的条件，这项研究有助于生态学家开发更好的方法来保护濒危物种。这些结果也可以用来培育即使在资源匮乏和压力很大的情况下也能生存和生产食物的作物。研究人员将环境操纵与选择分析和其他定量遗传学技术（例如性状协方差分析）相结合，将竞争（伤害）和促进（保护）与拟南芥（拟南芥科）的自然选择和适应联系起来。邻居引起的光、湿度和温度的变化与这些邻居对焦点植物生存和繁殖的影响有关。全基因组关联图谱被用来确定竞争和促进基因，这些基因解释了在存在与不存在邻居的情况下生存和繁殖的差异。一旦所有这些分析完成，研究人员计划利用先前对基因功能的了解来检验这一假设，即控制营养加工和需求、物候和胁迫耐受性的基因也控制竞争和促进作用。

Plants growing in the same place harm each other when there are not enough resources such as nutrients and sunlight to go around. This means poor competitors are at the mercy of superior ones, and less likely to survive and reproduce. On the flip side, plants can actually protect each other when faced with environmental stress such as drought. By blocking sunlight from reaching and heating the soil, plants that are growing close together prevent the evaporation of soil moisture. But since environments are constantly changing, a single plant can receive both harm and protection from neighbors over its lifetime. These dynamic neighbor relationships raise many intriguing questions. What makes some plants good competitors, but makes others rely on protection from their neighbors? How much do genetics versus the environment (nature versus nurture) control whether plants will harm or protect each other? Do harm and protection cause plant traits to evolve? The researchers aim to identify environmental conditions, plant traits, and genes that cause harm and protection, and use this information to determine if these plant interactions affect evolution. By identifying conditions that reduce harm, this research helps ecologists working to develop better methods to protect endangered species that are poor competitors. The results also can be used to breed crops that can survive and make food even when resources are low and stress is high. The researchers are combining manipulations of the environment with selection analysis and other quantitative genetics techniques (e.g. analyses of trait co-variances) to connect competition (harm) and facilitation (protection) with natural selection and adaptation in Arabidopsis thaliana (Brassicaceae). Changes in light, moisture, and temperature caused by neighbors are being linked with the effects of those neighbors on the survival and reproduction of focal plants. Genome-wide association mapping is being used to identify genes for competition and facilitation as those explaining differences in survival and reproduction in the presence versus absence of neighbors. Once all these analyses are complete, the researchers plan to use previous knowledge of gene function to test the hypothesis that genes controlling nutrient processing and requirements, phenology, and stress tolerance also control competition and facilitation.