Dissertation Research: The Ecological Genetics of PhenotypicResponses to Three Light Environments in Collinsia verna

9701148雅罗斯兹大多数生物生活在多变的环境中。例如，几乎所有的植物在它们的一生中都会经历温度、光照、水分和营养的频繁的时间波动。直到最近，生物学家才开始研究这种环境异质性对自然选择的意义。一个普遍的预期是，环境的异质性将有利于表型为塑料的植物。一种适应性强的塑料植物表现出与它所处的环境条件相适应的表型。例如，一种生长在阴凉处的植物可能会长出又大又薄的叶子，以有效地收集有限的光线，而同样的植物在全日照下生长，可能会产生更小、更厚的叶子，以最大限度地减少水分损失。每一种叶片表型都使植株比表现出另一种表型的植株更适合，即产生更多的种子。尽管大多数性状的表型可塑性普遍存在，但表型变异在自然种群中的生态意义和适应性相关性很少被研究。PI将通过研究冬季一年生野花Collinsia Verna(蓝眼玛丽)自然种群中已知遗传关系的个体，来表征对三种光环境的表型反应的遗传基础。PIS将通过研究已知对不同光照水平作出反应和/或与适应性密切相关的性状(例如，萌发日期、越冬时的大小、叶片的大小和形状、植株的大小和分枝模式、第一次开花的日期、花数、种子数量和种子大小)来研究光诱导的表型变化的适合性后果。人类活动正在造成从当地栖息地碎片化到全球气候变化的各种规模的前所未有的环境变化，对地球的生物多样性产生深远的影响。这项研究的结果将有助于我们理解关于生物多样性及其管理的许多重要问题：物种范围的决定因素是什么？一个物种的压力环境是由什么构成的？个体和物种如何应对新的和不断变化的环境？什么时候才能合理地期望物种适应变化，而不是灭绝？通过评估表型对光的反应的适应性，以及通过量化塑料性状进一步变化的可能性，这项研究将对我们理解在不同或变化的环境中的自然选择做出重要贡献。

9701148 Jarosz Most organisms live in variable environments. For example, nearly all plants experience frequent temporal fluctuations in temperature, light, moisture, and nutrients during their lifetimes. Only recently have biologists begun to address the significance of this environmental heterogencity with regard to natural selection. A general expectation is that environmental heterogeneity will favor plants that are phenotypically plastic. An adaptively plastic plant expresses a phenotype appropriate for the environmental conditions in which it occurs. For example, a plant growing in shade might produce large thin leaves to efficiently harvest the limited light, while the same plant growing in full sun might produce smaller, thicker leaves to minimize water loss. Each leaf phenotype allows the plant to be more fit, i.e., to produce more seeds, than if the alternate phenotype were expressed. Despite the ubiquity of phenotypic plasticity of most traits, the ecological meaning and adaptive relevance of phenotypic variation in natural populations have seldom been investigated. The PIs will characterize the genetic basis of phenotypic responses to three light environments by studying individuals of known genetic relationship in a natural population of the winter annual wildflower, Collinsia verna (blue-eyed Mary). The PIs will examine the fitness consequences of light-induced phenotypic changes by studying traits known to respond to different light levels and/or to be closely related to fitness (e.g., germination date, size at overwintering, leaf size and shape, plant size and branching pattern, date of first flowering, number of flowers, number of seeds, and seed size). Human activity is causing unprecedented environmental change at all scales from local habitat fragmentation to global climate change, with far reaching consequences for earth's biodiversity. The results of this research will contribute to our understanding of many important questions about biodiversity and it s management: What are the determinants of species ranges? What constitutes a stressful environment for a species? How do individuals and species respond to novel and changing environments? When can species be reasonably expected to adapt to change, as opposed to going extinct? By assessing the adaptive nature of phenotypic responses to light, and by quantifying the potential for the further change in plastic traits, this study will make an important contribution to our understanding natural selection in heterogeneous or changing environments.