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

[701148]雅若什大多数生物生活在多变的环境中。例如，几乎所有的植物在其一生中都会经历频繁的温度、光照、湿度和养分的时间波动。直到最近，生物学家才开始探讨这种环境异质性在自然选择方面的重要性。一个普遍的期望是，环境异质性将有利于植物的表型可塑性。适应性可塑性植物表达与其发生的环境条件相适应的表型。例如，在阴凉处生长的植物可能会长出又大又薄的叶子，以有效地吸收有限的光线，而在阳光充足的地方生长的同一株植物可能会长出更小、更厚的叶子，以尽量减少水分流失。与交替表型相比，每一个叶片表型允许植物更适合，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，但自然种群中表型变异的生态意义和适应性相关性却很少得到研究。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。pi将通过研究已知的响应不同光照水平和/或与适应性密切相关的性状（例如，发芽日期、越冬时的大小、叶片大小和形状、植物大小和分枝模式、首次开花日期、花的数量、种子的数量和种子的大小）来检查光诱导表型变化的适应性后果。人类活动正在造成前所未有的各种规模的环境变化，从当地栖息地破碎化到全球气候变化，对地球的生物多样性产生了深远的影响。这项研究的结果将有助于我们对生物多样性及其管理的许多重要问题的理解：物种范围的决定因素是什么？什么构成了一个物种的压力环境？个体和物种如何应对新的和不断变化的环境？什么时候物种才会适应变化，而不是走向灭绝？通过评估表型对光响应的适应性，并通过量化可塑性性状进一步变化的潜力，本研究将为我们理解异质或变化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.