Dissertation Research: The Pattern and Process of Evolutionary Diversification: Lessons from an Alaskan Threespine Stickleback Radiation

冰川期后的三刺棘鱼代表了自然界生物多样性最具启发性的案例之一。这项研究揭示了冰期后棘鱼种群起源的过程，以及造成它们之间存在差异的因素。首先，将对最近建立的湖泊种群的进化轨迹进行评估，这些种群来自于一种类似于建立更广泛的区域适应性辐射的海洋形式。所讨论的问题包括湖泊分离物与海洋祖先的分化速度有多快，自然界进化轨迹的形式以及祖先变异对这些轨迹的影响。然后，在更广泛的区域适应性辐射中，基因流和自然选择对表型分化的相对重要性将通过应用传统和新颖的地理分析方法对阿拉斯加库克湾不同棘鱼湖流辐射进行评估。本研究结合强大的形态计量学、分子学和地理学方法，以数十年来积累的有关三刺鱼生态学和进化的资源为基础，对自然界的微观进化过程进行实证研究。所讨论的问题对于了解生物多样性的起源和维持至关重要，并为保护不同种群提供了标准。

Postglacial threespine stickleback fish represent one of our most enlightening cases of biological diversification in nature. This study sheds light on the process through which postglacial stickleback populations originate and the factors responsible for the differences that exist among them. First, the evolutionary trajectory of a recently established lake population, derived from an oceanic form similar to the one that founded the broader regional adaptive radiation, will be evaluated. Issues addressed include how quickly lake isolates can diverge from their oceanic ancestors, the form evolutionary trajectories take in nature and the influence ancestral variation has on those trajectories. Then, the relative importance of gene flow and natural selection on phenotypic divergence within the broader regional adaptive radiation will be evaluated by applying traditional and novel methods of geographical analysis on a diverse stickleback lake-stream radiation in Cook Inlet, Alaska. This study combines powerful morphometric, molecular and geographical methods, and builds on decades of accumulated resources related to threespine stickleback ecology and evolution, to empirically examine microevolutionary processes in nature. The issues addressed are critical for understanding the origin and maintenance of biodiversity and provide criteria for conserving divergent populations.