DISSERTATION RESEARCH: The phylogenetic history of Plestiodon and a new empirical perspective on multi-locus molecular dating methods

研究人员早就认识到，精确的分子时钟对重要进化事件的日期具有潜在的解释能力。不幸的是，现在人们认识到，分子进化通常不是以时钟的方式进行的，更复杂的放松时钟方法的开发正在进行中。这项研究的一个主要目标将是评估新开发的松弛时钟发散测年方法的假设和行为，在20个地点的经验数据集的背景下，对蜥蜴属Plstiodon。蜥蜴是生物学研究的常见对象，生活在美国大部分地区，但人们对它们的进化史知之甚少。识别和测定过去的生物事件是进化生物学的一个基本目标。年表是分析历史生物地理学的中心，也是阐明形态结构、行为或生理进化速度的核心。此外，重要的是确定关键进化事件的日期，无论这些事件是灭绝事件、历史人类迁徙事件还是与疾病暴发相关的流行病学事件。这项考察最近发展的分子测年方法性能的研究结果将适用于整个分子发散测年领域，并将提高生物学家估计重要生物事件时间的能力。

Researchers have long recognized the potential explanatory power of precise molecular clocks for placing dates on important evolutionary events. Unfortunately, it is now recognized that molecular evolution often does not proceed in a clock-like fashion and development of more complex relaxed-clock methods is ongoing. A major goal of this study will be to evaluate the assumptions and behavior of newly developed relaxed-clock divergence dating methodologies in the context of a 20-locus empirical data set for the scincid lizard genus Plestiodon. Plestiodon lizards are a common subject of biological research and inhabit most of the United States, yet little is known about their evolutionary history. Identifying and dating biological events in the past is a fundamental goal of evolutionary biology. Chronology is central to analyses of historical biogeography, as well as to efforts to elucidate the rate at which a morphological structures, behaviors, or physiologies have evolved. It is furthermore important to place dates on critical evolutionary events, whether they be extinction events, historical human migration events, or epidemiological events associated with disease outbreak. The results of this research investigating the performance of recently developed molecular dating methodologies will be applicable to the entire field of molecular divergence dating and will improve the ability of biologists to estimate the timing of important biological events.