A Molecular Phylogenetic Perspective on Salamander Evolution

这项研究的目的是揭示 通过研究不同蝾螈群体之间的关系， 储存在遗传物质（DNA）中的信息。 分别遗传的核DNA中所含的信息， 线粒体DNA被用来提供两个独立的推论， 不同群体的进化关系 火蜥蜴 进化关系和历史 一组生物的多样化是必不可少的 了解群体的多样性，作为一个 自然资源和保护的需要。 以下九个主要群体 蝾螈是目前公认的分类科 （Ambystomatidae，Amphiumidae，Cryptobranchidae，Dicamptodontidae， 小鲵科、大齿鲵科、变形鲵科、蝾螈科和 Sirenidae）;该项目的早期结果表明， 目前，双齿鲨科被错误地分为两类 非常不同的进化谱系。 进化 蝾螈家族之间的关系 每个家族中主要世系的关系 是这项工作的重点。 实验过程包括从DNA中纯化DNA， 标本，分离可比较的（“同源”）DNA片段， 获得这些DNA片段的核苷酸序列，并使用 判别备择假设统计检验 蝾螈的进化 物种之间的关系模式 然后用来研究生物体 在每个群体中观察到的多样性都出现了， 发展模式。 进化关系 蝾螈科用于研究幼虫的进化 繁殖，这在蝾螈身上发生过多次。 Plethodontidae内部的进化关系， 蝾螈科致力于研究 在这些家庭中观察到的喂养机制。 各级 这一分析有助于修订分类学分类 火蜥蜴 这项工作还揭示了原子核的进化特性 和线粒体DNA序列。 特别注意 用于评估分子进化模式是否 满足用于获得的分析方法的假设 DNA序列比较的进化信息。 这 结果提供了关于最佳分析的一般信息 使用的方法和进化分歧时间的大小 这些分子比较将提供信息。 这 有助于使用分子序列比较， 对其他生物群体进行类似的研究。

The purpose of this research is to reveal the evolutionary relationships among the different groups of salamanders by studying the information stored in their genetic material (DNA). Information contained in the separately inherited nuclear DNA and mitochondrial DNA is used to provide two independent inferences of the evolutionary relationships of the different groups of salamander. The evolutionary relationships and historical diversification of a group of organisms constitute essential knowledge for understanding the group's diversity, value as a natural resource and need for conservation. Nine major groups of salamanders are currently recognized as taxonomic families (Ambystomatidae, Amphiumidae, Cryptobranchidae, Dicamptodontidae, Hynobiidae, Plethodontidae, Proteidae, Salamandridae and Sirenidae); earlier results of this project suggest that the Dicamptodontidae as currently recognized incorrectly groups two very different evolutionary lineages. The evolutionary relationships of the salamander families to each other and the relationships of the major lineages contained within each family constitute the focus of this work. The experimental procedure consists of purifying DNA from specimens, isolating comparable ("homologous") segments of DNA, obtaining the nucleotide sequence of those DNA segments, and using statistical tests to discriminate alternative hypothesis of salamander evolution. The patterns of relationship among species are then used to investigate the processes by which the organismal diversity observed in each group arose, giving special attention to developmental patterns. Evolutionary relationships among the salamander families are used to investigate the evolution of larval reproduction, which has occurred multiple times in salamanders. Evolutionary relationships within the Plethodontidae and Salamandridae address the evolution of the diverse, specialized feeding mechanisms that are observed in these families. All levels of this analysis contribute to a revised taxonomic classification of the salamanders. This work also reveals the evolutionary properties of the nuclear and mitochondrial DNA sequences studied. Particular attention is given to evaluating whether the molecular evolutionary pattern meets the assumptions of the analytical methods used to obtain evolutionary information from DNA sequence comparisons. This result provides general information regarding the best analytical methods to use and the magnitude of evolutionary divergence times over which these molecular comparisons will be informative. This facilitates the use of molecular sequence comparisons for conducting similar studies on other groups of organisms.