Dissertation Research: Mitochondrial Phylogeny of New WorldMonkeys

新世界猴物种之间的进化关系知之甚少。 形态学特征与核DNA序列的关系已经产生了几种不同的假说。 新大陆猴的三个主要类群--绢毛猴（绢毛猴和绒猴）、猴（沙猴和乌卡里斯猴）和猴（蜘蛛猴、毛猴和毛蜘蛛猴），在所有这些研究中都得到了很好的支持。 然而，大多数其他关系显示出微弱的支持，并且在不同的研究中存在差异，这表明在某些情况下发生了一系列快速的物种形成事件（或进化辐射）。 位于线粒体（核细胞器）中的基因平均进化速度比核基因更快，在快速进化辐射过程中积累更多突变的机会也更高。 因此，将现有数据集（形态学和核）与线粒体数据相结合的潜在优势。 这个项目的主要目的是澄清新世界猴属之间的关系。 为此，研究人员打算：1）对新世界猴所有属的线粒体基因（12 S核糖体基因）进行测序，以研究它们的进化关系; 2）将12 S序列与已发表的核、形态和初步线粒体数据相结合，以生成一个“全证据”进化树; 3）评价不同的方法来分配不同的权重到单个字符。 研究人员将假设，一种方法，产生的物种calithrichids，pithecines，atelines，以这种方式分类，比一种方法，没有表现得更好，因为这些都是很好的确证关系。 该项目的意义在于：1）它进一步了解了新世界猴之间鲜为人知的进化关系; 2）它提供了一个系统发育框架来测试这一群体的进化假设; 3）它提供了不同加权方法的性能测试。

Evolutionary relationships among species of New World monkeys are poorly known. Several different hypotheses of relationships have been generated with morphological characters and nuclear DNA sequences. Three major groups o f New World monkeys-callithrichids (tamarins and marmosets), pithecines (sakis and uakaris), and atelines (spider, woolly, and woolly-spider monkeys), are well supported in all of these studies. However, most of all other relationships show weak support and differ across studies, suggesting that a fast sequence of speciation events (or evolutionary radiation) occurred in some cases. Genes located in the mitochondria (extranuclear cellular organelles) have a higher rate of evolution on average than nuclear genes and chances are higher that more mutations accumulate during rapid evolutionary radiations. Hence the potential advantage of combining the existing data sets (morphological and nuclear) with mitochondrial data. The major aim of this project is to clarify the relationships among New World monkey genera. For this purpose, the researchers intend to: 1) sequence a mitochondrial gene, the 12S ribosomal gene in all genera of New World monkeys, to conduct a study of their evolutionary relationships; 2) combine the 12S sequences with published nuclear, morphological and preliminary mitochondrial data to generate a `total evidence` evolutionary tree; 3) evaluate different methods to assign differential weights to individual characters. The researchers will assume that a method that yields the species of callithrichids, pithecines, and atelines, assorted in that way, performs better than a method that does not, because these are well corroborated relationships. The project is significance because: 1) it furthers knowledge about the poorly known evolutionary relationships among New World monkeys; 2) it provides a phylogenetic framework to test hypotheses of evolution in this group; 3) it provides a test of the performance of different weighting methods.