Morphological and Phylogenetic Diversification in the Tamarins

拟议的研究的主要目标是发展的形态差异的进化起源的绒猴物种（属Saguinus）之间的理解。 绢毛猴是一种高度多样化的新世界猴，栖息在亚马逊河流域和南美洲北海岸到巴拿马。 它们显示出各种各样的颅骨形态。 利用先前收集的关于头骨形状遗传模式和物种间系统发育关系的信息，研究人员将测试一系列关于该组形态差异进化起源的假设。 这些研究将作为分析灵长类辐射形态多样性的模型。 首先，他们将检验颅骨变异性是由随机进化过程引起的假设，如遗传漂变或随机变化的自然选择。 如果这一假设不被否定，那么观察到的多样性可能不是由于对特定环境的特殊适应而产生的。 接下来，他们将使用一个清晰的系统发育树来创建一系列姐妹群体之间的遗传独立对比。 他们将使用两组判别函数描述这些对比中的每一个，该判别函数用种内遗传协方差矩阵的估计进行标准化。 这些判别函数中的每一个都代表了自然选择中的差异模式，这些差异模式是产生所观察到的绢毛猴相关群体之间的形态差异所必需的。 将使用功能形态学的原则解释结果。 具体的先验假设，如选择的整体大小作为进化形态分歧的来源，也将进行测试。

The major objective of the proposed research is to develop an understanding of the evolutionary origins of morphological differences among tamarin species (genus Saguinus). Tamarins are a highly diverse group of New World Monkeys inhabiting Amazonia and the north coast of South America into Panama. They display a wide range of cranial morphologies. Using previously gathered information on patterns of inheritance of skull form and the phylogenetic relationships among the species, the researchers will test a series of hypotheses concerning the evolutionary origin of morphological differences in this group. The studies will serve as a model for analyzing morphological diversity in primate radiations. First, they will test the hypothesis that cranial variability arose by random evolutionary processes, such as genetic drift or randomly varying natural selection. If this hypothesis is not rejected, it is possible that the diversity observed did not arise by special adaptation to specific environments. Next they will use a well-resolved phylogenetic tree to create a series of phylogenetically-independent contrasts among sister groups. They will describe each of these contrasts using a two-group discriminant function standardized with an estimate of the within-species genetic covariance matrix. Each of these discriminant functions represents the pattern of differences in natural selection required to produce the observed morphological differences between related groups of tamarins. The results will be interpreted using the principles of functional morphology. Specific a priori hypotheses, such as selection on overall size as a source of evolutionary morphological divergence, will also be tested.