Marroig Gabriel, Cropp Susan, Cheverud James M
Departamento de Biologia Celular e Genética, Instituto de Biologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil 20550-013.
Am J Phys Anthropol. 2004 Jan;123(1):11-22. doi: 10.1002/ajpa.10146.
Interspecific differentiation and geographic variation patterns in 39 skull traits of eastern Brazilian marmosets are analyzed. Eastern Callithrix taxa are distinct morphologically, and no evidence of intergradation among taxa is observed. Instead, there are sharp, stepped morphological boundaries among taxa, consistent with species-level distinction. The morphological similarity cluster diagram obtained from Mahalanobis distances is different from available molecular trees, and the general picture emerging is that the eastern Callithrix taxa should be considered as good species arising recently in South American history. In particular, C. kuhlii is morphologically distinct from other marmoset taxa, including C. geoffroyi and C. penicillata, which were previously hypothesized to be the parental populations that formed C. kuhlii by hybridization. Furthermore, C. kuhlii populations from southeastern Bahia do not overlap morphologically with any C. penicillata population, including the upper São Francisco River populations that display skin colors and pelage patterns to some extent similar to true Kuhli's marmosets. There is a negative, though insignificant, correlation between the morphological distance matrix and a Mahalanobis distance matrix estimated from nine climatic variables, a pattern opposite to that expected under a parapatric speciation model. This result, together with the lack of clinal variation in skull traits, suggests that an allopatric model of speciation might best explain eastern marmoset diversification.
对巴西东部狨猴39个颅骨特征的种间分化和地理变异模式进行了分析。东部的绢毛猴分类群在形态上明显不同，未观察到分类群之间渐变的证据。相反，分类群之间存在明显的、阶梯状的形态界限，这与物种水平的区分相一致。从马氏距离获得的形态相似性聚类图与现有的分子树不同，总体情况是东部的绢毛猴分类群应被视为南美洲历史上近期出现的良好物种。特别是，库氏绢毛猴在形态上与其他狨猴分类群不同，包括杰氏绢毛猴和髭狨，此前曾假设它们是通过杂交形成库氏绢毛猴的亲本种群。此外，来自巴伊亚州东南部的库氏绢毛猴种群在形态上与任何髭狨种群都不重叠，包括圣弗朗西斯科河上游的种群，这些种群在一定程度上显示出与真正的库氏狨猴相似的肤色和皮毛图案。形态距离矩阵与根据九个气候变量估计的马氏距离矩阵之间存在负相关，尽管不显著，这一模式与在邻域物种形成模型下预期的模式相反。这一结果，连同颅骨特征缺乏渐变变异，表明异域物种形成模型可能最能解释东部狨猴的多样化。
