Maestri Renan, Monteiro Leandro Rabello, Fornel Rodrigo, Upham Nathan S, Patterson Bruce D, de Freitas Thales Renato Ochotorena
Programa de Pós-Graduação em Ecologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 91501, Brazil.
Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, 60605.
Evolution. 2017 Mar;71(3):610-632. doi: 10.1111/evo.13155. Epub 2017 Jan 16.
Evolutionary radiations on continents are less well-understood and appreciated than those occurring on islands. The extent of ecological influence on species divergence can be evaluated to determine whether a radiation was ultimately the outcome of divergent natural selection or else arose mainly by nonecological divergence. Here, we used phylogenetic comparative methods to test distinct hypotheses corresponding to adaptive and nonadaptive evolutionary scenarios for the morphological evolution of sigmodontine rodents. Results showed that ecological variables (diet and life-mode) explain little of the shape and size variation of sigmodontine skulls and mandibles. A Brownian model with varying rates for insectivory versus all other diets was the most likely evolutionary model. The insectivorous sigmodontines have a faster rate of morphological evolution than mice feeding on other diets, possibly due to stronger selection for features that aid insectivory. We also demonstrate that rapid early-lineage diversification is not accompanied by high morphological divergence among subclades, contrasting with island results. The geographic size of continents permits spatial segregation to a greater extent than on islands, allowing for allopatric distributions and escape from interspecific competition. We suggest that continental radiations of rodents are likely to produce a pattern of high species diversification coupled with a low degree of phenotypic specialization.
与发生在岛屿上的进化辐射相比，大陆上的进化辐射得到的理解和重视较少。可以评估生态对物种分化的影响程度，以确定一次辐射最终是趋异自然选择的结果，还是主要由非生态分化产生。在这里，我们使用系统发育比较方法来检验与稻鼠型啮齿动物形态进化的适应性和非适应性进化情景相对应的不同假设。结果表明，生态变量（饮食和生活方式）对稻鼠型啮齿动物头骨和下颌骨的形状和大小变化解释甚少。一个对食虫类与所有其他饮食具有不同变化速率的布朗模型是最可能的进化模型。食虫类稻鼠型啮齿动物的形态进化速率比以其他饮食为食的小鼠更快，这可能是由于对有助于食虫的特征有更强的选择。我们还证明，早期谱系的快速分化并不伴随着亚分支之间的高度形态差异，这与岛屿上的结果形成对比。大陆的地理面积比岛屿允许更大程度的空间隔离，从而形成异域分布并避免种间竞争。我们认为，啮齿动物在大陆上的辐射很可能产生一种物种高度多样化且表型特化程度较低的模式。
