Departamento de Ecologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91501-970, Brazil.
Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, 60605.
Evolution. 2022 Aug;76(8):1790-1805. doi: 10.1111/evo.14561. Epub 2022 Jul 19.
Investigations of phenotypic disparity across geography often ignore macroevolutionary processes. As a corollary, the random null expectations to which disparity is compared and interpreted may be unrealistic. We tackle this issue by representing, in geographical space, distinct processes of phenotypic evolution underlying ecological disparity. Under divergent natural selection, assemblages in a given region should have empirical disparity higher than expected under an evolutionarily oriented null model, whereas the opposite may indicate constraints on phenotypic evolution. We gathered phylogenies, biogeographic distributions, and data on the skull morphology of sigmodontine rodents to discover which regions of the Neotropics were more influenced by divergent, neutral, or constrained phenotypic evolution. We found that regions with higher disparity than expected by the evolutionary-oriented null model, in terms of both size and shape, were concentrated in the Atlantic Forest, suggesting a larger role for divergent natural selection there. Phenotypic disparity in the rest of South America, mainly the Amazon basin, northeastern Brazil, and Southern Andes, was constrained-lower than predicted by the evolutionary model. We also demonstrated equivalence between the disparity produced by randomization-based null models and constrained-evolution null models. Therefore, including evolutionary simulations into the null modeling framework used in ecophylogenetics can strengthen inferences on the processes underlying phenotypic evolution.
对地理分布上表型差异的研究往往忽略了宏观进化过程。因此，对差异进行比较和解释的随机零假设可能是不现实的。为了解决这个问题，我们通过在地理空间中表示生态差异背后的不同表型进化过程来处理这个问题。在发散性自然选择下，给定区域的集合应该具有比基于进化的零模型所预期的更高的经验性差异，而相反的情况则可能表明对表型进化的限制。我们收集了系统发育、生物地理分布以及关于食虫目啮齿动物头骨形态的数据，以发现哪些新热带地区受到发散、中性或受限制的表型进化的影响更大。我们发现，在大小和形状方面，与基于进化的零模型所预期的差异更大的地区集中在大西洋森林，这表明那里的发散性自然选择的作用更大。南美洲其他地区（主要是亚马逊盆地、巴西东北部和安第斯山脉南部）的表型差异受到限制——低于进化模型的预测。我们还证明了基于随机化的零模型和受限制的进化零模型产生的差异之间的等效性。因此，在生态系统发生学中使用的零模型框架中纳入进化模拟可以加强对表型进化背后过程的推断。
