Laboratório de Genética e Evolução Molecular de Aves, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, 05508-090 São Paulo, SP, Brazil.
Mol Phylogenet Evol. 2012 Dec;65(3):892-902. doi: 10.1016/j.ympev.2012.08.010. Epub 2012 Aug 24.
In this study we analyzed the phylogeographic pattern and historical demography of an endemic Atlantic forest (AF) bird, Basileuterus leucoblepharus, and test the influence of the last glacial maximum (LGM) on its population effective size using coalescent simulations. We address two main questions: (i) Does B. leucoblepharus present population genetic structure congruent with the patterns observed for other AF organisms? (ii) How did the LGM affect the effective population size of B. leucoblepharus? We sequenced 914 bp of the mitochondrial gene cytochrome b and 512 bp of the nuclear intron 5 of beta-fibrinogen of 62 individuals from 15 localities along the AF. Both molecular markers revealed no genetic structure in B. leucoblepharus. Neutrality tests based on both loci showed significant demographic expansion. The extended Bayesian skyline plot showed that the species seems to have experienced demographic expansion starting around 300,000 years ago, during the late Pleistocene. This date does not coincide with the LGM and the dynamics of population size showed stability during the LGM. To further test the effect of the LGM on this species, we simulated seven demographic scenarios to explore whether populations suffered specific bottlenecks. The scenarios most congruent with our data were population stability during the LGM with bottlenecks older than this period. This is the first example of an AF organism that does not show phylogeographic breaks caused by vicariant events associated to climate change and geotectonic activities in the Quaternary. Differential ecological, environmental tolerances and habitat requirements are possibly influencing the different evolutionary histories of these organisms. Our results show that the history of organism diversification in this megadiverse Neotropical forest is complex.
在这项研究中，我们分析了一种特有大西洋森林（AF）鸟类——白耳鹎的系统地理格局和历史种群动态，并利用合并模拟检验末次冰盛期（LGM）对其有效种群大小的影响。我们主要探讨了两个问题：（i）白耳鹎是否表现出与其他 AF 生物一致的种群遗传结构？（ii）LGM 如何影响白耳鹎的有效种群大小？我们对来自 AF 15 个地点的 62 只个体的线粒体基因细胞色素 b 进行了 914bp 测序和核内β-纤维蛋白原内含子 5 进行了 512bp 测序。两个分子标记均未显示白耳鹎存在遗传结构。基于两个基因座的中性检验均显示出显著的种群扩张。扩展的贝叶斯天空线图表明，该物种似乎在约 30 万年前的更新世晚期经历了种群扩张。这个日期与 LGM 并不吻合，种群大小的动态在 LGM 期间表现出稳定。为了进一步检验 LGM 对该物种的影响，我们模拟了七个种群动态场景，以探索其种群是否经历了特定瓶颈。与我们的数据最吻合的场景是 LGM 期间的种群稳定，而瓶颈发生在这一时期之前。这是第一个没有显示出由于第四纪气候变化和地球构造活动导致的地理隔离断点的 AF 生物的例子。不同的生态、环境耐受性和栖息地需求可能影响这些生物的不同进化历史。我们的研究结果表明，在这个生物多样性丰富的新热带森林中，生物多样化的历史是复杂的。
