Abstract：
Recent genomic analyses have highlighted the prevalence of speciation with gene flow in many taxa and have underscored the importance of accounting for these reticulate evolutionary processes when constructing species trees and generating parameter estimates. This is especially important for deepening our understanding of speciation in the sea where fast moving ocean currents, expanses of deep water, and periodic episodes of sea level rise and fall act as soft and temporary allopatric barriers that facilitate both divergence and secondary contact. Under these conditions, gene flow is not expected to cease completely while contemporary distributions are expected to differ from historical ones. Here we conduct range-wide sampling for Pederson\'s cleaner shrimp (Ancylomenes pedersoni), a species complex from the Greater Caribbean that contains three clearly delimited mitochondrial lineages with both allopatric and sympatric distributions. Using mtDNA barcodes and a genomic ddRADseq approach, we combine classic phylogenetic analyses with extensive topology testing and demographic modeling (10 site frequency replicates x 45 evolutionary models x 50 model simulations/replicate = 22,500 simulations) to test species boundaries and reconstruct the evolutionary history of what was expected to be a simple case study. Instead, our results indicate a history of allopatric divergence, secondary contact, introgression, and endemic hybrid speciation that we hypothesize was driven by the final closure of the Isthmus of Panama and the strengthening of the Gulf Stream Current ~3.5 million years ago. The history of this species complex recovered by model-based methods that allow reticulation differs from that recovered by standard phylogenetic analyses and is unexpected given contemporary distributions. The geologically and biologically meaningful insights gained by our model selection analyses illuminate what is likely a novel pathway of species formation not previously documented that resulted from one of the most biogeographically significant events in Earth\'s history.
摘要：
最近的基因组分析强调了许多分类单元中具有基因流的物种形成的普遍性，并强调了在构建物种树和生成参数估计时考虑这些网状进化过程的重要性。这对于加深我们对海中物种形成的理解尤其重要，广阔的深水，海平面上升和下降的周期性事件充当软的和临时的同种屏障，促进了发散和二次接触。在这些条件下,基因流动预计不会完全停止，而当代分布预计将不同于历史分布。在这里，我们对佩德森的清洁虾（Ancylomenespedersoni）进行了范围采样，大加勒比海地区的一种物种复合体，包含三个清晰界定的线粒体谱系，具有异域和同胞分布。使用mtDNA条形码和基因组ddRADseq方法，我们将经典的系统发育分析与广泛的拓扑测试和人口统计学建模（10个站点频率重复x45个进化模型x50个模型模拟/重复=22,500个模拟）相结合，以测试物种边界并重建预期是一个简单案例研究的进化史。相反，我们的结果表明有异向分歧的历史，二次接触,渗入,我们假设的地方性混合物种形成是由巴拿马地峡的最终关闭和约350万年前墨西哥湾流的加强所驱动的。通过基于模型的方法恢复的该物种复合体的历史与通过标准系统发育分析恢复的历史不同，并且鉴于当代分布，这是出乎意料的。通过我们的模型选择分析获得的地质和生物学上有意义的见解阐明了可能是一种新的物种形成途径，以前没有记录过，这是地球历史上最具生物地理意义的事件之一。
