Data from: History cleans up messes: the impact of time in driving divergence and introgression in a tropical suture zone

Contact zones provide an excellent arena in which to address questions about how genomic divergence evolves during lineage divergence. They allow us to both infer patterns of genomic divergence in allopatric populations isolated from introgression and to characterize patterns of introgression after lineages meet. Thusly motivated, we analyze genome-wide introgression data from four contact zones in three genera of lizards endemic to the Australian Wet Tropics. These contact zones all formed between morphologically cryptic lineage-pairs within morphologically defined species, and the lineage-pairs meeting in the contact zones diverged anywhere from 3.1 to 5.8 million years ago. By characterizing patterns of molecular divergence across an average of 11K genes and fitting geographic clines to an average of 7.5K variants, we characterize how patterns of genomic differentiation and introgression change through time. Across this range of divergences, we find that genome-wide differentiation increases but becomes no less heterogeneous. In contrast, we find that introgression heterogeneity decreases dramatically, suggesting that time helps isolated genomes ”congeal”. Thus, this work emphasizes the pivotal role that history plays in driving lineage divergence.接触带（contact zone）为探究谱系分化过程中基因组分化的演化机制提供了绝佳的研究场景。其既可以帮助我们推断未受基因渐渗（introgression）干扰的异域种群（allopatric population）的基因组分化模式，也可以刻画谱系相遇后的基因渐渗特征。基于上述研究动机，我们对澳大利亚湿热带（Australian Wet Tropics）特有蜥蜴三个属的四个接触带的全基因组基因渐渗数据展开分析。这些接触带均形成于形态学界定物种内部的形态隐存谱系对之间，且这些在接触带相遇的谱系对的分化时间介于310万至580万年之间。通过对平均11000个基因的分子分化模式进行刻画，并对平均7500个变异位点拟合地理渐变群（geographic cline）模型，我们解析了基因组分化与基因渐渗模式随时间的变化规律。在该分化时间区间内，我们发现全基因组分化水平有所上升，但其异质性并未出现下降。与之相反，基因渐渗的异质性显著降低，这表明时间可帮助隔离的基因组逐渐“固化”。因此，本研究凸显了历史因素在推动谱系分化过程中的关键作用。