Data from: Genomic tests of the species-pump hypothesis: recent island connectivity cycles drive population divergence but not speciation in Caribbean crickets across the Virgin Islands

Harnessing the power of genomic scans, we test the debated ‘species pump’ hypothesis that implicates repeated cycles of island connectivity and isolation as drivers of divergence. This question has gone understudied given the limited resolution of past molecular markers for studying such dynamic phenomena. With an average of 32,000 SNPs from the genome of 136 individuals from ten populations of a Caribbean flightless ground cricket species (Amphiacusta sanctaecrucis) and a complementary set of statistical approaches, we infer a stepping-stone colonization model and high levels of genetic differentiation across the Virgin Islands, which have been periodically inter-connected until 8 ka. Estimates of divergence times from models based on the site frequency spectrum coincide with a period of repeated connection and fragmentation of the islands at 75-130 ka. These results are consistent with a role of island connectivity cycles in promoting genomic divergence and indicate that the genetic distinctiveness of island populations has persisted despite subsequent and extended interisland connections identified from bathymetric data. We discuss these findings in the broader context of Caribbean biogeography, and more specifically why high levels of genomic divergence across the Virgin Islands associated with repeated connectivity cycles do not actually translate into species diversification.本研究借助基因组扫描技术，对备受争议的‘物种泵（species pump）’假说展开检验——该假说提出岛屿连通与隔离的反复循环是物种分化的驱动因素。由于过往用于研究此类动态过程的分子标记分辨率有限，该议题长期未得到充分探讨。本研究针对10个种群的136只加勒比无翅地蟋蟀（Amphiacusta sanctaecrucis）个体的基因组进行测序，平均获得32000个单核苷酸多态性（Single Nucleotide Polymorphism, SNPs）位点，并结合一系列互补的统计学方法，推断出踏迁定殖模型（stepping-stone colonization model），同时发现维尔京群岛间存在高水平的遗传分化——该群岛在距今8000年前仍处于周期性连通状态。基于位点频率谱（site frequency spectrum, SFS）的模型所估算的分化时间，与群岛在7.5万至13万年前反复连通与碎片化的时期相吻合。上述结果支持岛屿连通循环可促进基因组分化的观点，同时表明：尽管水深测量数据显示后续存在更持久的岛间连通事件，群岛种群的遗传特异性仍得以保留。本研究将这些发现置于更广阔的加勒比生物地理学背景下展开讨论，并重点探讨了：与反复连通循环相关的维尔京群岛高水平基因组分化，为何并未实际推动物种多样化进程。