Data from: Genetic patterns across an invasion's history: a test of change versus stasis for the Eurasian round goby in North America

Biological invasions comprise accidental evolutionary experiments, whose genetic compositions underlie relative success, spread, and persistence in new habitats. However, little is known about whether, or how, their population genetic patterns change temporally and/or spatially across the invasion's history. Theory predicts that most would undergo founder effect, exhibit low genetic divergence across the new range, and gain variation over time via new arriving propagules. To test these predictions, we analyze population genetic diversity and divergence patterns of the Eurasian round goby Neogobius melanostomus across the two decades of its North American invasion in the Laurentian Great Lakes, comparing results from 13 nuclear DNA microsatellite loci and mitochondrial DNA cytochrome b sequences. We test whether “genetic stasis”, “genetic replacement”, and/or “genetic supplement” scenarios have occurred at the invasion's core and expansion sites, in comparison to its primary native source population in the Dnieper River, Black Sea. Results reveal pronounced genetic divergence across the exotic range, with population areas remaining genetically distinct and statistically consistent across two decades, supporting “genetic stasis” and “founder takes most”. The original genotypes continue to predominate, whose high population growth likely outpaced the relative success of later arrivals. The original invasion core has stayed the most similar to the native source. Secondary expansion sites indicate slight allelic composition convergence towards the core population over time, attributable to some early “genetic supplementation”. The geographic and temporal coverage of this investigation offers a rare opportunity to discern population dynamics over time and space in context of invasion genetic theory versus reality.

生物入侵本质上属于偶然发生的进化实验，其遗传组成是该物种在新生境中实现相对成功、完成扩散并持续存续的基础。然而学界目前对入侵历史中，种群遗传格局随时间和/或空间发生的变化规律仍知之甚少。理论预测，多数入侵物种会经历奠基者效应（founder effect），在新生分布区内表现出较低的遗传分化，并随着时间推移通过新抵达的繁殖体（propagules）获得遗传变异。为验证上述理论预测，我们针对欧亚圆虎鱼（Neogobius melanostomus）——该物种在北美劳伦斯大湖（Laurentian Great Lakes）已完成二十年入侵历程——的种群遗传多样性与分化格局展开分析，基于13个核DNA微卫星位点（nuclear DNA microsatellite loci）与线粒体DNA细胞色素b（cytochrome b）序列的测序结果进行比较。我们以其原生境的主要来源种群——黑海（Black Sea）流域第聂伯河（Dnieper River）种群作为参照，检验入侵核心区与扩张区域是否发生了“遗传稳态（genetic stasis）”、“遗传替换（genetic replacement）”或“遗传补充（genetic supplement）”情景。研究结果显示，该外来物种的分布区内存在显著的遗传分化，且各采样区域的种群遗传特征在二十年的时间跨度内始终保持显著差异且统计一致性稳定，这一结果支持“遗传稳态”与“奠基者主导（founder takes most）”假说。原始基因型仍占据种群主导地位，其快速的种群增长可能远超后续抵达繁殖体的定殖成功率。最初形成的入侵核心区与原生来源种群的遗传相似性最高。次级扩张区域的等位基因组成（allelic composition）随时间推移呈现出向核心种群轻微趋同的趋势，这一现象可归因于早期发生的少量“遗传补充”事件。本研究在时间与空间维度上的采样覆盖度，为在入侵遗传理论的框架下解析种群动态的真实规律提供了难得的研究契机。