Bernos Thaïs A, Avlijaš Sunčica, Hill Jaclyn, Morissette Olivier, Ricciardi Anthony, Mandrak Nicholas E, Jeffries Kenneth M
Department of Ecology and Evolutionary Biology University of Toronto Toronto Ontario Canada.
Department of Biological Sciences University of Toronto Scarborough Scarborough Ontario Canada.
Evol Appl. 2022 Dec 20;16(1):173-188. doi: 10.1111/eva.13520. eCollection 2023 Jan.
Introduced and geographically expanding populations experience similar eco-evolutionary challenges, including founder events, genetic bottlenecks, and novel environments. Theory predicts that reduced genetic diversity resulting from such phenomena limits the success of introduced populations. Using 1900 SNPs obtained from restriction-site-associated DNA sequencing, we evaluated hypotheses related to the invasion history and connectivity of an invasive population of Tench (), a Eurasian freshwater fish that has been expanding geographically in eastern North America for three decades. Consistent with the reported history of a single introduction event, our findings suggest that multiple introductions from distinct genetic sources are unlikely as Tench had a small effective population size (~114 [95% CI = 106-123] individuals), no strong population subdivision across time and space, and evidence of a recent genetic bottleneck. The large genetic neighbourhood size (220 km) and weak within-population genetic substructure suggested high connectivity across the invaded range, despite the relatively large area occupied. There was some evidence for a small decay in genetic diversity as the species expanded northward, but not southward, into new habitats. As eradicating the species within a ~112 km radius would be necessary to prevent recolonization, eradicating Tench is likely not feasible at watershed-and possibly local-scales. Management should instead focus on reducing abundance in priority conservation areas to mitigate adverse impacts. Our study indicates that introduced populations can thrive and exhibit relatively high levels of genetic diversity despite severe bottlenecks (<1.5% of the ancestral effective population size) and suggests that landscape heterogeneity and population demographics can generate variability in spatial patterns of genetic diversity within a single range expansion.
新引入且在地理上不断扩张的种群面临着相似的生态进化挑战，包括奠基者事件、遗传瓶颈和新环境。理论预测，此类现象导致的遗传多样性降低会限制引入种群的成功。我们利用从限制性内切酶相关DNA测序获得的1900个单核苷酸多态性（SNP），评估了与丁鱥入侵种群的入侵历史和连通性相关的假设。丁鱥是一种欧亚淡水鱼，在北美东部已经地理扩张了三十年。与报道的单次引入事件历史一致，我们的研究结果表明，不太可能存在来自不同遗传源的多次引入，因为丁鱥的有效种群规模较小（约114只[95%置信区间=106 - 123]），在时间和空间上没有明显的种群细分，并且有近期遗传瓶颈的证据。尽管占据的区域相对较大，但较大的遗传邻域大小（220公里）和种群内较弱的遗传亚结构表明在入侵范围内具有较高的连通性。有证据表明，随着该物种向北扩张到新栖息地，遗传多样性略有下降，但向南扩张时没有。由于要防止重新定殖需要在约112公里半径内根除该物种，因此在流域尺度甚至可能在局部尺度上根除丁鱥可能不可行。管理措施应转而侧重于在优先保护区减少其数量，以减轻不利影响。我们的研究表明，尽管存在严重的瓶颈（小于祖先有效种群大小的1.5%），引入种群仍能繁荣并表现出相对较高水平的遗传多样性，并表明景观异质性和种群统计学特征可在单一范围扩张内产生遗传多样性空间模式的变异性。
