Data from: Human-facilitated metapopulation dynamics in an emerging pest species, Cimex lectularius

The number and demographic history of colonists can have dramatic consequences for the way in which genetic diversity is distributed and maintained in a metapopulation. The bed bug (Cimex lectularius) is a re-emerging pest species whose close association with humans has led to frequent local extinction and colonisation, i.e. to metapopulation dynamics. Pest control limits the lifespan of sub-populations, causing frequent local extinctions, and human-facilitated dispersal allows the colonisation of empty patches. Founder events often result in drastic reductions in diversity and an increased influence of genetic drift. Coupled with restricted migration this can lead to rapid population differentiation. We therefore predicted strong population structuring. Here, using 21 newly characterised microsatellite markers and Approximate Bayesian Computation (ABC), we investigate simplified versions of two classical models of metapopulation dynamics, in a coalescent framework, in order to estimate the number and genetic composition of founders in the common bed bug. We found very limited diversity within infestations but high degrees of structuring across the city of London, with extreme levels of genetic differentiation between infestations (FST = 0.59). ABC results suggest a common origin of all founders of a given sub-population and that the numbers of colonists were low; implying that even a single mated female is enough to found a new infestation successfully. These patterns of colonisation are close to the predictions of the propagule pool model, where all founders originate from the same parental infestation. These results show that aspects of metapopulation dynamics can be captured in simple models and provide insights that are valuable for the future targeted control of bed bug infestations.

殖民者的数量与种群历史，对集合种群（metapopulation）内遗传多样性的分布与维持模式可产生显著影响。温带臭虫（Cimex lectularius）是一类再度暴发的有害生物，其与人类的高度共生关系导致频繁的局域灭绝与定殖事件，呈现出典型的集合种群动态特征。虫害防控措施会缩短亚种群的存续时长，引发频繁的局域灭绝；而人类活动介导的扩散则使空生境斑块得以被成功定殖。奠基者事件往往会导致遗传多样性大幅降低，并增强遗传漂变的作用强度。若再结合有限的基因流，该过程可快速引发种群分化，因此我们推测温带臭虫种群存在显著的空间结构。
本研究依托21个新开发的微卫星标记（microsatellite markers）与近似贝叶斯计算（Approximate Bayesian Computation，ABC），在溯祖框架（coalescent framework）下对两种经典集合种群动态模型的简化版本展开分析，旨在估算温带臭虫的奠基者数量与遗传组成。
研究结果显示，单个侵害位点内的遗传多样性极为有限，但在伦敦全市范围内却存在高度的种群空间结构，不同侵害位点间的遗传分化程度极高（FST = 0.59）。近似贝叶斯计算结果表明，同一亚种群的所有奠基个体均具有共同的起源，且定殖者的数量极少——这意味着即便仅一只交配过的雌性臭虫，便足以成功建立新的侵害种群。
此类定殖模式与繁殖体库模型（propagule pool model）的预测高度吻合，该模型假定所有奠基个体均源自同一个亲本侵害位点。本研究结果证实，集合种群动态的部分特征可通过简单模型得以阐释，相关发现可为未来温带臭虫侵害的精准防控提供极具价值的理论参考。