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.

奠基者的数量及种群人口历史，对集合种群（metapopulation）内遗传多样性的分布与维持模式具有显著影响。温带臭虫（Cimex lectularius）是一类重新出现的害虫，因其与人类的密切关联，频繁发生局部灭绝与定殖事件，即呈现集合种群动态特征。害虫防治措施会缩短亚种群的存续时长，引发频繁的局部灭绝；而人类活动介导的扩散则为空斑块的定殖提供了条件。奠基者事件通常会导致遗传多样性的剧烈降低，并增强遗传漂变的作用。结合有限的迁移事件，这可能会快速推动种群分化，因此我们推测其种群结构具有高度分化性。
本研究依托21个新鉴定的微卫星标记（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，旨在估算普通臭虫的奠基者数量与遗传组成。
研究结果显示，单个侵染种群内的遗传多样性极为有限，但在伦敦全市范围内却呈现出高度的种群结构，不同侵染种群间的遗传分化程度极强（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起源，且奠基者数量较少，这意味着即便仅单只已交配的雌虫即可成功建立新的侵染种群。
此类定殖模式与繁殖体库模型（propagule pool model）的预测高度吻合——该模型中所有奠基个体均来自同一亲本侵染种群。本研究证实，集合种群动态的部分特征可通过简单模型加以阐释，相关结论可为未来臭虫侵染种群的针对性防治提供极具价值的理论依据。