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.

定植者的数量与种群历史，可对集合种群（metapopulation）内遗传多样性的分布与维持模式产生显著影响。温带臭虫（Cimex lectularius）是一类重新复苏的害虫，因其与人类的密切共生关系而频繁发生局部灭绝与再定植事件，即呈现集合种群动态特征。虫害防控措施会缩短亚种群的存续时长，引发频繁的局部灭绝事件；而人类活动介导的扩散则为空斑块的再定植提供了条件。奠基者事件往往会导致遗传多样性的急剧下降，并增强遗传漂变的作用强度。若结合有限的基因流，这一效应将加速种群的遗传分化，因此我们推测该物种具有较强的种群结构分化。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）下对两类经典集合种群动态模型的简化版本展开分析，以估算温带臭虫的奠基者数量与遗传组成。研究结果显示，单个侵染斑块内的遗传多样性极为有限，但伦敦全市范围内的种群结构分化程度极高，各侵染斑块间的遗传分化水平极端显著（FST=0.59）。近似贝叶斯计算的分析结果表明，同一亚种群的所有奠基个体均源自共同的亲本种群，且定植者的数量极少——这意味着仅需一只已交配的雌性臭虫即可成功建立新的侵染种群。这类定植模式与繁殖体库模型（propagule pool model）的预测结果高度吻合，该模型假定所有奠基个体均来自同一亲本侵染斑块。本研究结果证实，简单模型即可捕捉集合种群动态的部分核心特征，相关结论可为未来温带臭虫侵染的精准防控提供极具价值的理论依据。