Data from: Host association drives significant genetic divergence in the bed bug, Cimex lectularius

Genetic differentiation may exist among sympatric populations of a species due to long-term associations with alternate hosts, termed “host-associated differentiation”. While it is often documented in phytophagus insects there is a paucity of empirical studies on this process in parasites. The bed bug, Cimex lectularius, represents a potential model organism for elucidating the processes involved in host-associated differentiation in parasites. In conjunction with the expansion of modern humans from Africa into Eurasia, it has been speculated that bed bugs extended their host range from bats to humans in their shared cave domiciles throughout Eurasia. C. lectularius that associate with humans have a cosmopolitan distribution, whereas those associated with bats co-occur sympatrically with human-associated bugs across Europe. We assessed genetic structure and gene flow within and among populations collected on each host using three classes of markers: mtDNA, microsatellite loci, and knock-down-resistance gene variants. Both nuclear and mitochondrial data support a lack of significant contemporary gene flow between host-specific populations. Within locations human-associated bed bug populations’ exhibit limited diversity and elevated levels of inbreeding, likely due to human-mediated movement, limited additional introduction events per infestation, and pest control. In contrast, populations within bat roosts, located in human associated properties, exhibit higher diversity and lower levels of relatedness, suggesting populations are stable with temporal fluctuations due to host dispersal and bug mortality. In concert with previously published morphological and behavioral results, the genetic data presented here suggests C. lectularius is currently undergoing lineage divergence through host-association.由于物种的同域种群（sympatric populations）与替代宿主长期形成关联，可能会产生遗传分化，该过程被称为“宿主关联分化（host-associated differentiation）”。尽管该现象在植食性昆虫（phytophagus insects）中已有诸多记载，但针对寄生虫类群的此类过程的实证研究仍较为匮乏。温带臭虫（Cimex lectularius）是研究寄生虫类群宿主关联分化过程的潜在模式生物。结合现代人类从非洲向欧亚大陆的扩张事件，有推测认为，臭虫在欧亚大陆共享的洞穴居所中，将宿主范围从蝙蝠拓展至人类。与人类关联的温带臭虫种群呈世界性分布，而与蝙蝠关联的种群则在欧洲范围内与人类关联的臭虫同域共存。本研究采用三类分子标记：线粒体DNA（mtDNA）、微卫星位点（microsatellite loci）以及击倒抗性基因变异体（knock-down-resistance gene variants），对不同宿主来源种群内部及种群间的遗传结构与基因流进行了评估。核基因组与线粒体基因组的数据均表明，宿主特化种群间不存在显著的当代基因流。在同一采样点内，与人类关联的臭虫种群表现出较低的遗传多样性与较高的近交水平，这可能源于人类活动介导的种群扩散、单次侵染事件中有限的额外迁入以及害虫防治措施的影响。与之相反，栖息于人类关联场所的蝙蝠栖息处内的臭虫种群则表现出更高的遗传多样性与更低的亲缘关系水平，表明该类种群整体较为稳定，其种群数量的时间波动源于宿主扩散与臭虫自身的死亡率。结合已发表的形态学与行为学研究结果，本研究提供的遗传数据表明，温带臭虫目前正通过宿主关联过程发生谱系分化。