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 alternative hosts (i.e., host-associated differentiation). While host-associated differentiation has been documented in several phytophagus insects, there are far fewer cases known in animal parasites. The bed bug, Cimex lectularius, a wingless insect, represents a potential model organism for elucidating the processes involved in host-associated differentiation in animal parasites with relatively limited mobility. 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 occur across Europe, often in human-built structures. We assessed genetic structure and gene flow within and among populations collected in association with each host using 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 genetic diversity and elevated levels of inbreeding, likely due to human-mediated movement, infrequent additional introduction events per infestation, and pest control. In contrast, populations within bat roosts exhibit higher genetic 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 evidence of morphological and behavioral differentiation, the genetic data presented here suggest C. lectularius is currently undergoing lineage divergence through host-association.

同一物种的同域种群间，若长期与不同宿主建立关联，可能存在遗传分化，即宿主关联分化（host-associated differentiation）。尽管已有多种植食性昆虫（phytophagus insects）被报道存在宿主关联分化现象，但动物寄生虫中的相关案例则相对稀少。温带臭虫（Cimex lectularius）作为一种无翅昆虫，是研究移动能力相对有限的动物寄生虫宿主关联分化过程的潜在模式生物。伴随现代人从非洲向欧亚大陆扩张，有假说提出，臭虫可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。与人建立关联的温带臭虫种群呈广布分布，而与蝙蝠相关的温带臭虫种群则分布于欧洲多地，且常出现在人工建造的建筑内。本研究借助线粒体DNA（mtDNA）、微卫星位点（microsatellite loci）以及击倒抗性基因（knock-down-resistance gene）变异，对不同宿主关联种群内部及种群间的遗传结构与基因流展开了评估。核基因组与线粒体基因组数据均证实，宿主特异性种群间不存在显著的当代基因流。在同一采样地点内，与人关联的温带臭虫种群遗传多样性有限且近交水平较高，这可能源于人类介导的种群扩散、单次侵染事件中额外引入事件较少，以及害虫防治措施的影响。与之形成对比的是，蝙蝠栖息环境中的温带臭虫种群遗传多样性更高，亲缘关系水平更低，表明这类种群较为稳定，其种群的时间波动由宿主扩散与臭虫死亡率共同驱动。结合此前已发表的形态与行为分化相关研究证据，本研究呈现的遗传数据表明，温带臭虫目前正通过宿主关联过程发生谱系分化（lineage divergence）。