The common bedbug Cimex lectularius is a widespread ectoparasite on humans and bats. Two genetically isolated lineages, parasitizing either human (HL) or bat (BL) hosts, have been suggested to differentiate because of their distinct ecology. The distribution range of BL is within that of HL and bedbugs live mostly on synanthropic bat hosts. This sympatric co-occurrence predicts strong reproductive isolation at the post-copulatory level. We tested the post-copulatory barrier in three BL and three HL populations in reciprocal crosses, using a common-garden blood diet that was novel to both lineages. We excluded pre-copulation isolation mechanisms and studied egg-laying rates after a single mating until the depletion of sperm, and the fitness of the resulting offspring. We found a higher sperm storage capability in BL, likely reflecting the different seasonal availability of HL and BL hosts. We also observed a notable variation in sperm function at the population level within lineages and significant differences in fecundity and offspring fitness between lineages. However, no difference in egg numbers or offspring fitness was observed between within- and between-lineage crosses. Differences in sperm storage or egg-laying rates between HL and BL that we found did not affect reproductive isolation. Neither did the population-specific variation in sperm function. Overall, our results show no post-copulatory reproductive isolation between the lineages. How genetic differentiation in sympatry is maintained in the absence of a post-copulatory barrier between BL and HL remains to be investigated.

中文翻译：

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尽管同源基因隔离，但蝙蝠和人类相关的常见臭虫（Cimex lectularius L.）之间尚未进化出交配后生殖障碍。

常见的臭虫 Cimex lectularius 是一种广泛存在于人类和蝙蝠身上的体外寄生虫。寄生于人类（HL）或蝙蝠（BL）宿主的两个基因分离谱系由于其独特的生态学而被认为是有区别的。BL 的分布范围在 HL 的范围之内，臭虫主要生活在共生蝙蝠宿主上。这种同域共现预示着交配后水平上的强烈生殖隔离。我们使用对这两个谱系来说都是新颖的普通花园血液饮食，在相互杂交中测试了三个 BL 群体和三个 HL 群体的交配后屏障。我们排除了交配前的隔离机制，并研究了单次交配后直至精子耗尽的产卵率，以及由此产生的后代的健康状况。我们发现 BL 具有更高的精子储存能力，这可能反映了 HL 和 BL 宿主的不同季节可用性。我们还观察到谱系内群体水平上精子功能的显着差异以及谱系之间繁殖力和后代适应性的显着差异。然而，在谱系内和谱系间杂交之间没有观察到卵数或后代适应性的差异。我们发现 HL 和 BL 之间精子储存或产卵率的差异不会影响生殖隔离。精子功能的人群特异性变异也没有。总的来说，我们的结果表明谱系之间不存在交配后生殖隔离。在 BL 和 HL 之间不存在交配后屏障的情况下，如何维持同源性的遗传分化仍有待研究。