Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales 2751, Australia.
Proc Biol Sci. 2022 Mar 30;289(1971):20212582. doi: 10.1098/rspb.2021.2582.
It is hard to overemphasize the importance of endosymbionts in arthropod biology, ecology and evolution. Some endosymbionts can complement host metabolic function or provide defence against pathogens; others, such as ubiquitous and , have evolved strategies to manipulate host reproduction. A common reproductive manipulation strategy is cytoplasmic incompatibility (CI) between differently infected individuals which can result in female mortality or male development of fertilized eggs in haplodiploid hosts. Recently, an additional role of endosymbionts has been recognized in the modification of sex allocation in sexually reproducing haplodiploids. This was theoretically expected due to the maternal inheritance of endosymbionts and natural selection for them to increase infected female production, yet the underlying mechanism remained unknown. Here, we tested whether and how and causing different CI types interact to increase female production in a haplodiploid thrips species where sex allocation depends on both maternal condition and egg size provisioning. We found that augmented female production by increasing maternal fitness and egg size, thereby boosting fertilization rate and offspring fitness. , in contrast, reduced the beneficial effects of . Our results demonstrate different invasion strategies and antagonistic effects of endosymbiotic bacteria on host fitness and evolution of sex allocation.
在节肢动物生物学、生态学和进化中，内共生体的重要性怎么强调都不为过。一些内共生体能补充宿主的代谢功能或提供抵御病原体的防御；另一些内共生体，如普遍存在的 和 ，则进化出了操纵宿主繁殖的策略。一种常见的生殖操纵策略是不同感染个体之间的细胞质不相容性（CI），这可能导致雌性死亡或雄性受精卵发育在单倍二倍体宿主中。最近，内共生体在改变有性生殖单倍二倍体的性别分配方面的另一个作用得到了认可。由于内共生体的母系遗传以及自然选择有利于它们增加感染雌性的产量，因此理论上可以预期到这一点，但潜在的机制仍然未知。在这里，我们测试了 和 引起不同 CI 类型的内共生体是否以及如何相互作用，以增加一种依赖于母体状况和卵大小供应的单倍二倍体蓟马物种的雌性产量。我们发现 通过增加母体适应性和卵大小来增加雌性产量，从而提高受精率和后代适应性。相比之下， 降低了 的有益影响。我们的结果表明，内共生细菌对宿主适应性和性别分配进化具有不同的入侵策略和拮抗作用。
